* [PATCH v11 00/26] Speculative page faults
@ 2019-01-11 15:43 Vinayak Menon
2019-01-14 13:19 ` Vinayak Menon
0 siblings, 1 reply; 46+ messages in thread
From: Vinayak Menon @ 2019-01-11 15:43 UTC (permalink / raw)
To: ldufour; +Cc: Linux-MM, charante
Hi Laurent,
We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
Steps:
1) Run the program
2) The 2 threads will try lock/unlock and prints messages, and main thread does fork. In around 1 minute time, lock/unlock threads will hang on pthread_mutex_lock.
Initially the issue was reported when ptrace was tried on apps. Later it was discovered that the write protect done by fork is causing the issue and the below test code was created.
Observations:
1) We have tried disabling SPF and the issue disappears.
2) Adding this piece of code in __handle_speculative_fault also fixes the problem.
if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
return VM_FAULT_RETRY;
3) As an experiment we tried encapsulating handle_speculative_fault with down_read(mmap_sem) and that too fixes the problem.
4) It is observed that while in wp_page_copy, the contents of the old_page changes which should not ideally happen as the pte is !pte_write.
5) To prove that it is a race, we tried affining the threads to single core, and the issue disappears.
Let us know if you want us to try out any experiments.
Thanks,
Vinayak
/**test.c***/
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#define UNUSED(expr) do { (void)(expr); } while(0)
#define print printf
pthread_mutex_t m;
pthread_cond_t c;
static void* cond_do(void* arg)
{
UNUSED(arg);
do {
print("%s:%d state=%u addr: %lx\n", __func__, __LINE__, *(uint32_t*)(&m), (unsigned long)&m);
pthread_mutex_lock(&m);
print("%s:%d state=%u addr: %lx\n", __func__, __LINE__, *(uint32_t*)(&m), (unsigned long)&m);
pthread_mutex_unlock(&m);
print("%s:%d state=%u addr: %lx\n", __func__, __LINE__, *(uint32_t*)(&m), (unsigned long)&m);
} while (true);
return NULL;
}
static void* sig_do(void* arg)
{
UNUSED(arg);
do {
print("%s:%d state=%u addr: %lx\n", __func__, __LINE__, *(uint32_t*)(&m), (unsigned long)&m);
pthread_mutex_lock(&m);
print("%s:%d state=%u addr: %lx\n", __func__, __LINE__, *(uint32_t*)(&m), (unsigned long)&m);
pthread_mutex_unlock(&m);
print("%s:%d state=%u addr: %lx\n", __func__, __LINE__, *(uint32_t*)(&m), (unsigned long)&m);
} while (true);
return NULL;
}
int main()
{
pthread_t sig;
pthread_t cond;
pthread_mutex_init(&m, NULL);
pthread_create(&cond, NULL, cond_do, NULL);
pthread_create(&sig, NULL, sig_do, NULL);
while(1) {
if (!fork()) {
usleep(500);
abort();
}
usleep(550);
}
pthread_join(sig, NULL);
pthread_join(cond, NULL);
return 0;
}
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-11 15:43 [PATCH v11 00/26] Speculative page faults Vinayak Menon
@ 2019-01-14 13:19 ` Vinayak Menon
2019-01-15 8:24 ` Laurent Dufour
0 siblings, 1 reply; 46+ messages in thread
From: Vinayak Menon @ 2019-01-14 13:19 UTC (permalink / raw)
To: ldufour; +Cc: Linux-MM, charante
On 1/11/2019 9:13 PM, Vinayak Menon wrote:
> Hi Laurent,
>
> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
With the patch below, we don't hit the issue.
From: Vinayak Menon <vinmenon@codeaurora.org>
Date: Mon, 14 Jan 2019 16:06:34 +0530
Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
It is observed that the following scenario results in
threads A and B of process 1 blocking on pthread_mutex_lock
forever after few iterations.
CPU 1 CPU 2 CPU 3
Process 1, Process 1, Process 1,
Thread A Thread B Thread C
while (1) { while (1) { while(1) {
pthread_mutex_lock(l) pthread_mutex_lock(l) fork
pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
} }
When from thread C, copy_one_pte write-protects the parent pte
(of lock l), stale tlb entries can exist with write permissions
on one of the CPUs at least. This can create a problem if one
of the threads A or B hits the write fault. Though dup_mmap calls
flush_tlb_mm after copy_page_range, since speculative page fault
does not take mmap_sem it can proceed further fixing a fault soon
after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
entry can still modify old_page even after it is copied to
new_page by wp_page_copy, thus causing a corruption.
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
---
mm/memory.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/mm/memory.c b/mm/memory.c
index 52080e4..1ea168ff 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
return VM_FAULT_RETRY;
}
+ /*
+ * Discard tlb entries created before ptep_set_wrprotect
+ * in copy_one_pte
+ */
+ if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
+ flush_tlb_page(vmf.vma, address);
+
mem_cgroup_oom_enable();
ret = handle_pte_fault(&vmf);
mem_cgroup_oom_disable();
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation
^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-14 13:19 ` Vinayak Menon
@ 2019-01-15 8:24 ` Laurent Dufour
2019-01-16 11:41 ` Vinayak Menon
2019-01-16 11:41 ` Vinayak Menon
0 siblings, 2 replies; 46+ messages in thread
From: Laurent Dufour @ 2019-01-15 8:24 UTC (permalink / raw)
To: Vinayak Menon; +Cc: Linux-MM, charante, Ganesh Mahendran
[-- Attachment #1: Type: text/plain, Size: 3581 bytes --]
Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>> Hi Laurent,
>>
>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>
>
> With the patch below, we don't hit the issue.
>
> From: Vinayak Menon <vinmenon@codeaurora.org>
> Date: Mon, 14 Jan 2019 16:06:34 +0530
> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>
> It is observed that the following scenario results in
> threads A and B of process 1 blocking on pthread_mutex_lock
> forever after few iterations.
>
> CPU 1 CPU 2 CPU 3
> Process 1, Process 1, Process 1,
> Thread A Thread B Thread C
>
> while (1) { while (1) { while(1) {
> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
> } }
>
> When from thread C, copy_one_pte write-protects the parent pte
> (of lock l), stale tlb entries can exist with write permissions
> on one of the CPUs at least. This can create a problem if one
> of the threads A or B hits the write fault. Though dup_mmap calls
> flush_tlb_mm after copy_page_range, since speculative page fault
> does not take mmap_sem it can proceed further fixing a fault soon
> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
> entry can still modify old_page even after it is copied to
> new_page by wp_page_copy, thus causing a corruption.
Nice catch and thanks for your investigation!
There is a real synchronization issue here between copy_page_range() and
the speculative page fault handler. I didn't get it on PowerVM since the
TLB are flushed when arch_exit_lazy_mode() is called in
copy_page_range() but now, I can get it when running on x86_64.
> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
> ---
> mm/memory.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 52080e4..1ea168ff 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
> return VM_FAULT_RETRY;
> }
>
> + /*
> + * Discard tlb entries created before ptep_set_wrprotect
> + * in copy_one_pte
> + */
> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
> + flush_tlb_page(vmf.vma, address);
> +
> mem_cgroup_oom_enable();
> ret = handle_pte_fault(&vmf);
> mem_cgroup_oom_disable();
Your patch is fixing the race but I'm wondering about the cost of these
tlb flushes. Here we are flushing on a per page basis (architecture like
x86_64 are smarter and flush more pages) but there is a request to flush
a range of tlb entries each time a cow page is newly touched. I think
there could be some bad impact here.
Another option would be to flush the range in copy_pte_range() before
unlocking the page table lock. This will flush entries flush_tlb_mm()
would later handle in dup_mmap() but that will be called once per fork
per cow VMA.
I tried the attached patch which seems to fix the issue on x86_64. Could
you please give it a try on arm64 ?
Thanks,
Laurent.
[-- Attachment #2: 0001-mm-flush-TLB-once-pages-are-copied-when-SPF-is-on.patch --]
[-- Type: text/plain, Size: 2137 bytes --]
From 9847338187c5c7e2d387d14765452d00fa60981e Mon Sep 17 00:00:00 2001
From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Date: Mon, 14 Jan 2019 18:35:39 +0100
Subject: [PATCH] mm: flush TLB once pages are copied when SPF is on
Vinayak Menon reported that the following scenario results in
threads A and B of process 1 blocking on pthread_mutex_lock
forever after few iterations.
CPU 1 CPU 2 CPU 3
Process 1, Process 1, Process 1,
Thread A Thread B Thread C
while (1) { while (1) { while(1) {
pthread_mutex_lock(l) pthread_mutex_lock(l) fork
pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
} }
When from thread C, copy_one_pte write-protects the parent pte
(of lock l), stale tlb entries can exist with write permissions
on one of the CPUs at least. This can create a problem if one
of the threads A or B hits the write fault. Though dup_mmap calls
flush_tlb_mm after copy_page_range, since speculative page fault
does not take mmap_sem it can proceed further fixing a fault soon
after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
entry can still modify old_page even after it is copied to
new_page by wp_page_copy, thus causing a corruption.
Reported-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
mm/memory.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/mm/memory.c b/mm/memory.c
index 48e1cf0a54ef..b7501294e0a0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1112,6 +1112,15 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
+
+ /*
+ * Prevent the page fault handler to copy the page while stale tlb entry
+ * are still not flushed.
+ */
+ if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT) &&
+ is_cow_mapping(vma->vm_flags))
+ flush_tlb_range(vma, addr, end);
+
spin_unlock(src_ptl);
pte_unmap(orig_src_pte);
add_mm_rss_vec(dst_mm, rss);
--
2.20.1
^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-15 8:24 ` Laurent Dufour
@ 2019-01-16 11:41 ` Vinayak Menon
2019-01-16 13:31 ` Laurent Dufour
2019-01-16 11:41 ` Vinayak Menon
1 sibling, 1 reply; 46+ messages in thread
From: Vinayak Menon @ 2019-01-16 11:41 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Linux-MM, charante, Ganesh Mahendran
On 1/15/2019 1:54 PM, Laurent Dufour wrote:
> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>> Hi Laurent,
>>>
>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>
>>
>> With the patch below, we don't hit the issue.
>>
>> From: Vinayak Menon <vinmenon@codeaurora.org>
>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>
>> It is observed that the following scenario results in
>> threads A and B of process 1 blocking on pthread_mutex_lock
>> forever after few iterations.
>>
>> CPU 1 CPU 2 CPU 3
>> Process 1, Process 1, Process 1,
>> Thread A Thread B Thread C
>>
>> while (1) { while (1) { while(1) {
>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>> } }
>>
>> When from thread C, copy_one_pte write-protects the parent pte
>> (of lock l), stale tlb entries can exist with write permissions
>> on one of the CPUs at least. This can create a problem if one
>> of the threads A or B hits the write fault. Though dup_mmap calls
>> flush_tlb_mm after copy_page_range, since speculative page fault
>> does not take mmap_sem it can proceed further fixing a fault soon
>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>> entry can still modify old_page even after it is copied to
>> new_page by wp_page_copy, thus causing a corruption.
>
> Nice catch and thanks for your investigation!
>
> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>
>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>> ---
>> mm/memory.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 52080e4..1ea168ff 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>> return VM_FAULT_RETRY;
>> }
>>
>> + /*
>> + * Discard tlb entries created before ptep_set_wrprotect
>> + * in copy_one_pte
>> + */
>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>> + flush_tlb_page(vmf.vma, address);
>> +
>> mem_cgroup_oom_enable();
>> ret = handle_pte_fault(&vmf);
>> mem_cgroup_oom_disable();
>
> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>
> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>
> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>
Your patch works fine on arm64 with a minor change. Thanks Laurent.
diff --git a/mm/memory.c b/mm/memory.c
index 52080e4..4767095 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1087,6 +1087,7 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
spinlock_t *src_ptl, *dst_ptl;
int progress = 0;
int rss[NR_MM_COUNTERS];
+ unsigned long orig_addr = addr;
swp_entry_t entry = (swp_entry_t){0};
again:
@@ -1125,6 +1126,15 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
+
+ /*
+ * Prevent the page fault handler to copy the page while stale tlb entry
+ * are still not flushed.
+ */
+ if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT) &&
+ is_cow_mapping(vma->vm_flags))
+ flush_tlb_range(vma, orig_addr, end);
+
spin_unlock(src_ptl);
pte_unmap(orig_src_pte);
add_mm_rss_vec(dst_mm, rss);
Thanks,
Vinayak
^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-15 8:24 ` Laurent Dufour
2019-01-16 11:41 ` Vinayak Menon
@ 2019-01-16 11:41 ` Vinayak Menon
2019-01-17 15:51 ` zhong jiang
1 sibling, 1 reply; 46+ messages in thread
From: Vinayak Menon @ 2019-01-16 11:41 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Linux-MM, charante, Ganesh Mahendran
On 1/15/2019 1:54 PM, Laurent Dufour wrote:
> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>> Hi Laurent,
>>>
>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>
>>
>> With the patch below, we don't hit the issue.
>>
>> From: Vinayak Menon <vinmenon@codeaurora.org>
>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>
>> It is observed that the following scenario results in
>> threads A and B of process 1 blocking on pthread_mutex_lock
>> forever after few iterations.
>>
>> CPU 1 CPU 2 CPU 3
>> Process 1, Process 1, Process 1,
>> Thread A Thread B Thread C
>>
>> while (1) { while (1) { while(1) {
>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>> } }
>>
>> When from thread C, copy_one_pte write-protects the parent pte
>> (of lock l), stale tlb entries can exist with write permissions
>> on one of the CPUs at least. This can create a problem if one
>> of the threads A or B hits the write fault. Though dup_mmap calls
>> flush_tlb_mm after copy_page_range, since speculative page fault
>> does not take mmap_sem it can proceed further fixing a fault soon
>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>> entry can still modify old_page even after it is copied to
>> new_page by wp_page_copy, thus causing a corruption.
>
> Nice catch and thanks for your investigation!
>
> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>
>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>> ---
>> mm/memory.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 52080e4..1ea168ff 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>> return VM_FAULT_RETRY;
>> }
>>
>> + /*
>> + * Discard tlb entries created before ptep_set_wrprotect
>> + * in copy_one_pte
>> + */
>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>> + flush_tlb_page(vmf.vma, address);
>> +
>> mem_cgroup_oom_enable();
>> ret = handle_pte_fault(&vmf);
>> mem_cgroup_oom_disable();
>
> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>
> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>
> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>
Your patch works fine on arm64 with a minor change. Thanks Laurent.
diff --git a/mm/memory.c b/mm/memory.c
index 52080e4..4767095 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1087,6 +1087,7 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
spinlock_t *src_ptl, *dst_ptl;
int progress = 0;
int rss[NR_MM_COUNTERS];
+ unsigned long orig_addr = addr;
swp_entry_t entry = (swp_entry_t){0};
again:
@@ -1125,6 +1126,15 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
+
+ /*
+ * Prevent the page fault handler to copy the page while stale tlb entry
+ * are still not flushed.
+ */
+ if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT) &&
+ is_cow_mapping(vma->vm_flags))
+ flush_tlb_range(vma, orig_addr, end);
+
spin_unlock(src_ptl);
pte_unmap(orig_src_pte);
add_mm_rss_vec(dst_mm, rss);
Thanks,
Vinayak
^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-16 11:41 ` Vinayak Menon
@ 2019-01-16 13:31 ` Laurent Dufour
0 siblings, 0 replies; 46+ messages in thread
From: Laurent Dufour @ 2019-01-16 13:31 UTC (permalink / raw)
To: Vinayak Menon; +Cc: Linux-MM, charante, Ganesh Mahendran
Le 16/01/2019 à 12:41, Vinayak Menon a écrit :
>
> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>> Hi Laurent,
>>>>
>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>
>>>
>>> With the patch below, we don't hit the issue.
>>>
>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>
>>> It is observed that the following scenario results in
>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>> forever after few iterations.
>>>
>>> CPU 1 CPU 2 CPU 3
>>> Process 1, Process 1, Process 1,
>>> Thread A Thread B Thread C
>>>
>>> while (1) { while (1) { while(1) {
>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>> } }
>>>
>>> When from thread C, copy_one_pte write-protects the parent pte
>>> (of lock l), stale tlb entries can exist with write permissions
>>> on one of the CPUs at least. This can create a problem if one
>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>> does not take mmap_sem it can proceed further fixing a fault soon
>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>> entry can still modify old_page even after it is copied to
>>> new_page by wp_page_copy, thus causing a corruption.
>>
>> Nice catch and thanks for your investigation!
>>
>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>
>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>> ---
>>> mm/memory.c | 7 +++++++
>>> 1 file changed, 7 insertions(+)
>>>
>>> diff --git a/mm/memory.c b/mm/memory.c
>>> index 52080e4..1ea168ff 100644
>>> --- a/mm/memory.c
>>> +++ b/mm/memory.c
>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>> return VM_FAULT_RETRY;
>>> }
>>>
>>> + /*
>>> + * Discard tlb entries created before ptep_set_wrprotect
>>> + * in copy_one_pte
>>> + */
>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>> + flush_tlb_page(vmf.vma, address);
>>> +
>>> mem_cgroup_oom_enable();
>>> ret = handle_pte_fault(&vmf);
>>> mem_cgroup_oom_disable();
>>
>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>
>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>
>
> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
I think this should be less costly to do it per vma at the time of the
fork instead of per page hit once the fork has been done, since this
will happen in both the forked task and the forking one (the COW pages
are concerning the both sides of the fork).
>>
>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>
>
> Your patch works fine on arm64 with a minor change. Thanks Laurent.
Yup my mistake !
I tried to shrink the patch after testing it, sounds that I shrunk it
far too much...
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 52080e4..4767095 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1087,6 +1087,7 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
> spinlock_t *src_ptl, *dst_ptl;
> int progress = 0;
> int rss[NR_MM_COUNTERS];
> + unsigned long orig_addr = addr;
> swp_entry_t entry = (swp_entry_t){0};
>
> again:
> @@ -1125,6 +1126,15 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
> } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
>
> arch_leave_lazy_mmu_mode();
> +
> + /*
> + * Prevent the page fault handler to copy the page while stale tlb entry
> + * are still not flushed.
> + */
> + if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT) &&
> + is_cow_mapping(vma->vm_flags))
> + flush_tlb_range(vma, orig_addr, end);
> +
> spin_unlock(src_ptl);
> pte_unmap(orig_src_pte);
> add_mm_rss_vec(dst_mm, rss);
>
> Thanks,
>
> Vinayak
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-16 11:41 ` Vinayak Menon
@ 2019-01-17 15:51 ` zhong jiang
2019-01-17 15:51 ` zhong jiang
` (2 more replies)
0 siblings, 3 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-17 15:51 UTC (permalink / raw)
To: Vinayak Menon, Laurent Dufour; +Cc: Linux-MM, charante, Ganesh Mahendran
On 2019/1/16 19:41, Vinayak Menon wrote:
> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>> Hi Laurent,
>>>>
>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>
>>> With the patch below, we don't hit the issue.
>>>
>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>
>>> It is observed that the following scenario results in
>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>> forever after few iterations.
>>>
>>> CPU 1 CPU 2 CPU 3
>>> Process 1, Process 1, Process 1,
>>> Thread A Thread B Thread C
>>>
>>> while (1) { while (1) { while(1) {
>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>> } }
>>>
>>> When from thread C, copy_one_pte write-protects the parent pte
>>> (of lock l), stale tlb entries can exist with write permissions
>>> on one of the CPUs at least. This can create a problem if one
>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>> does not take mmap_sem it can proceed further fixing a fault soon
>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>> entry can still modify old_page even after it is copied to
>>> new_page by wp_page_copy, thus causing a corruption.
>> Nice catch and thanks for your investigation!
>>
>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>
>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>> ---
>>> mm/memory.c | 7 +++++++
>>> 1 file changed, 7 insertions(+)
>>>
>>> diff --git a/mm/memory.c b/mm/memory.c
>>> index 52080e4..1ea168ff 100644
>>> --- a/mm/memory.c
>>> +++ b/mm/memory.c
>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>> return VM_FAULT_RETRY;
>>> }
>>>
>>> + /*
>>> + * Discard tlb entries created before ptep_set_wrprotect
>>> + * in copy_one_pte
>>> + */
>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>> + flush_tlb_page(vmf.vma, address);
>>> +
>>> mem_cgroup_oom_enable();
>>> ret = handle_pte_fault(&vmf);
>>> mem_cgroup_oom_disable();
>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>
>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>
> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>
>
>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>
> Your patch works fine on arm64 with a minor change. Thanks Laurent.
Hi, Vinayak and Laurent
I think the below change will impact the performance significantly. Becuase most of process has many
vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
call the flush_tlb_mm later.
I think we can try the following way to do.
vm_write_begin(vma)
copy_pte_range
vm_write_end(vma)
The speculative page fault will return to grap the mmap_sem to run the nromal path.
Any thought?
Thanks,
zhong jiang
> diff --git a/mm/memory.c b/mm/memory.c
> index 52080e4..4767095 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1087,6 +1087,7 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
> spinlock_t *src_ptl, *dst_ptl;
> int progress = 0;
> int rss[NR_MM_COUNTERS];
> + unsigned long orig_addr = addr;
> swp_entry_t entry = (swp_entry_t){0};
>
> again:
> @@ -1125,6 +1126,15 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
> } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
>
> arch_leave_lazy_mmu_mode();
> +
> + /*
> + * Prevent the page fault handler to copy the page while stale tlb entry
> + * are still not flushed.
> + */
> + if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT) &&
> + is_cow_mapping(vma->vm_flags))
> + flush_tlb_range(vma, orig_addr, end);
> +
> spin_unlock(src_ptl);
> pte_unmap(orig_src_pte);
> add_mm_rss_vec(dst_mm, rss);
>
> Thanks,
>
> Vinayak
>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-17 15:51 ` zhong jiang
@ 2019-01-17 15:51 ` zhong jiang
2019-01-18 9:29 ` Laurent Dufour
2019-01-18 16:24 ` Laurent Dufour
2 siblings, 0 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-17 15:51 UTC (permalink / raw)
To: Vinayak Menon, Laurent Dufour; +Cc: Linux-MM, charante, Ganesh Mahendran
On 2019/1/16 19:41, Vinayak Menon wrote:
> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>> Hi Laurent,
>>>>
>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>
>>> With the patch below, we don't hit the issue.
>>>
>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>
>>> It is observed that the following scenario results in
>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>> forever after few iterations.
>>>
>>> CPU 1 CPU 2 CPU 3
>>> Process 1, Process 1, Process 1,
>>> Thread A Thread B Thread C
>>>
>>> while (1) { while (1) { while(1) {
>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>> } }
>>>
>>> When from thread C, copy_one_pte write-protects the parent pte
>>> (of lock l), stale tlb entries can exist with write permissions
>>> on one of the CPUs at least. This can create a problem if one
>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>> does not take mmap_sem it can proceed further fixing a fault soon
>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>> entry can still modify old_page even after it is copied to
>>> new_page by wp_page_copy, thus causing a corruption.
>> Nice catch and thanks for your investigation!
>>
>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>
>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>> ---
>>> mm/memory.c | 7 +++++++
>>> 1 file changed, 7 insertions(+)
>>>
>>> diff --git a/mm/memory.c b/mm/memory.c
>>> index 52080e4..1ea168ff 100644
>>> --- a/mm/memory.c
>>> +++ b/mm/memory.c
>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>> return VM_FAULT_RETRY;
>>> }
>>>
>>> + /*
>>> + * Discard tlb entries created before ptep_set_wrprotect
>>> + * in copy_one_pte
>>> + */
>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>> + flush_tlb_page(vmf.vma, address);
>>> +
>>> mem_cgroup_oom_enable();
>>> ret = handle_pte_fault(&vmf);
>>> mem_cgroup_oom_disable();
>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>
>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>
> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>
>
>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>
> Your patch works fine on arm64 with a minor change. Thanks Laurent.
Hi, Vinayak and Laurent
I think the below change will impact the performance significantly. Becuase most of process has many
vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
call the flush_tlb_mm later.
I think we can try the following way to do.
vm_write_begin(vma)
copy_pte_range
vm_write_end(vma)
The speculative page fault will return to grap the mmap_sem to run the nromal path.
Any thought?
Thanks,
zhong jiang
> diff --git a/mm/memory.c b/mm/memory.c
> index 52080e4..4767095 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1087,6 +1087,7 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
> spinlock_t *src_ptl, *dst_ptl;
> int progress = 0;
> int rss[NR_MM_COUNTERS];
> + unsigned long orig_addr = addr;
> swp_entry_t entry = (swp_entry_t){0};
>
> again:
> @@ -1125,6 +1126,15 @@ static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
> } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
>
> arch_leave_lazy_mmu_mode();
> +
> + /*
> + * Prevent the page fault handler to copy the page while stale tlb entry
> + * are still not flushed.
> + */
> + if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT) &&
> + is_cow_mapping(vma->vm_flags))
> + flush_tlb_range(vma, orig_addr, end);
> +
> spin_unlock(src_ptl);
> pte_unmap(orig_src_pte);
> add_mm_rss_vec(dst_mm, rss);
>
> Thanks,
>
> Vinayak
>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-17 15:51 ` zhong jiang
2019-01-17 15:51 ` zhong jiang
@ 2019-01-18 9:29 ` Laurent Dufour
2019-01-18 15:41 ` zhong jiang
2019-01-18 16:24 ` Laurent Dufour
2 siblings, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2019-01-18 9:29 UTC (permalink / raw)
To: zhong jiang, Vinayak Menon; +Cc: Linux-MM, charante, Ganesh Mahendran
Le 17/01/2019 à 16:51, zhong jiang a écrit :
> On 2019/1/16 19:41, Vinayak Menon wrote:
>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>> Hi Laurent,
>>>>>
>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>
>>>> With the patch below, we don't hit the issue.
>>>>
>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>
>>>> It is observed that the following scenario results in
>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>> forever after few iterations.
>>>>
>>>> CPU 1 CPU 2 CPU 3
>>>> Process 1, Process 1, Process 1,
>>>> Thread A Thread B Thread C
>>>>
>>>> while (1) { while (1) { while(1) {
>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>> } }
>>>>
>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>> (of lock l), stale tlb entries can exist with write permissions
>>>> on one of the CPUs at least. This can create a problem if one
>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>> entry can still modify old_page even after it is copied to
>>>> new_page by wp_page_copy, thus causing a corruption.
>>> Nice catch and thanks for your investigation!
>>>
>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>
>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>> ---
>>>> mm/memory.c | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>> index 52080e4..1ea168ff 100644
>>>> --- a/mm/memory.c
>>>> +++ b/mm/memory.c
>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>> return VM_FAULT_RETRY;
>>>> }
>>>>
>>>> + /*
>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>> + * in copy_one_pte
>>>> + */
>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>> + flush_tlb_page(vmf.vma, address);
>>>> +
>>>> mem_cgroup_oom_enable();
>>>> ret = handle_pte_fault(&vmf);
>>>> mem_cgroup_oom_disable();
>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>
>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>
>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>
>>
>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>
>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
> Hi, Vinayak and Laurent
>
> I think the below change will impact the performance significantly. Becuase most of process has many
> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
> call the flush_tlb_mm later.
>
> I think we can try the following way to do.
>
> vm_write_begin(vma)
> copy_pte_range
> vm_write_end(vma)
>
> The speculative page fault will return to grap the mmap_sem to run the nromal path.
> Any thought?
Hi Zhong,
I agree that flushing the TLB could have a bad impact on the
performance, but tagging the VMA when copy_pte_range() is not fixing the
issue as the VMA must be flagged until the PTE are flushed.
Here is what happens:
CPU A CPU B CPU C
fork()
copy_pte_range()
set PTE rdonly
got to next VMA...
. PTE is seen rdonly PTE still writable
. thread is writing to page
. -> page fault
. copy the page Thread writes to page
. . -> no page fault
. update the PTE
. flush TLB for that PTE
flush TLB PTE are now rdonly
So the write done by the CPU C is interfering with the page copy
operation done by CPU B, leading to the data corruption.
Flushing the PTE in copy_pte_range() is fixing the issue as the CPU C is
seeing the PTE as rdonly earlier. But this impacts performance.
Another option, I'll work on is to flag _all the COW eligible_ VMA
before starting copying them and until the PTE are flushed on the CPU A.
This way when the CPU B will page fault the speculative handler will
abort because the VMA is in the way to be touched.
But I need to ensure that all the calls to copy_pte_range() are handling
this correctly.
Laurent.
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-18 9:29 ` Laurent Dufour
@ 2019-01-18 15:41 ` zhong jiang
2019-01-18 15:41 ` zhong jiang
2019-01-18 15:51 ` Laurent Dufour
0 siblings, 2 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-18 15:41 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/18 17:29, Laurent Dufour wrote:
> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>
>>>>> With the patch below, we don't hit the issue.
>>>>>
>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>
>>>>> It is observed that the following scenario results in
>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>> forever after few iterations.
>>>>>
>>>>> CPU 1 CPU 2 CPU 3
>>>>> Process 1, Process 1, Process 1,
>>>>> Thread A Thread B Thread C
>>>>>
>>>>> while (1) { while (1) { while(1) {
>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>> } }
>>>>>
>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>> on one of the CPUs at least. This can create a problem if one
>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>> entry can still modify old_page even after it is copied to
>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>> Nice catch and thanks for your investigation!
>>>>
>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>
>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> ---
>>>>> mm/memory.c | 7 +++++++
>>>>> 1 file changed, 7 insertions(+)
>>>>>
>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>> index 52080e4..1ea168ff 100644
>>>>> --- a/mm/memory.c
>>>>> +++ b/mm/memory.c
>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>> return VM_FAULT_RETRY;
>>>>> }
>>>>>
>>>>> + /*
>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>> + * in copy_one_pte
>>>>> + */
>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>> + flush_tlb_page(vmf.vma, address);
>>>>> +
>>>>> mem_cgroup_oom_enable();
>>>>> ret = handle_pte_fault(&vmf);
>>>>> mem_cgroup_oom_disable();
>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>
>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>
>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>
>>>
>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>
>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>> Hi, Vinayak and Laurent
>>
>> I think the below change will impact the performance significantly. Becuase most of process has many
>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>> call the flush_tlb_mm later.
>>
>> I think we can try the following way to do.
>>
>> vm_write_begin(vma)
>> copy_pte_range
>> vm_write_end(vma)
>>
>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>> Any thought?
>
> Hi Zhong,
>
> I agree that flushing the TLB could have a bad impact on the performance, but tagging the VMA when copy_pte_range() is not fixing the issue as the VMA must be flagged until the PTE are flushed.
>
> Here is what happens:
>
> CPU A CPU B CPU C
> fork()
> copy_pte_range()
> set PTE rdonly
> got to next VMA...
> . PTE is seen rdonly PTE still writable
> . thread is writing to page
> . -> page fault
> . copy the page Thread writes to page
> . . -> no page fault
> . update the PTE
> . flush TLB for that PTE
> flush TLB PTE are now rdonly
>
> So the write done by the CPU C is interfering with the page copy operation done by CPU B, leading to the data corruption.
>
I want to know the case if the CPU B has finished in front of the CPU C that the data still is vaild ?
This is to say, the old_page will be changed from other cpu because of the access from other cpu.
Maybe this is a stupid qestion :-)
Thanks,
zhong jiang.
> Flushing the PTE in copy_pte_range() is fixing the issue as the CPU C is seeing the PTE as rdonly earlier. But this impacts performance.
>
> Another option, I'll work on is to flag _all the COW eligible_ VMA before starting copying them and until the PTE are flushed on the CPU A.
> This way when the CPU B will page fault the speculative handler will abort because the VMA is in the way to be touched.
>
> But I need to ensure that all the calls to copy_pte_range() are handling this correctly.
>
> Laurent.
>
>
> .
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-18 15:41 ` zhong jiang
@ 2019-01-18 15:41 ` zhong jiang
2019-01-18 15:51 ` Laurent Dufour
1 sibling, 0 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-18 15:41 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/18 17:29, Laurent Dufour wrote:
> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>
>>>>> With the patch below, we don't hit the issue.
>>>>>
>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>
>>>>> It is observed that the following scenario results in
>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>> forever after few iterations.
>>>>>
>>>>> CPU 1 CPU 2 CPU 3
>>>>> Process 1, Process 1, Process 1,
>>>>> Thread A Thread B Thread C
>>>>>
>>>>> while (1) { while (1) { while(1) {
>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>> } }
>>>>>
>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>> on one of the CPUs at least. This can create a problem if one
>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>> entry can still modify old_page even after it is copied to
>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>> Nice catch and thanks for your investigation!
>>>>
>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>
>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> ---
>>>>> mm/memory.c | 7 +++++++
>>>>> 1 file changed, 7 insertions(+)
>>>>>
>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>> index 52080e4..1ea168ff 100644
>>>>> --- a/mm/memory.c
>>>>> +++ b/mm/memory.c
>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>> return VM_FAULT_RETRY;
>>>>> }
>>>>>
>>>>> + /*
>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>> + * in copy_one_pte
>>>>> + */
>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>> + flush_tlb_page(vmf.vma, address);
>>>>> +
>>>>> mem_cgroup_oom_enable();
>>>>> ret = handle_pte_fault(&vmf);
>>>>> mem_cgroup_oom_disable();
>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>
>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>
>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>
>>>
>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>
>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>> Hi, Vinayak and Laurent
>>
>> I think the below change will impact the performance significantly. Becuase most of process has many
>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>> call the flush_tlb_mm later.
>>
>> I think we can try the following way to do.
>>
>> vm_write_begin(vma)
>> copy_pte_range
>> vm_write_end(vma)
>>
>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>> Any thought?
>
> Hi Zhong,
>
> I agree that flushing the TLB could have a bad impact on the performance, but tagging the VMA when copy_pte_range() is not fixing the issue as the VMA must be flagged until the PTE are flushed.
>
> Here is what happens:
>
> CPU A CPU B CPU C
> fork()
> copy_pte_range()
> set PTE rdonly
> got to next VMA...
> . PTE is seen rdonly PTE still writable
> . thread is writing to page
> . -> page fault
> . copy the page Thread writes to page
> . . -> no page fault
> . update the PTE
> . flush TLB for that PTE
> flush TLB PTE are now rdonly
>
> So the write done by the CPU C is interfering with the page copy operation done by CPU B, leading to the data corruption.
>
I want to know the case if the CPU B has finished in front of the CPU C that the data still is vaild ?
This is to say, the old_page will be changed from other cpu because of the access from other cpu.
Maybe this is a stupid qestion :-)
Thanks,
zhong jiang.
> Flushing the PTE in copy_pte_range() is fixing the issue as the CPU C is seeing the PTE as rdonly earlier. But this impacts performance.
>
> Another option, I'll work on is to flag _all the COW eligible_ VMA before starting copying them and until the PTE are flushed on the CPU A.
> This way when the CPU B will page fault the speculative handler will abort because the VMA is in the way to be touched.
>
> But I need to ensure that all the calls to copy_pte_range() are handling this correctly.
>
> Laurent.
>
>
> .
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-18 15:41 ` zhong jiang
2019-01-18 15:41 ` zhong jiang
@ 2019-01-18 15:51 ` Laurent Dufour
1 sibling, 0 replies; 46+ messages in thread
From: Laurent Dufour @ 2019-01-18 15:51 UTC (permalink / raw)
To: zhong jiang; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
Le 18/01/2019 à 16:41, zhong jiang a écrit :
> On 2019/1/18 17:29, Laurent Dufour wrote:
>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>> Hi Laurent,
>>>>>>>
>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>
>>>>>> With the patch below, we don't hit the issue.
>>>>>>
>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>
>>>>>> It is observed that the following scenario results in
>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>> forever after few iterations.
>>>>>>
>>>>>> CPU 1 CPU 2 CPU 3
>>>>>> Process 1, Process 1, Process 1,
>>>>>> Thread A Thread B Thread C
>>>>>>
>>>>>> while (1) { while (1) { while(1) {
>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>> } }
>>>>>>
>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>> entry can still modify old_page even after it is copied to
>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>> Nice catch and thanks for your investigation!
>>>>>
>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>
>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>> ---
>>>>>> mm/memory.c | 7 +++++++
>>>>>> 1 file changed, 7 insertions(+)
>>>>>>
>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>> index 52080e4..1ea168ff 100644
>>>>>> --- a/mm/memory.c
>>>>>> +++ b/mm/memory.c
>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>> return VM_FAULT_RETRY;
>>>>>> }
>>>>>>
>>>>>> + /*
>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>> + * in copy_one_pte
>>>>>> + */
>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>> +
>>>>>> mem_cgroup_oom_enable();
>>>>>> ret = handle_pte_fault(&vmf);
>>>>>> mem_cgroup_oom_disable();
>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>
>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>
>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>
>>>>
>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>
>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>> Hi, Vinayak and Laurent
>>>
>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>> call the flush_tlb_mm later.
>>>
>>> I think we can try the following way to do.
>>>
>>> vm_write_begin(vma)
>>> copy_pte_range
>>> vm_write_end(vma)
>>>
>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>> Any thought?
>>
>> Hi Zhong,
>>
>> I agree that flushing the TLB could have a bad impact on the performance, but tagging the VMA when copy_pte_range() is not fixing the issue as the VMA must be flagged until the PTE are flushed.
>>
>> Here is what happens:
>>
>> CPU A CPU B CPU C
>> fork()
>> copy_pte_range()
>> set PTE rdonly
>> got to next VMA...
>> . PTE is seen rdonly PTE still writable
>> . thread is writing to page
>> . -> page fault
>> . copy the page Thread writes to page
>> . . -> no page fault
>> . update the PTE
>> . flush TLB for that PTE
>> flush TLB PTE are now rdonly
>>
>> So the write done by the CPU C is interfering with the page copy operation done by CPU B, leading to the data corruption.
>>
> I want to know the case if the CPU B has finished in front of the CPU C that the data still is vaild ?
If the CPU B has done the flush TLB then the CPU C will write data to
the right page. If the CPU B has not yet done the flush of the TLB as
the time the CPU C is writing data, then this roughly the same issue.
Anyway this is fixed with the patch I'm about to sent for testing on arm64.
Cheers,
Laurent.
>
> This is to say, the old_page will be changed from other cpu because of the access from other cpu.
>
> Maybe this is a stupid qestion :-)
>
> Thanks,
> zhong jiang.
>> Flushing the PTE in copy_pte_range() is fixing the issue as the CPU C is seeing the PTE as rdonly earlier. But this impacts performance.
>>
>> Another option, I'll work on is to flag _all the COW eligible_ VMA before starting copying them and until the PTE are flushed on the CPU A.
>> This way when the CPU B will page fault the speculative handler will abort because the VMA is in the way to be touched.
>>
>> But I need to ensure that all the calls to copy_pte_range() are handling this correctly.
>>
>> Laurent.
>>
>>
>> .
>>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-17 15:51 ` zhong jiang
2019-01-17 15:51 ` zhong jiang
2019-01-18 9:29 ` Laurent Dufour
@ 2019-01-18 16:24 ` Laurent Dufour
2019-01-19 17:05 ` zhong jiang
2019-01-22 16:22 ` zhong jiang
2 siblings, 2 replies; 46+ messages in thread
From: Laurent Dufour @ 2019-01-18 16:24 UTC (permalink / raw)
To: zhong jiang, Vinayak Menon; +Cc: Linux-MM, charante, Ganesh Mahendran
[-- Attachment #1: Type: text/plain, Size: 4671 bytes --]
Le 17/01/2019 à 16:51, zhong jiang a écrit :
> On 2019/1/16 19:41, Vinayak Menon wrote:
>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>> Hi Laurent,
>>>>>
>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>
>>>> With the patch below, we don't hit the issue.
>>>>
>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>
>>>> It is observed that the following scenario results in
>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>> forever after few iterations.
>>>>
>>>> CPU 1 CPU 2 CPU 3
>>>> Process 1, Process 1, Process 1,
>>>> Thread A Thread B Thread C
>>>>
>>>> while (1) { while (1) { while(1) {
>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>> } }
>>>>
>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>> (of lock l), stale tlb entries can exist with write permissions
>>>> on one of the CPUs at least. This can create a problem if one
>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>> entry can still modify old_page even after it is copied to
>>>> new_page by wp_page_copy, thus causing a corruption.
>>> Nice catch and thanks for your investigation!
>>>
>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>
>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>> ---
>>>> mm/memory.c | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>> index 52080e4..1ea168ff 100644
>>>> --- a/mm/memory.c
>>>> +++ b/mm/memory.c
>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>> return VM_FAULT_RETRY;
>>>> }
>>>>
>>>> + /*
>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>> + * in copy_one_pte
>>>> + */
>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>> + flush_tlb_page(vmf.vma, address);
>>>> +
>>>> mem_cgroup_oom_enable();
>>>> ret = handle_pte_fault(&vmf);
>>>> mem_cgroup_oom_disable();
>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>
>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>
>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>
>>
>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>
>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
> Hi, Vinayak and Laurent
>
> I think the below change will impact the performance significantly. Becuase most of process has many
> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
> call the flush_tlb_mm later.
>
> I think we can try the following way to do.
>
> vm_write_begin(vma)
> copy_pte_range
> vm_write_end(vma)
>
> The speculative page fault will return to grap the mmap_sem to run the nromal path.
> Any thought?
Here is a new version of the patch fixing this issue. There is no
additional TLB flush, all the fix is belonging on vm_write_{begin,end}
calls.
I did some test on x86_64 and PowerPC but that needs to be double check
on arm64.
Vinayak, Zhong, could you please give it a try ?
Thanks,
Laurent.
[-- Attachment #2: 0001-mm-protect-against-PTE-changes-done-by-dup_mmap.patch --]
[-- Type: text/plain, Size: 4050 bytes --]
From 3be977febb9ff93d516a2d222cca4b5a52472a9f Mon Sep 17 00:00:00 2001
From: Laurent Dufour <ldufour@linux.ibm.com>
Date: Fri, 18 Jan 2019 16:19:08 +0100
Subject: [PATCH] mm: protect against PTE changes done by dup_mmap()
Vinayak Menon and Ganesh Mahendran reported that the following scenario may
lead to thread being blocked due to data corruption:
CPU 1 CPU 2 CPU 3
Process 1, Process 1, Process 1,
Thread A Thread B Thread C
while (1) { while (1) { while(1) {
pthread_mutex_lock(l) pthread_mutex_lock(l) fork
pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
} }
In the details this happens because :
CPU 1 CPU 2 CPU 3
fork()
copy_pte_range()
set PTE rdonly
got to next VMA...
. PTE is seen rdonly PTE still writable
. thread is writing to page
. -> page fault
. copy the page Thread writes to page
. . -> no page fault
. update the PTE
. flush TLB for that PTE
flush TLB PTE are now rdonly
So the write done by the CPU 3 is interfering with the page copy operation
done by CPU 2, leading to the data corruption.
To avoid this we mark all the VMA involved in the COW mechanism as changing
by calling vm_write_begin(). This ensures that the speculative page fault
handler will not try to handle a fault on these pages.
The marker is set until the TLB is flushed, ensuring that all the CPUs will
now see the PTE as not writable.
Once the TLB is flush, the marker is removed by calling vm_write_end().
The variable last is used to keep tracked of the latest VMA marked to
handle the error path where part of the VMA may have been marked.
Reported-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Reported-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
---
kernel/fork.c | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index f1258c2ade09..39854b97d06a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -395,7 +395,7 @@ EXPORT_SYMBOL(free_task);
static __latent_entropy int dup_mmap(struct mm_struct *mm,
struct mm_struct *oldmm)
{
- struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
+ struct vm_area_struct *mpnt, *tmp, *prev, **pprev, *last = NULL;
struct rb_node **rb_link, *rb_parent;
int retval;
unsigned long charge;
@@ -515,8 +515,18 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
rb_parent = &tmp->vm_rb;
mm->map_count++;
- if (!(tmp->vm_flags & VM_WIPEONFORK))
+ if (!(tmp->vm_flags & VM_WIPEONFORK)) {
+ if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT)) {
+ /*
+ * Mark this VMA as changing to prevent the
+ * speculative page fault hanlder to process
+ * it until the TLB are flushed below.
+ */
+ last = mpnt;
+ vm_write_begin(mpnt);
+ }
retval = copy_page_range(mm, oldmm, mpnt);
+ }
if (tmp->vm_ops && tmp->vm_ops->open)
tmp->vm_ops->open(tmp);
@@ -530,6 +540,22 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
out:
up_write(&mm->mmap_sem);
flush_tlb_mm(oldmm);
+
+ if (IS_ENABLED(CONFIG_SPECULATIVE_PAGE_FAULT)) {
+ /*
+ * Since the TLB has been flush, we can safely unmark the
+ * copied VMAs and allows the speculative page fault handler to
+ * process them again.
+ * Walk back the VMA list from the last marked VMA.
+ */
+ for (; last; last = last->vm_prev) {
+ if (last->vm_flags & VM_DONTCOPY)
+ continue;
+ if (!(last->vm_flags & VM_WIPEONFORK))
+ vm_write_end(last);
+ }
+ }
+
up_write(&oldmm->mmap_sem);
dup_userfaultfd_complete(&uf);
fail_uprobe_end:
--
2.20.1
^ permalink raw reply related [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-18 16:24 ` Laurent Dufour
@ 2019-01-19 17:05 ` zhong jiang
2019-01-19 17:05 ` zhong jiang
2019-01-22 16:22 ` zhong jiang
1 sibling, 1 reply; 46+ messages in thread
From: zhong jiang @ 2019-01-19 17:05 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/19 0:24, Laurent Dufour wrote:
> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>
>>>>> With the patch below, we don't hit the issue.
>>>>>
>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>
>>>>> It is observed that the following scenario results in
>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>> forever after few iterations.
>>>>>
>>>>> CPU 1 CPU 2 CPU 3
>>>>> Process 1, Process 1, Process 1,
>>>>> Thread A Thread B Thread C
>>>>>
>>>>> while (1) { while (1) { while(1) {
>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>> } }
>>>>>
>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>> on one of the CPUs at least. This can create a problem if one
>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>> entry can still modify old_page even after it is copied to
>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>> Nice catch and thanks for your investigation!
>>>>
>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>
>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> ---
>>>>> mm/memory.c | 7 +++++++
>>>>> 1 file changed, 7 insertions(+)
>>>>>
>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>> index 52080e4..1ea168ff 100644
>>>>> --- a/mm/memory.c
>>>>> +++ b/mm/memory.c
>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>> return VM_FAULT_RETRY;
>>>>> }
>>>>>
>>>>> + /*
>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>> + * in copy_one_pte
>>>>> + */
>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>> + flush_tlb_page(vmf.vma, address);
>>>>> +
>>>>> mem_cgroup_oom_enable();
>>>>> ret = handle_pte_fault(&vmf);
>>>>> mem_cgroup_oom_disable();
>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>
>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>
>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>
>>>
>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>
>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>> Hi, Vinayak and Laurent
>>
>> I think the below change will impact the performance significantly. Becuase most of process has many
>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>> call the flush_tlb_mm later.
>>
>> I think we can try the following way to do.
>>
>> vm_write_begin(vma)
>> copy_pte_range
>> vm_write_end(vma)
>>
>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>> Any thought?
>
> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>
> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>
> Vinayak, Zhong, could you please give it a try ?
>
Thanks, look good to me. I will try it.
Sincerely,
zhong jiang
> Thanks,
> Laurent.
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-19 17:05 ` zhong jiang
@ 2019-01-19 17:05 ` zhong jiang
0 siblings, 0 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-19 17:05 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/19 0:24, Laurent Dufour wrote:
> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>
>>>>> With the patch below, we don't hit the issue.
>>>>>
>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>
>>>>> It is observed that the following scenario results in
>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>> forever after few iterations.
>>>>>
>>>>> CPU 1 CPU 2 CPU 3
>>>>> Process 1, Process 1, Process 1,
>>>>> Thread A Thread B Thread C
>>>>>
>>>>> while (1) { while (1) { while(1) {
>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>> } }
>>>>>
>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>> on one of the CPUs at least. This can create a problem if one
>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>> entry can still modify old_page even after it is copied to
>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>> Nice catch and thanks for your investigation!
>>>>
>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>
>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> ---
>>>>> mm/memory.c | 7 +++++++
>>>>> 1 file changed, 7 insertions(+)
>>>>>
>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>> index 52080e4..1ea168ff 100644
>>>>> --- a/mm/memory.c
>>>>> +++ b/mm/memory.c
>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>> return VM_FAULT_RETRY;
>>>>> }
>>>>>
>>>>> + /*
>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>> + * in copy_one_pte
>>>>> + */
>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>> + flush_tlb_page(vmf.vma, address);
>>>>> +
>>>>> mem_cgroup_oom_enable();
>>>>> ret = handle_pte_fault(&vmf);
>>>>> mem_cgroup_oom_disable();
>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>
>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>
>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>
>>>
>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>
>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>> Hi, Vinayak and Laurent
>>
>> I think the below change will impact the performance significantly. Becuase most of process has many
>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>> call the flush_tlb_mm later.
>>
>> I think we can try the following way to do.
>>
>> vm_write_begin(vma)
>> copy_pte_range
>> vm_write_end(vma)
>>
>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>> Any thought?
>
> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>
> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>
> Vinayak, Zhong, could you please give it a try ?
>
Thanks, look good to me. I will try it.
Sincerely,
zhong jiang
> Thanks,
> Laurent.
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-18 16:24 ` Laurent Dufour
2019-01-19 17:05 ` zhong jiang
@ 2019-01-22 16:22 ` zhong jiang
2019-01-22 16:22 ` zhong jiang
2019-01-24 8:20 ` Laurent Dufour
1 sibling, 2 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-22 16:22 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/19 0:24, Laurent Dufour wrote:
> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>
>>>>> With the patch below, we don't hit the issue.
>>>>>
>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>
>>>>> It is observed that the following scenario results in
>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>> forever after few iterations.
>>>>>
>>>>> CPU 1 CPU 2 CPU 3
>>>>> Process 1, Process 1, Process 1,
>>>>> Thread A Thread B Thread C
>>>>>
>>>>> while (1) { while (1) { while(1) {
>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>> } }
>>>>>
>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>> on one of the CPUs at least. This can create a problem if one
>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>> entry can still modify old_page even after it is copied to
>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>> Nice catch and thanks for your investigation!
>>>>
>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>
>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> ---
>>>>> mm/memory.c | 7 +++++++
>>>>> 1 file changed, 7 insertions(+)
>>>>>
>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>> index 52080e4..1ea168ff 100644
>>>>> --- a/mm/memory.c
>>>>> +++ b/mm/memory.c
>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>> return VM_FAULT_RETRY;
>>>>> }
>>>>>
>>>>> + /*
>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>> + * in copy_one_pte
>>>>> + */
>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>> + flush_tlb_page(vmf.vma, address);
>>>>> +
>>>>> mem_cgroup_oom_enable();
>>>>> ret = handle_pte_fault(&vmf);
>>>>> mem_cgroup_oom_disable();
>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>
>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>
>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>
>>>
>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>
>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>> Hi, Vinayak and Laurent
>>
>> I think the below change will impact the performance significantly. Becuase most of process has many
>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>> call the flush_tlb_mm later.
>>
>> I think we can try the following way to do.
>>
>> vm_write_begin(vma)
>> copy_pte_range
>> vm_write_end(vma)
>>
>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>> Any thought?
>
> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>
> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>
> Vinayak, Zhong, could you please give it a try ?
>
Hi Laurent
I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
but It will better to filter the condition by is_cow_mapping. is it right?
for example:
if (is_cow_mapping(mnpt->vm_flags)) {
........
}
Thanks,
zhong jiang
> Thanks,
> Laurent.
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-22 16:22 ` zhong jiang
@ 2019-01-22 16:22 ` zhong jiang
2019-01-24 8:20 ` Laurent Dufour
1 sibling, 0 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-22 16:22 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/19 0:24, Laurent Dufour wrote:
> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>
>>>>> With the patch below, we don't hit the issue.
>>>>>
>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>
>>>>> It is observed that the following scenario results in
>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>> forever after few iterations.
>>>>>
>>>>> CPU 1 CPU 2 CPU 3
>>>>> Process 1, Process 1, Process 1,
>>>>> Thread A Thread B Thread C
>>>>>
>>>>> while (1) { while (1) { while(1) {
>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>> } }
>>>>>
>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>> on one of the CPUs at least. This can create a problem if one
>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>> entry can still modify old_page even after it is copied to
>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>> Nice catch and thanks for your investigation!
>>>>
>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>
>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>> ---
>>>>> mm/memory.c | 7 +++++++
>>>>> 1 file changed, 7 insertions(+)
>>>>>
>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>> index 52080e4..1ea168ff 100644
>>>>> --- a/mm/memory.c
>>>>> +++ b/mm/memory.c
>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>> return VM_FAULT_RETRY;
>>>>> }
>>>>>
>>>>> + /*
>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>> + * in copy_one_pte
>>>>> + */
>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>> + flush_tlb_page(vmf.vma, address);
>>>>> +
>>>>> mem_cgroup_oom_enable();
>>>>> ret = handle_pte_fault(&vmf);
>>>>> mem_cgroup_oom_disable();
>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>
>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>
>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>
>>>
>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>
>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>> Hi, Vinayak and Laurent
>>
>> I think the below change will impact the performance significantly. Becuase most of process has many
>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>> call the flush_tlb_mm later.
>>
>> I think we can try the following way to do.
>>
>> vm_write_begin(vma)
>> copy_pte_range
>> vm_write_end(vma)
>>
>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>> Any thought?
>
> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>
> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>
> Vinayak, Zhong, could you please give it a try ?
>
Hi Laurent
I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
but It will better to filter the condition by is_cow_mapping. is it right?
for example:
if (is_cow_mapping(mnpt->vm_flags)) {
........
}
Thanks,
zhong jiang
> Thanks,
> Laurent.
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-22 16:22 ` zhong jiang
2019-01-22 16:22 ` zhong jiang
@ 2019-01-24 8:20 ` Laurent Dufour
2019-01-25 12:32 ` zhong jiang
1 sibling, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2019-01-24 8:20 UTC (permalink / raw)
To: zhong jiang; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
Le 22/01/2019 à 17:22, zhong jiang a écrit :
> On 2019/1/19 0:24, Laurent Dufour wrote:
>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>> Hi Laurent,
>>>>>>>
>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>
>>>>>> With the patch below, we don't hit the issue.
>>>>>>
>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>
>>>>>> It is observed that the following scenario results in
>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>> forever after few iterations.
>>>>>>
>>>>>> CPU 1 CPU 2 CPU 3
>>>>>> Process 1, Process 1, Process 1,
>>>>>> Thread A Thread B Thread C
>>>>>>
>>>>>> while (1) { while (1) { while(1) {
>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>> } }
>>>>>>
>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>> entry can still modify old_page even after it is copied to
>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>> Nice catch and thanks for your investigation!
>>>>>
>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>
>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>> ---
>>>>>> mm/memory.c | 7 +++++++
>>>>>> 1 file changed, 7 insertions(+)
>>>>>>
>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>> index 52080e4..1ea168ff 100644
>>>>>> --- a/mm/memory.c
>>>>>> +++ b/mm/memory.c
>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>> return VM_FAULT_RETRY;
>>>>>> }
>>>>>>
>>>>>> + /*
>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>> + * in copy_one_pte
>>>>>> + */
>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>> +
>>>>>> mem_cgroup_oom_enable();
>>>>>> ret = handle_pte_fault(&vmf);
>>>>>> mem_cgroup_oom_disable();
>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>
>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>
>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>
>>>>
>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>
>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>> Hi, Vinayak and Laurent
>>>
>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>> call the flush_tlb_mm later.
>>>
>>> I think we can try the following way to do.
>>>
>>> vm_write_begin(vma)
>>> copy_pte_range
>>> vm_write_end(vma)
>>>
>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>> Any thought?
>>
>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>
>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>
>> Vinayak, Zhong, could you please give it a try ?
>>
> Hi Laurent
>
> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
Good news !
>
> but It will better to filter the condition by is_cow_mapping. is it right?
>
> for example:
>
> if (is_cow_mapping(mnpt->vm_flags)) {
>
> ........
> }
That's doable for sure but I don't think this has to be introduce in
dup_mmap().
Unless there is a real performance benefit to do so, I don't think
dup_mmap() has to mimic underlying checks done in copy_page_range().
Cheers,
Laurent.
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-24 8:20 ` Laurent Dufour
@ 2019-01-25 12:32 ` zhong jiang
2019-01-25 12:32 ` zhong jiang
2019-01-28 8:59 ` Laurent Dufour
0 siblings, 2 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-25 12:32 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/24 16:20, Laurent Dufour wrote:
> Le 22/01/2019 à 17:22, zhong jiang a écrit :
>> On 2019/1/19 0:24, Laurent Dufour wrote:
>>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>>> Hi Laurent,
>>>>>>>>
>>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>>
>>>>>>> With the patch below, we don't hit the issue.
>>>>>>>
>>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>>
>>>>>>> It is observed that the following scenario results in
>>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>>> forever after few iterations.
>>>>>>>
>>>>>>> CPU 1 CPU 2 CPU 3
>>>>>>> Process 1, Process 1, Process 1,
>>>>>>> Thread A Thread B Thread C
>>>>>>>
>>>>>>> while (1) { while (1) { while(1) {
>>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>>> } }
>>>>>>>
>>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>>> entry can still modify old_page even after it is copied to
>>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>>> Nice catch and thanks for your investigation!
>>>>>>
>>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>>
>>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>> ---
>>>>>>> mm/memory.c | 7 +++++++
>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>
>>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>>> index 52080e4..1ea168ff 100644
>>>>>>> --- a/mm/memory.c
>>>>>>> +++ b/mm/memory.c
>>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>>> return VM_FAULT_RETRY;
>>>>>>> }
>>>>>>>
>>>>>>> + /*
>>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>>> + * in copy_one_pte
>>>>>>> + */
>>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>>> +
>>>>>>> mem_cgroup_oom_enable();
>>>>>>> ret = handle_pte_fault(&vmf);
>>>>>>> mem_cgroup_oom_disable();
>>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>>
>>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>>
>>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>>
>>>>>
>>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>>
>>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>>> Hi, Vinayak and Laurent
>>>>
>>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>>> call the flush_tlb_mm later.
>>>>
>>>> I think we can try the following way to do.
>>>>
>>>> vm_write_begin(vma)
>>>> copy_pte_range
>>>> vm_write_end(vma)
>>>>
>>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>>> Any thought?
>>>
>>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>>
>>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>>
>>> Vinayak, Zhong, could you please give it a try ?
>>>
>> Hi Laurent
>>
>> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
>
> Good news !
>
>>
>> but It will better to filter the condition by is_cow_mapping. is it right?
>>
>> for example:
>>
>> if (is_cow_mapping(mnpt->vm_flags)) {
>> ........
>> }
>
> That's doable for sure but I don't think this has to be introduce in dup_mmap().
> Unless there is a real performance benefit to do so, I don't think dup_mmap() has to mimic underlying checks done in copy_page_range().
>
Hi, Laurent
I test the performace with microbench after appling the patch. I find
the page fault latency will increase about 8% than before. I think we
should use is_cow_mapping to waken the impact and I will try it out.
or we can use the following solution to replace as Vinayak has said.
if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
return VM_FAULT_RETRY;
Even though it will influence the performance of SPF, but at least it does
not bring in any negative impact. Any thought?
Thanks,
> Cheers,
> Laurent.
>
>
> .
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-25 12:32 ` zhong jiang
@ 2019-01-25 12:32 ` zhong jiang
2019-01-28 8:59 ` Laurent Dufour
1 sibling, 0 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-25 12:32 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/24 16:20, Laurent Dufour wrote:
> Le 22/01/2019 à 17:22, zhong jiang a écrit :
>> On 2019/1/19 0:24, Laurent Dufour wrote:
>>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>>> Hi Laurent,
>>>>>>>>
>>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>>
>>>>>>> With the patch below, we don't hit the issue.
>>>>>>>
>>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>>
>>>>>>> It is observed that the following scenario results in
>>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>>> forever after few iterations.
>>>>>>>
>>>>>>> CPU 1 CPU 2 CPU 3
>>>>>>> Process 1, Process 1, Process 1,
>>>>>>> Thread A Thread B Thread C
>>>>>>>
>>>>>>> while (1) { while (1) { while(1) {
>>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>>> } }
>>>>>>>
>>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>>> entry can still modify old_page even after it is copied to
>>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>>> Nice catch and thanks for your investigation!
>>>>>>
>>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>>
>>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>> ---
>>>>>>> mm/memory.c | 7 +++++++
>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>
>>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>>> index 52080e4..1ea168ff 100644
>>>>>>> --- a/mm/memory.c
>>>>>>> +++ b/mm/memory.c
>>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>>> return VM_FAULT_RETRY;
>>>>>>> }
>>>>>>>
>>>>>>> + /*
>>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>>> + * in copy_one_pte
>>>>>>> + */
>>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>>> +
>>>>>>> mem_cgroup_oom_enable();
>>>>>>> ret = handle_pte_fault(&vmf);
>>>>>>> mem_cgroup_oom_disable();
>>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>>
>>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>>
>>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>>
>>>>>
>>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>>
>>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>>> Hi, Vinayak and Laurent
>>>>
>>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>>> call the flush_tlb_mm later.
>>>>
>>>> I think we can try the following way to do.
>>>>
>>>> vm_write_begin(vma)
>>>> copy_pte_range
>>>> vm_write_end(vma)
>>>>
>>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>>> Any thought?
>>>
>>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>>
>>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>>
>>> Vinayak, Zhong, could you please give it a try ?
>>>
>> Hi Laurent
>>
>> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
>
> Good news !
>
>>
>> but It will better to filter the condition by is_cow_mapping. is it right?
>>
>> for example:
>>
>> if (is_cow_mapping(mnpt->vm_flags)) {
>> ........
>> }
>
> That's doable for sure but I don't think this has to be introduce in dup_mmap().
> Unless there is a real performance benefit to do so, I don't think dup_mmap() has to mimic underlying checks done in copy_page_range().
>
Hi, Laurent
I test the performace with microbench after appling the patch. I find
the page fault latency will increase about 8% than before. I think we
should use is_cow_mapping to waken the impact and I will try it out.
or we can use the following solution to replace as Vinayak has said.
if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
return VM_FAULT_RETRY;
Even though it will influence the performance of SPF, but at least it does
not bring in any negative impact. Any thought?
Thanks,
> Cheers,
> Laurent.
>
>
> .
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-25 12:32 ` zhong jiang
2019-01-25 12:32 ` zhong jiang
@ 2019-01-28 8:59 ` Laurent Dufour
2019-01-28 14:09 ` zhong jiang
1 sibling, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2019-01-28 8:59 UTC (permalink / raw)
To: zhong jiang; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
Le 25/01/2019 à 13:32, zhong jiang a écrit :
> On 2019/1/24 16:20, Laurent Dufour wrote:
>> Le 22/01/2019 à 17:22, zhong jiang a écrit :
>>> On 2019/1/19 0:24, Laurent Dufour wrote:
>>>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>>>> Hi Laurent,
>>>>>>>>>
>>>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>>>
>>>>>>>> With the patch below, we don't hit the issue.
>>>>>>>>
>>>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>>>
>>>>>>>> It is observed that the following scenario results in
>>>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>>>> forever after few iterations.
>>>>>>>>
>>>>>>>> CPU 1 CPU 2 CPU 3
>>>>>>>> Process 1, Process 1, Process 1,
>>>>>>>> Thread A Thread B Thread C
>>>>>>>>
>>>>>>>> while (1) { while (1) { while(1) {
>>>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>>>> } }
>>>>>>>>
>>>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>>>> entry can still modify old_page even after it is copied to
>>>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>>>> Nice catch and thanks for your investigation!
>>>>>>>
>>>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>>>
>>>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>> ---
>>>>>>>> mm/memory.c | 7 +++++++
>>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>>>> index 52080e4..1ea168ff 100644
>>>>>>>> --- a/mm/memory.c
>>>>>>>> +++ b/mm/memory.c
>>>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>>>> return VM_FAULT_RETRY;
>>>>>>>> }
>>>>>>>>
>>>>>>>> + /*
>>>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>>>> + * in copy_one_pte
>>>>>>>> + */
>>>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>>>> +
>>>>>>>> mem_cgroup_oom_enable();
>>>>>>>> ret = handle_pte_fault(&vmf);
>>>>>>>> mem_cgroup_oom_disable();
>>>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>>>
>>>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>>>
>>>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>>>
>>>>>>
>>>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>>>
>>>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>>>> Hi, Vinayak and Laurent
>>>>>
>>>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>>>> call the flush_tlb_mm later.
>>>>>
>>>>> I think we can try the following way to do.
>>>>>
>>>>> vm_write_begin(vma)
>>>>> copy_pte_range
>>>>> vm_write_end(vma)
>>>>>
>>>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>>>> Any thought?
>>>>
>>>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>>>
>>>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>>>
>>>> Vinayak, Zhong, could you please give it a try ?
>>>>
>>> Hi Laurent
>>>
>>> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
>>
>> Good news !
>>
>>>
>>> but It will better to filter the condition by is_cow_mapping. is it right?
>>>
>>> for example:
>>>
>>> if (is_cow_mapping(mnpt->vm_flags)) {
>>> ........
>>> }
>>
>> That's doable for sure but I don't think this has to be introduce in dup_mmap().
>> Unless there is a real performance benefit to do so, I don't think dup_mmap() has to mimic underlying checks done in copy_page_range().
>>
>
> Hi, Laurent
>
> I test the performace with microbench after appling the patch. I find
> the page fault latency will increase about 8% than before. I think we
> should use is_cow_mapping to waken the impact and I will try it out.
That's interesting, I would not expect such a higher latency assuming
that most of the area not in copied on write are also not managed by the
speculative page fault handler (file mapping, etc.). Anyway I'm looking
forward to see the result with additional is_cow_mapping() check.
> or we can use the following solution to replace as Vinayak has said.
>
> if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
> return VM_FAULT_RETRY;
>
> Even though it will influence the performance of SPF, but at least it does
> not bring in any negative impact. Any thought?
I don't agree, this checks will completely by pass the SPF handler for
all the COW areas, even if there is no race situation.
Cheers,
Laurent.
>
> Thanks,
>
>
>> Cheers,
>> Laurent.
>>
>>
>> .
>>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-28 8:59 ` Laurent Dufour
@ 2019-01-28 14:09 ` zhong jiang
2019-01-28 14:09 ` zhong jiang
2019-01-28 15:45 ` Laurent Dufour
0 siblings, 2 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-28 14:09 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/28 16:59, Laurent Dufour wrote:
> Le 25/01/2019 à 13:32, zhong jiang a écrit :
>> On 2019/1/24 16:20, Laurent Dufour wrote:
>>> Le 22/01/2019 à 17:22, zhong jiang a écrit :
>>>> On 2019/1/19 0:24, Laurent Dufour wrote:
>>>>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>>>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>>>>> Hi Laurent,
>>>>>>>>>>
>>>>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>>>>
>>>>>>>>> With the patch below, we don't hit the issue.
>>>>>>>>>
>>>>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>>>>
>>>>>>>>> It is observed that the following scenario results in
>>>>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>>>>> forever after few iterations.
>>>>>>>>>
>>>>>>>>> CPU 1 CPU 2 CPU 3
>>>>>>>>> Process 1, Process 1, Process 1,
>>>>>>>>> Thread A Thread B Thread C
>>>>>>>>>
>>>>>>>>> while (1) { while (1) { while(1) {
>>>>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>>>>> } }
>>>>>>>>>
>>>>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>>>>> entry can still modify old_page even after it is copied to
>>>>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>>>>> Nice catch and thanks for your investigation!
>>>>>>>>
>>>>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>>>>
>>>>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>> ---
>>>>>>>>> mm/memory.c | 7 +++++++
>>>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>>>
>>>>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>>>>> index 52080e4..1ea168ff 100644
>>>>>>>>> --- a/mm/memory.c
>>>>>>>>> +++ b/mm/memory.c
>>>>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>>>>> return VM_FAULT_RETRY;
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> + /*
>>>>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>>>>> + * in copy_one_pte
>>>>>>>>> + */
>>>>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>>>>> +
>>>>>>>>> mem_cgroup_oom_enable();
>>>>>>>>> ret = handle_pte_fault(&vmf);
>>>>>>>>> mem_cgroup_oom_disable();
>>>>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>>>>
>>>>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>>>>
>>>>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>>>>
>>>>>>>
>>>>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>>>>
>>>>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>>>>> Hi, Vinayak and Laurent
>>>>>>
>>>>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>>>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>>>>> call the flush_tlb_mm later.
>>>>>>
>>>>>> I think we can try the following way to do.
>>>>>>
>>>>>> vm_write_begin(vma)
>>>>>> copy_pte_range
>>>>>> vm_write_end(vma)
>>>>>>
>>>>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>>>>> Any thought?
>>>>>
>>>>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>>>>
>>>>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>>>>
>>>>> Vinayak, Zhong, could you please give it a try ?
>>>>>
>>>> Hi Laurent
>>>>
>>>> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
>>>
>>> Good news !
>>>
>>>>
>>>> but It will better to filter the condition by is_cow_mapping. is it right?
>>>>
>>>> for example:
>>>>
>>>> if (is_cow_mapping(mnpt->vm_flags)) {
>>>> ........
>>>> }
>>>
>>> That's doable for sure but I don't think this has to be introduce in dup_mmap().
>>> Unless there is a real performance benefit to do so, I don't think dup_mmap() has to mimic underlying checks done in copy_page_range().
>>>
>>
>> Hi, Laurent
>>
>> I test the performace with microbench after appling the patch. I find
>> the page fault latency will increase about 8% than before. I think we
>> should use is_cow_mapping to waken the impact and I will try it out.
>
> That's interesting, I would not expect such a higher latency assuming that most of the area not in copied on write are also not managed by the speculative page fault handler (file mapping, etc.). Anyway I'm looking forward to see the result with additional is_cow_mapping() check.
>
I test the performance again. It is the protect error access latency in lat_sig.c that it will result in a drop of 8% in that testcase.
The page fault latency, In fact, does not impact the performace. It seems to just the fluctuation.
Thanks,
zhong jiang
>> or we can use the following solution to replace as Vinayak has said.
>>
>> if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>> return VM_FAULT_RETRY;
>>
>> Even though it will influence the performance of SPF, but at least it does
>> not bring in any negative impact. Any thought?
>
> I don't agree, this checks will completely by pass the SPF handler for all the COW areas, even if there is no race situation.
>
> Cheers,
> Laurent.
>>
>> Thanks,
>>
>>
>>> Cheers,
>>> Laurent.
>>>
>>>
>>> .
>>>
>>
>>
>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-28 14:09 ` zhong jiang
@ 2019-01-28 14:09 ` zhong jiang
2019-01-28 15:45 ` Laurent Dufour
1 sibling, 0 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-28 14:09 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/28 16:59, Laurent Dufour wrote:
> Le 25/01/2019 à 13:32, zhong jiang a écrit :
>> On 2019/1/24 16:20, Laurent Dufour wrote:
>>> Le 22/01/2019 à 17:22, zhong jiang a écrit :
>>>> On 2019/1/19 0:24, Laurent Dufour wrote:
>>>>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>>>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>>>>> Hi Laurent,
>>>>>>>>>>
>>>>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>>>>
>>>>>>>>> With the patch below, we don't hit the issue.
>>>>>>>>>
>>>>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>>>>
>>>>>>>>> It is observed that the following scenario results in
>>>>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>>>>> forever after few iterations.
>>>>>>>>>
>>>>>>>>> CPU 1 CPU 2 CPU 3
>>>>>>>>> Process 1, Process 1, Process 1,
>>>>>>>>> Thread A Thread B Thread C
>>>>>>>>>
>>>>>>>>> while (1) { while (1) { while(1) {
>>>>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>>>>> } }
>>>>>>>>>
>>>>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>>>>> entry can still modify old_page even after it is copied to
>>>>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>>>>> Nice catch and thanks for your investigation!
>>>>>>>>
>>>>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>>>>
>>>>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>> ---
>>>>>>>>> mm/memory.c | 7 +++++++
>>>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>>>
>>>>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>>>>> index 52080e4..1ea168ff 100644
>>>>>>>>> --- a/mm/memory.c
>>>>>>>>> +++ b/mm/memory.c
>>>>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>>>>> return VM_FAULT_RETRY;
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> + /*
>>>>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>>>>> + * in copy_one_pte
>>>>>>>>> + */
>>>>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>>>>> +
>>>>>>>>> mem_cgroup_oom_enable();
>>>>>>>>> ret = handle_pte_fault(&vmf);
>>>>>>>>> mem_cgroup_oom_disable();
>>>>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>>>>
>>>>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>>>>
>>>>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>>>>
>>>>>>>
>>>>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>>>>
>>>>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>>>>> Hi, Vinayak and Laurent
>>>>>>
>>>>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>>>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>>>>> call the flush_tlb_mm later.
>>>>>>
>>>>>> I think we can try the following way to do.
>>>>>>
>>>>>> vm_write_begin(vma)
>>>>>> copy_pte_range
>>>>>> vm_write_end(vma)
>>>>>>
>>>>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>>>>> Any thought?
>>>>>
>>>>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>>>>
>>>>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>>>>
>>>>> Vinayak, Zhong, could you please give it a try ?
>>>>>
>>>> Hi Laurent
>>>>
>>>> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
>>>
>>> Good news !
>>>
>>>>
>>>> but It will better to filter the condition by is_cow_mapping. is it right?
>>>>
>>>> for example:
>>>>
>>>> if (is_cow_mapping(mnpt->vm_flags)) {
>>>> ........
>>>> }
>>>
>>> That's doable for sure but I don't think this has to be introduce in dup_mmap().
>>> Unless there is a real performance benefit to do so, I don't think dup_mmap() has to mimic underlying checks done in copy_page_range().
>>>
>>
>> Hi, Laurent
>>
>> I test the performace with microbench after appling the patch. I find
>> the page fault latency will increase about 8% than before. I think we
>> should use is_cow_mapping to waken the impact and I will try it out.
>
> That's interesting, I would not expect such a higher latency assuming that most of the area not in copied on write are also not managed by the speculative page fault handler (file mapping, etc.). Anyway I'm looking forward to see the result with additional is_cow_mapping() check.
>
I test the performance again. It is the protect error access latency in lat_sig.c that it will result in a drop of 8% in that testcase.
The page fault latency, In fact, does not impact the performace. It seems to just the fluctuation.
Thanks,
zhong jiang
>> or we can use the following solution to replace as Vinayak has said.
>>
>> if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>> return VM_FAULT_RETRY;
>>
>> Even though it will influence the performance of SPF, but at least it does
>> not bring in any negative impact. Any thought?
>
> I don't agree, this checks will completely by pass the SPF handler for all the COW areas, even if there is no race situation.
>
> Cheers,
> Laurent.
>>
>> Thanks,
>>
>>
>>> Cheers,
>>> Laurent.
>>>
>>>
>>> .
>>>
>>
>>
>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-28 14:09 ` zhong jiang
2019-01-28 14:09 ` zhong jiang
@ 2019-01-28 15:45 ` Laurent Dufour
2019-01-29 15:40 ` zhong jiang
1 sibling, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2019-01-28 15:45 UTC (permalink / raw)
To: zhong jiang; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
Le 28/01/2019 à 15:09, zhong jiang a écrit :
> On 2019/1/28 16:59, Laurent Dufour wrote:
>> Le 25/01/2019 à 13:32, zhong jiang a écrit :
>>> On 2019/1/24 16:20, Laurent Dufour wrote:
>>>> Le 22/01/2019 à 17:22, zhong jiang a écrit :
>>>>> On 2019/1/19 0:24, Laurent Dufour wrote:
>>>>>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>>>>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>>>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>>>>>> Hi Laurent,
>>>>>>>>>>>
>>>>>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>>>>>
>>>>>>>>>> With the patch below, we don't hit the issue.
>>>>>>>>>>
>>>>>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>>>>>
>>>>>>>>>> It is observed that the following scenario results in
>>>>>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>>>>>> forever after few iterations.
>>>>>>>>>>
>>>>>>>>>> CPU 1 CPU 2 CPU 3
>>>>>>>>>> Process 1, Process 1, Process 1,
>>>>>>>>>> Thread A Thread B Thread C
>>>>>>>>>>
>>>>>>>>>> while (1) { while (1) { while(1) {
>>>>>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>>>>>> } }
>>>>>>>>>>
>>>>>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>>>>>> entry can still modify old_page even after it is copied to
>>>>>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>>>>>> Nice catch and thanks for your investigation!
>>>>>>>>>
>>>>>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>>>>>
>>>>>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>>> ---
>>>>>>>>>> mm/memory.c | 7 +++++++
>>>>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>>>>
>>>>>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>>>>>> index 52080e4..1ea168ff 100644
>>>>>>>>>> --- a/mm/memory.c
>>>>>>>>>> +++ b/mm/memory.c
>>>>>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>>>>>> return VM_FAULT_RETRY;
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> + /*
>>>>>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>>>>>> + * in copy_one_pte
>>>>>>>>>> + */
>>>>>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>>>>>> +
>>>>>>>>>> mem_cgroup_oom_enable();
>>>>>>>>>> ret = handle_pte_fault(&vmf);
>>>>>>>>>> mem_cgroup_oom_disable();
>>>>>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>>>>>
>>>>>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>>>>>
>>>>>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>>>>>
>>>>>>>>
>>>>>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>>>>>
>>>>>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>>>>>> Hi, Vinayak and Laurent
>>>>>>>
>>>>>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>>>>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>>>>>> call the flush_tlb_mm later.
>>>>>>>
>>>>>>> I think we can try the following way to do.
>>>>>>>
>>>>>>> vm_write_begin(vma)
>>>>>>> copy_pte_range
>>>>>>> vm_write_end(vma)
>>>>>>>
>>>>>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>>>>>> Any thought?
>>>>>>
>>>>>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>>>>>
>>>>>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>>>>>
>>>>>> Vinayak, Zhong, could you please give it a try ?
>>>>>>
>>>>> Hi Laurent
>>>>>
>>>>> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
>>>>
>>>> Good news !
>>>>
>>>>>
>>>>> but It will better to filter the condition by is_cow_mapping. is it right?
>>>>>
>>>>> for example:
>>>>>
>>>>> if (is_cow_mapping(mnpt->vm_flags)) {
>>>>> ........
>>>>> }
>>>>
>>>> That's doable for sure but I don't think this has to be introduce in dup_mmap().
>>>> Unless there is a real performance benefit to do so, I don't think dup_mmap() has to mimic underlying checks done in copy_page_range().
>>>>
>>>
>>> Hi, Laurent
>>>
>>> I test the performace with microbench after appling the patch. I find
>>> the page fault latency will increase about 8% than before. I think we
>>> should use is_cow_mapping to waken the impact and I will try it out.
>>
>> That's interesting, I would not expect such a higher latency assuming that most of the area not in copied on write are also not managed by the speculative page fault handler (file mapping, etc.). Anyway I'm looking forward to see the result with additional is_cow_mapping() check.
>>
> I test the performance again. It is the protect error access latency in lat_sig.c that it will result in a drop of 8% in that testcase.
What is that "protect error access latency in lat_sig.c" ?
> The page fault latency, In fact, does not impact the performace. It seems to just the fluctuation.
>
> Thanks,
> zhong jiang
>>> or we can use the following solution to replace as Vinayak has said.
>>>
>>> if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>> return VM_FAULT_RETRY;
>>>
>>> Even though it will influence the performance of SPF, but at least it does
>>> not bring in any negative impact. Any thought?
>>
>> I don't agree, this checks will completely by pass the SPF handler for all the COW areas, even if there is no race situation.
>>
>> Cheers,
>> Laurent.
>>>
>>> Thanks,
>>>
>>>
>>>> Cheers,
>>>> Laurent.
>>>>
>>>>
>>>> .
>>>>
>>>
>>>
>>
>>
>>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2019-01-28 15:45 ` Laurent Dufour
@ 2019-01-29 15:40 ` zhong jiang
0 siblings, 0 replies; 46+ messages in thread
From: zhong jiang @ 2019-01-29 15:40 UTC (permalink / raw)
To: Laurent Dufour; +Cc: Vinayak Menon, Linux-MM, charante, Ganesh Mahendran
On 2019/1/28 23:45, Laurent Dufour wrote:
> Le 28/01/2019 à 15:09, zhong jiang a écrit :
>> On 2019/1/28 16:59, Laurent Dufour wrote:
>>> Le 25/01/2019 à 13:32, zhong jiang a écrit :
>>>> On 2019/1/24 16:20, Laurent Dufour wrote:
>>>>> Le 22/01/2019 à 17:22, zhong jiang a écrit :
>>>>>> On 2019/1/19 0:24, Laurent Dufour wrote:
>>>>>>> Le 17/01/2019 à 16:51, zhong jiang a écrit :
>>>>>>>> On 2019/1/16 19:41, Vinayak Menon wrote:
>>>>>>>>> On 1/15/2019 1:54 PM, Laurent Dufour wrote:
>>>>>>>>>> Le 14/01/2019 à 14:19, Vinayak Menon a écrit :
>>>>>>>>>>> On 1/11/2019 9:13 PM, Vinayak Menon wrote:
>>>>>>>>>>>> Hi Laurent,
>>>>>>>>>>>>
>>>>>>>>>>>> We are observing an issue with speculative page fault with the following test code on ARM64 (4.14 kernel, 8 cores).
>>>>>>>>>>>
>>>>>>>>>>> With the patch below, we don't hit the issue.
>>>>>>>>>>>
>>>>>>>>>>> From: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>>>> Date: Mon, 14 Jan 2019 16:06:34 +0530
>>>>>>>>>>> Subject: [PATCH] mm: flush stale tlb entries on speculative write fault
>>>>>>>>>>>
>>>>>>>>>>> It is observed that the following scenario results in
>>>>>>>>>>> threads A and B of process 1 blocking on pthread_mutex_lock
>>>>>>>>>>> forever after few iterations.
>>>>>>>>>>>
>>>>>>>>>>> CPU 1 CPU 2 CPU 3
>>>>>>>>>>> Process 1, Process 1, Process 1,
>>>>>>>>>>> Thread A Thread B Thread C
>>>>>>>>>>>
>>>>>>>>>>> while (1) { while (1) { while(1) {
>>>>>>>>>>> pthread_mutex_lock(l) pthread_mutex_lock(l) fork
>>>>>>>>>>> pthread_mutex_unlock(l) pthread_mutex_unlock(l) }
>>>>>>>>>>> } }
>>>>>>>>>>>
>>>>>>>>>>> When from thread C, copy_one_pte write-protects the parent pte
>>>>>>>>>>> (of lock l), stale tlb entries can exist with write permissions
>>>>>>>>>>> on one of the CPUs at least. This can create a problem if one
>>>>>>>>>>> of the threads A or B hits the write fault. Though dup_mmap calls
>>>>>>>>>>> flush_tlb_mm after copy_page_range, since speculative page fault
>>>>>>>>>>> does not take mmap_sem it can proceed further fixing a fault soon
>>>>>>>>>>> after CPU 3 does ptep_set_wrprotect. But the CPU with stale tlb
>>>>>>>>>>> entry can still modify old_page even after it is copied to
>>>>>>>>>>> new_page by wp_page_copy, thus causing a corruption.
>>>>>>>>>> Nice catch and thanks for your investigation!
>>>>>>>>>>
>>>>>>>>>> There is a real synchronization issue here between copy_page_range() and the speculative page fault handler. I didn't get it on PowerVM since the TLB are flushed when arch_exit_lazy_mode() is called in copy_page_range() but now, I can get it when running on x86_64.
>>>>>>>>>>
>>>>>>>>>>> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
>>>>>>>>>>> ---
>>>>>>>>>>> mm/memory.c | 7 +++++++
>>>>>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>>>>>
>>>>>>>>>>> diff --git a/mm/memory.c b/mm/memory.c
>>>>>>>>>>> index 52080e4..1ea168ff 100644
>>>>>>>>>>> --- a/mm/memory.c
>>>>>>>>>>> +++ b/mm/memory.c
>>>>>>>>>>> @@ -4507,6 +4507,13 @@ int __handle_speculative_fault(struct mm_struct *mm, unsigned long address,
>>>>>>>>>>> return VM_FAULT_RETRY;
>>>>>>>>>>> }
>>>>>>>>>>>
>>>>>>>>>>> + /*
>>>>>>>>>>> + * Discard tlb entries created before ptep_set_wrprotect
>>>>>>>>>>> + * in copy_one_pte
>>>>>>>>>>> + */
>>>>>>>>>>> + if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>>>>>>>>> + flush_tlb_page(vmf.vma, address);
>>>>>>>>>>> +
>>>>>>>>>>> mem_cgroup_oom_enable();
>>>>>>>>>>> ret = handle_pte_fault(&vmf);
>>>>>>>>>>> mem_cgroup_oom_disable();
>>>>>>>>>> Your patch is fixing the race but I'm wondering about the cost of these tlb flushes. Here we are flushing on a per page basis (architecture like x86_64 are smarter and flush more pages) but there is a request to flush a range of tlb entries each time a cow page is newly touched. I think there could be some bad impact here.
>>>>>>>>>>
>>>>>>>>>> Another option would be to flush the range in copy_pte_range() before unlocking the page table lock. This will flush entries flush_tlb_mm() would later handle in dup_mmap() but that will be called once per fork per cow VMA.
>>>>>>>>>
>>>>>>>>> But wouldn't this cause an unnecessary impact if most of the COW pages remain untouched (which I assume would be the usual case) and thus do not create a fault ?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> I tried the attached patch which seems to fix the issue on x86_64. Could you please give it a try on arm64 ?
>>>>>>>>>>
>>>>>>>>> Your patch works fine on arm64 with a minor change. Thanks Laurent.
>>>>>>>> Hi, Vinayak and Laurent
>>>>>>>>
>>>>>>>> I think the below change will impact the performance significantly. Becuase most of process has many
>>>>>>>> vmas with cow flags. Flush the tlb in advance is not the better way to avoid the issue and it will
>>>>>>>> call the flush_tlb_mm later.
>>>>>>>>
>>>>>>>> I think we can try the following way to do.
>>>>>>>>
>>>>>>>> vm_write_begin(vma)
>>>>>>>> copy_pte_range
>>>>>>>> vm_write_end(vma)
>>>>>>>>
>>>>>>>> The speculative page fault will return to grap the mmap_sem to run the nromal path.
>>>>>>>> Any thought?
>>>>>>>
>>>>>>> Here is a new version of the patch fixing this issue. There is no additional TLB flush, all the fix is belonging on vm_write_{begin,end} calls.
>>>>>>>
>>>>>>> I did some test on x86_64 and PowerPC but that needs to be double check on arm64.
>>>>>>>
>>>>>>> Vinayak, Zhong, could you please give it a try ?
>>>>>>>
>>>>>> Hi Laurent
>>>>>>
>>>>>> I apply the patch you had attached and none of any abnormal thing came in two days. It is feasible to fix the issue.
>>>>>
>>>>> Good news !
>>>>>
>>>>>>
>>>>>> but It will better to filter the condition by is_cow_mapping. is it right?
>>>>>>
>>>>>> for example:
>>>>>>
>>>>>> if (is_cow_mapping(mnpt->vm_flags)) {
>>>>>> ........
>>>>>> }
>>>>>
>>>>> That's doable for sure but I don't think this has to be introduce in dup_mmap().
>>>>> Unless there is a real performance benefit to do so, I don't think dup_mmap() has to mimic underlying checks done in copy_page_range().
>>>>>
>>>>
>>>> Hi, Laurent
>>>>
>>>> I test the performace with microbench after appling the patch. I find
>>>> the page fault latency will increase about 8% than before. I think we
>>>> should use is_cow_mapping to waken the impact and I will try it out.
>>>
>>> That's interesting, I would not expect such a higher latency assuming that most of the area not in copied on write are also not managed by the speculative page fault handler (file mapping, etc.). Anyway I'm looking forward to see the result with additional is_cow_mapping() check.
>>>
>> I test the performance again. It is the protect error access latency in lat_sig.c that it will result in a drop of 8% in that testcase.
>
> What is that "protect error access latency in lat_sig.c" ?
>
It is the protect error access that the source code is lat_sig.c in microbench.
>> The page fault latency, In fact, does not impact the performace. It seems to just the fluctuation.
>>
>> Thanks,
>> zhong jiang
>>>> or we can use the following solution to replace as Vinayak has said.
>>>>
>>>> if (flags & FAULT_FLAG_WRITE && !pte_write(vmf.orig_pte))
>>>> return VM_FAULT_RETRY;
>>>>
>>>> Even though it will influence the performance of SPF, but at least it does
>>>> not bring in any negative impact. Any thought?
>>>
>>> I don't agree, this checks will completely by pass the SPF handler for all the COW areas, even if there is no race situation.
>>>
>>> Cheers,
>>> Laurent.
>>>>
>>>> Thanks,
>>>>
>>>>
>>>>> Cheers,
>>>>> Laurent.
>>>>>
>>>>>
>>>>> .
>>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>
>
> .
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-11-05 10:42 ` Balbir Singh
@ 2018-11-05 16:08 ` Laurent Dufour
0 siblings, 0 replies; 46+ messages in thread
From: Laurent Dufour @ 2018-11-05 16:08 UTC (permalink / raw)
To: Balbir Singh, Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
kemi.wang, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, paulmck,
Tim Chen, linuxppc-dev, x86
Le 05/11/2018 A 11:42, Balbir Singh a A(C)critA :
> On Thu, May 17, 2018 at 01:06:07PM +0200, Laurent Dufour wrote:
>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>> page fault without holding the mm semaphore [1].
>>
>> The idea is to try to handle user space page faults without holding the
>> mmap_sem. This should allow better concurrency for massively threaded
>
> Question -- I presume mmap_sem (rw_semaphore implementation tested against)
> was qrwlock?
I don't think so, this series doesn't change the mmap_sem definition so
it still belongs to the 'struct rw_semaphore'.
Laurent.
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-05-17 11:06 Laurent Dufour
2018-05-28 5:23 ` Song, HaiyanX
@ 2018-11-05 10:42 ` Balbir Singh
2018-11-05 16:08 ` Laurent Dufour
1 sibling, 1 reply; 46+ messages in thread
From: Balbir Singh @ 2018-11-05 10:42 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
kemi.wang, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, paulmck,
Tim Chen, linuxppc-dev, x86
On Thu, May 17, 2018 at 01:06:07PM +0200, Laurent Dufour wrote:
> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
> page fault without holding the mm semaphore [1].
>
> The idea is to try to handle user space page faults without holding the
> mmap_sem. This should allow better concurrency for massively threaded
Question -- I presume mmap_sem (rw_semaphore implementation tested against)
was qrwlock?
Balbir Singh.
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-08-22 14:23 ` Laurent Dufour
@ 2018-09-18 6:42 ` Song, HaiyanX
0 siblings, 0 replies; 46+ messages in thread
From: Song, HaiyanX @ 2018-09-18 6:42 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
[-- Attachment #1: Type: text/plain, Size: 46630 bytes --]
Hi Laurent,
I am sorry for replying you so late.
The previous LKP test for this case are running on the same Intel skylake 4s platform, but it need maintain recently.
So I changed to another test box to run the page_fault3 test case, it is Intel skylake 2s platform (nr_cpu: 104, memory: 64G).
I applied your patch to the SPF kernel (commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12), then triggered below 2 cases test.
a) Turn on the SPF handler by below command, then run page_fault3-thp-always test.
echo 1 > /proc/sys/vm/speculative_page_fault
b) Turn off the SPF handler by below command, then run page_fault3-thp-always test.
echo 0 > /proc/sys/vm/speculative_page_fault
Every test run 3 times, and then get test result and capture perf data.
Here is average result for will-it-scale.per_thread_ops:
SPF_turn_off SPF_turn_on
page_fault3-THP-Alwasys.will-it-scale.per_thread_ops 31963 26285
Best regards,
Haiyan Song
________________________________________
From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
Sent: Wednesday, August 22, 2018 10:23 PM
To: Song, HaiyanX
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: Re: [PATCH v11 00/26] Speculative page faults
On 03/08/2018 08:36, Song, HaiyanX wrote:
> Hi Laurent,
Hi Haiyan,
Sorry for the late answer, I was off a couple of days.
>
> Thanks for your analysis for the last perf results.
> Your mentioned ," the major differences at the head of the perf report is the 92% testcase which is weirdly not reported
> on the head side", which is a bug of 0-day,and it caused the item is not counted in perf.
>
> I've triggered the test page_fault2 and page_fault3 again only with thread mode of will-it-scale on 0-day (on the same test box,every case tested 3 times).
> I checked the perf report have no above mentioned problem.
>
> I have compared them, found some items have difference, such as below case:
> page_fault2-thp-always: handle_mm_fault, base: 45.22% head: 29.41%
> page_fault3-thp-always: handle_mm_fault, base: 22.95% head: 14.15%
These would mean that the system spends lees time running handle_mm_fault()
when SPF is in the picture in this 2 cases which is good. This should lead to
better results with the SPF series, and I can't find any values higher on the
head side.
>
> So i attached the perf result in mail again, could your have a look again for checking the difference between base and head commit.
I took a close look to all the perf result you sent, but I can't identify any
major difference. But the compiler optimization is getting rid of the
handle_pte_fault() symbol on the base kernel which add complexity to check the
differences.
To get rid of that, I'm proposing that you applied the attached patch to the
spf kernel. This patch is allowing to turn on/off the SPF handler through
/proc/sys/vm/speculative_page_fault.
This should ease the testing by limiting the reboot and avoid kernel's symbols
mismatch. Obviously there is still a small overhead due to the check but it
should not be viewable.
With this patch applied you can simply run
echo 1 > /proc/sys/vm/speculative_page_fault
to run a test with the speculative page fault handler activated. Or run
echo 0 > /proc/sys/vm/speculative_page_fault
to run a test without it.
I'm really sorry to asking that again, but could please run the test
page_fault3_base_THP-Always with and without SPF and capture the perf output.
I think we should focus on that test which showed the biggest regression.
Thanks,
Laurent.
>
> Thanks,
> Haiyan, Song
>
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Tuesday, July 17, 2018 5:36 PM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> On 13/07/2018 05:56, Song, HaiyanX wrote:
>> Hi Laurent,
>
> Hi Haiyan,
>
> Thanks a lot for sharing this perf reports.
>
> I looked at them closely, and I've to admit that I was not able to found a
> major difference between the base and the head report, except that
> handle_pte_fault() is no more in-lined in the head one.
>
> As expected, __handle_speculative_fault() is never traced since these tests are
> dealing with file mapping, not handled in the speculative way.
>
> When running these test did you seen a major differences in the test's result
> between base and head ?
>
> From the number of cycles counted, the biggest difference is page_fault3 when
> run with the THP enabled:
> BASE HEAD Delta
> page_fault2_base_thp_never 1142252426747 1065866197589 -6.69%
> page_fault2_base_THP-Alwasys 1124844374523 1076312228927 -4.31%
> page_fault3_base_thp_never 1099387298152 1134118402345 3.16%
> page_fault3_base_THP-Always 1059370178101 853985561949 -19.39%
>
>
> The very weird thing is the difference of the delta cycles reported between
> thp never and thp always, because the speculative way is aborted when checking
> for the vma->ops field, which is the same in both case, and the thp is never
> checked. So there is no code covering differnce, on the speculative path,
> between these 2 cases. This leads me to think that there are other interactions
> interfering in the measure.
>
> Looking at the perf-profile_page_fault3_*_THP-Always, the major differences at
> the head of the perf report is the 92% testcase which is weirdly not reported
> on the head side :
> 92.02% 22.33% page_fault3_processes [.] testcase
> 92.02% testcase
>
> Then the base reported 37.67% for __do_page_fault() where the head reported
> 48.41%, but the only difference in this function, between base and head, is the
> call to handle_speculative_fault(). But this is a macro checking for the fault
> flags, and mm->users and then calling __handle_speculative_fault() if needed.
> So this can't explain this difference, except if __handle_speculative_fault()
> is inlined in __do_page_fault().
> Is this the case on your build ?
>
> Haiyan, do you still have the output of the test to check those numbers too ?
>
> Cheers,
> Laurent
>
>> I attached the perf-profile.gz file for case page_fault2 and page_fault3. These files were captured during test the related test case.
>> Please help to check on these data if it can help you to find the higher change. Thanks.
>>
>> File name perf-profile_page_fault2_head_THP-Always.gz, means the perf-profile result get from page_fault2
>> tested for head commit (a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12) with THP_always configuration.
>>
>> Best regards,
>> Haiyan Song
>>
>> ________________________________________
>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>> Sent: Thursday, July 12, 2018 1:05 AM
>> To: Song, HaiyanX
>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>
>> Hi Haiyan,
>>
>> Do you get a chance to capture some performance cycles on your system ?
>> I still can't get these numbers on my hardware.
>>
>> Thanks,
>> Laurent.
>>
>> On 04/07/2018 09:51, Laurent Dufour wrote:
>>> On 04/07/2018 05:23, Song, HaiyanX wrote:
>>>> Hi Laurent,
>>>>
>>>>
>>>> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
>>>> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
>>>
>>> Repeating the test only 3 times seems a bit too low to me.
>>>
>>> I'll focus on the higher change for the moment, but I don't have access to such
>>> a hardware.
>>>
>>> Is possible to provide a diff between base and SPF of the performance cycles
>>> measured when running page_fault3 and page_fault2 when the 20% change is detected.
>>>
>>> Please stay focus on the test case process to see exactly where the series is
>>> impacting.
>>>
>>> Thanks,
>>> Laurent.
>>>
>>>>
>>>> And I did not find other high variation on test case result.
>>>>
>>>> a). Enable THP
>>>> testcase base stddev change head stddev metric
>>>> page_fault3/enable THP 10519 ± 3% -20.5% 8368 ±6% will-it-scale.per_thread_ops
>>>> page_fault2/enalbe THP 8281 ± 2% -18.8% 6728 will-it-scale.per_thread_ops
>>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>>
>>>> b). Disable THP
>>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>>
>>>>
>>>> Best regards,
>>>> Haiyan Song
>>>> ________________________________________
>>>> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Monday, July 02, 2018 4:59 PM
>>>> To: Song, HaiyanX
>>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> On 11/06/2018 09:49, Song, HaiyanX wrote:
>>>>> Hi Laurent,
>>>>>
>>>>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>>>>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>>>>> V9 patch serials.
>>>>>
>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>>>>> commit id:
>>>>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>>>>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>>>>> Benchmark: will-it-scale
>>>>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>>>>
>>>>> Metrics:
>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>> THP: enable / disable
>>>>> nr_task:100%
>>>>>
>>>>> 1. Regressions:
>>>>>
>>>>> a). Enable THP
>>>>> testcase base change head metric
>>>>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>>>>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>>>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>>>
>>>>> b). Disable THP
>>>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>>>
>>>>> Notes: for the above values of test result, the higher is better.
>>>>
>>>> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
>>>> get reproducible results. The results have huge variation, even on the vanilla
>>>> kernel, and I can't state on any changes due to that.
>>>>
>>>> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
>>>> measure any changes between the vanilla and the SPF patched ones:
>>>>
>>>> test THP enabled 4.17.0-rc4-mm1 spf delta
>>>> page_fault3_threads 2697.7 2683.5 -0.53%
>>>> page_fault2_threads 170660.6 169574.1 -0.64%
>>>> context_switch1_threads 6915269.2 6877507.3 -0.55%
>>>> context_switch1_processes 6478076.2 6529493.5 0.79%
>>>> brk1 243391.2 238527.5 -2.00%
>>>>
>>>> Tests were run 10 times, no high variation detected.
>>>>
>>>> Did you see high variation on your side ? How many times the test were run to
>>>> compute the average values ?
>>>>
>>>> Thanks,
>>>> Laurent.
>>>>
>>>>
>>>>>
>>>>> 2. Improvement: not found improvement based on the selected test cases.
>>>>>
>>>>>
>>>>> Best regards
>>>>> Haiyan Song
>>>>> ________________________________________
>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>> Sent: Monday, May 28, 2018 4:54 PM
>>>>> To: Song, HaiyanX
>>>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>>>
>>>>> On 28/05/2018 10:22, Haiyan Song wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> Yes, these tests are done on V9 patch.
>>>>>
>>>>> Do you plan to give this V11 a run ?
>>>>>
>>>>>>
>>>>>>
>>>>>> Best regards,
>>>>>> Haiyan Song
>>>>>>
>>>>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>>>>
>>>>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>>>>> tested on Intel 4s Skylake platform.
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>>>>> series" while responding to the v11 header series...
>>>>>>> Were these tests done on v9 or v11 ?
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Laurent.
>>>>>>>
>>>>>>>>
>>>>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>>>>> Commit id:
>>>>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>>>>> Benchmark suite: will-it-scale
>>>>>>>> Download link:
>>>>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>>>>> Metrics:
>>>>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>>>>> THP: enable / disable
>>>>>>>> nr_task: 100%
>>>>>>>>
>>>>>>>> 1. Regressions:
>>>>>>>> a) THP enabled:
>>>>>>>> testcase base change head metric
>>>>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>>>>
>>>>>>>> b) THP disabled:
>>>>>>>> testcase base change head metric
>>>>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>>>>
>>>>>>>> 2. Improvements:
>>>>>>>> a) THP enabled:
>>>>>>>> testcase base change head metric
>>>>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>>>>
>>>>>>>> b) THP disabled:
>>>>>>>> testcase base change head metric
>>>>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>>>>
>>>>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>>>>
>>>>>>>>
>>>>>>>> Best regards
>>>>>>>> Haiyan Song
>>>>>>>>
>>>>>>>> ________________________________________
>>>>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>>>>
>>>>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>>>>> page fault without holding the mm semaphore [1].
>>>>>>>>
>>>>>>>> The idea is to try to handle user space page faults without holding the
>>>>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>>>>> process since the page fault handler will not wait for other threads memory
>>>>>>>> layout change to be done, assuming that this change is done in another part
>>>>>>>> of the process's memory space. This type page fault is named speculative
>>>>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>>>>> is failing its processing and a classic page fault is then tried.
>>>>>>>>
>>>>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>>>>> limiting the locking contention to these operations which are expected to
>>>>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>>>>> benchmark anymore.
>>>>>>>>
>>>>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>>>>> have to be protected against parallel changes. This is done by using a per
>>>>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>>>>> speculative page fault in that case.
>>>>>>>>
>>>>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>>>>> checked during the page fault are modified.
>>>>>>>>
>>>>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>>>>> parallel change is possible at this time.
>>>>>>>>
>>>>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>>>>> classic page fault handler will be called to handle the operation while
>>>>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>>>>> PTE.
>>>>>>>>
>>>>>>>> In pseudo code, this could be seen as:
>>>>>>>> speculative_page_fault()
>>>>>>>> {
>>>>>>>> vma = get_vma()
>>>>>>>> check vma sequence count
>>>>>>>> check vma's support
>>>>>>>> disable interrupt
>>>>>>>> check pgd,p4d,...,pte
>>>>>>>> save pmd and pte in vmf
>>>>>>>> save vma sequence counter in vmf
>>>>>>>> enable interrupt
>>>>>>>> check vma sequence count
>>>>>>>> handle_pte_fault(vma)
>>>>>>>> ..
>>>>>>>> page = alloc_page()
>>>>>>>> pte_map_lock()
>>>>>>>> disable interrupt
>>>>>>>> abort if sequence counter has changed
>>>>>>>> abort if pmd or pte has changed
>>>>>>>> pte map and lock
>>>>>>>> enable interrupt
>>>>>>>> if abort
>>>>>>>> free page
>>>>>>>> abort
>>>>>>>> ...
>>>>>>>> }
>>>>>>>>
>>>>>>>> arch_fault_handler()
>>>>>>>> {
>>>>>>>> if (speculative_page_fault(&vma))
>>>>>>>> goto done
>>>>>>>> again:
>>>>>>>> lock(mmap_sem)
>>>>>>>> vma = find_vma();
>>>>>>>> handle_pte_fault(vma);
>>>>>>>> if retry
>>>>>>>> unlock(mmap_sem)
>>>>>>>> goto again;
>>>>>>>> done:
>>>>>>>> handle fault error
>>>>>>>> }
>>>>>>>>
>>>>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>>>>
>>>>>>>> This series add a new software performance event named 'speculative-faults'
>>>>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>>>>> the part of the faults processed speculatively.
>>>>>>>>
>>>>>>>> There are some trace events introduced by this series. They allow
>>>>>>>> identifying why the page faults were not processed speculatively. This
>>>>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>>>>> grouped in a system named 'pagefault', they are:
>>>>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>>>>> back.
>>>>>>>>
>>>>>>>> To record all the related events, the easier is to run perf with the
>>>>>>>> following arguments :
>>>>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>>>>
>>>>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>>>>> page fault handled speculatively. I can be seen this way:
>>>>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>>>>
>>>>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>>>>> on x86, PowerPC and arm64.
>>>>>>>>
>>>>>>>> ---------------------
>>>>>>>> Real Workload results
>>>>>>>>
>>>>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>>>>> this new version should not impact the performance boost seen.
>>>>>>>>
>>>>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>>>>> series:
>>>>>>>> vanilla spf
>>>>>>>> faults 89.418 101.364 +13%
>>>>>>>> spf n/a 97.989
>>>>>>>>
>>>>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>>>>> way.
>>>>>>>>
>>>>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>>>>> it a try on an android device. He reported that the application launch time
>>>>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>>>>> 20%.
>>>>>>>>
>>>>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>>>>
>>>>>>>> Application 4.9 4.9+spf delta
>>>>>>>> com.tencent.mm 416 389 -7%
>>>>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>>>>> com.tencent.mtt 455 454 0%
>>>>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>>>>> com.autonavi.minimap 711 701 -1%
>>>>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>>>>> com.immomo.momo 501 487 -3%
>>>>>>>> com.tencent.peng 2145 2112 -2%
>>>>>>>> com.smile.gifmaker 491 461 -6%
>>>>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>>>>> com.taobao.taobao 1341 1198 -11%
>>>>>>>> com.baidu.searchbox 333 314 -6%
>>>>>>>> com.tencent.mobileqq 394 384 -3%
>>>>>>>> com.sina.weibo 907 906 0%
>>>>>>>> com.youku.phone 816 731 -11%
>>>>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>>>>> com.UCMobile 415 411 -1%
>>>>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>>>>> com.tencent.qqmusic 336 329 -2%
>>>>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>>>>
>>>>>>>> ------------------
>>>>>>>> Benchmarks results
>>>>>>>>
>>>>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>>>>> SPF is BASE + this series
>>>>>>>>
>>>>>>>> Kernbench:
>>>>>>>> ----------
>>>>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>>>>> kernel (kernel is build 5 times):
>>>>>>>>
>>>>>>>> Average Half load -j 8
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>>>>
>>>>>>>> Average Optimal load -j 16
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>>>>
>>>>>>>>
>>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>>> 526743764 faults
>>>>>>>> 210 spf
>>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 2278 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> Very few speculative page faults were recorded as most of the processes
>>>>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>>>>> were created during the kernel build processing).
>>>>>>>>
>>>>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>>>>
>>>>>>>> Average Half load -j 40
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>>>>
>>>>>>>> Average Optimal load -j 80
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>>>>
>>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>>> 116730856 faults
>>>>>>>> 0 spf
>>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 476 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>>>>> there is no impact on the performance.
>>>>>>>>
>>>>>>>> Ebizzy:
>>>>>>>> -------
>>>>>>>> The test is counting the number of records per second it can manage, the
>>>>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>>>>> consistent result I repeated the test 100 times and measure the average
>>>>>>>> result. The number is the record processes per second, the higher is the
>>>>>>>> best.
>>>>>>>>
>>>>>>>> BASE SPF delta
>>>>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>>>>
>>>>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>>>>> 1706379 faults
>>>>>>>> 1674599 spf
>>>>>>>> 30588 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 363 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>>>>> 1874773 faults
>>>>>>>> 1461153 spf
>>>>>>>> 413293 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 200 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>>>>> leading the ebizzy performance boost.
>>>>>>>>
>>>>>>>> ------------------
>>>>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>>>>> and Minchan Kim, hopefully.
>>>>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>>>>> __do_page_fault().
>>>>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>>>>> instead
>>>>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>>>>> useless
>>>>>>>> trace event pagefault:spf_pte_lock.
>>>>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>>>>> additional tests done didn't show a significant performance improvement.
>>>>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>>>>
>>>>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>>>>
>>>>>>>>
>>>>>>>> Laurent Dufour (20):
>>>>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>>>>> mm: make pte_unmap_same compatible with SPF
>>>>>>>> mm: introduce INIT_VMA()
>>>>>>>> mm: protect VMA modifications using VMA sequence count
>>>>>>>> mm: protect mremap() against SPF hanlder
>>>>>>>> mm: protect SPF handler against anon_vma changes
>>>>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>>>>> mm: introduce __vm_normal_page()
>>>>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>>>>> mm: protect mm_rb tree with a rwlock
>>>>>>>> mm: adding speculative page fault failure trace events
>>>>>>>> perf: add a speculative page fault sw event
>>>>>>>> perf tools: add support for the SPF perf event
>>>>>>>> mm: add speculative page fault vmstats
>>>>>>>> powerpc/mm: add speculative page fault
>>>>>>>>
>>>>>>>> Mahendran Ganesh (2):
>>>>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>>> arm64/mm: add speculative page fault
>>>>>>>>
>>>>>>>> Peter Zijlstra (4):
>>>>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>>>>> mm: VMA sequence count
>>>>>>>> mm: provide speculative fault infrastructure
>>>>>>>> x86/mm: add speculative pagefault handling
>>>>>>>>
>>>>>>>> arch/arm64/Kconfig | 1 +
>>>>>>>> arch/arm64/mm/fault.c | 12 +
>>>>>>>> arch/powerpc/Kconfig | 1 +
>>>>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>>>>> arch/x86/Kconfig | 1 +
>>>>>>>> arch/x86/mm/fault.c | 27 +-
>>>>>>>> fs/exec.c | 2 +-
>>>>>>>> fs/proc/task_mmu.c | 5 +-
>>>>>>>> fs/userfaultfd.c | 17 +-
>>>>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>>>>> include/linux/migrate.h | 4 +-
>>>>>>>> include/linux/mm.h | 136 +++++++-
>>>>>>>> include/linux/mm_types.h | 7 +
>>>>>>>> include/linux/pagemap.h | 4 +-
>>>>>>>> include/linux/rmap.h | 12 +-
>>>>>>>> include/linux/swap.h | 10 +-
>>>>>>>> include/linux/vm_event_item.h | 3 +
>>>>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>>>>> kernel/fork.c | 5 +-
>>>>>>>> mm/Kconfig | 22 ++
>>>>>>>> mm/huge_memory.c | 6 +-
>>>>>>>> mm/hugetlb.c | 2 +
>>>>>>>> mm/init-mm.c | 3 +
>>>>>>>> mm/internal.h | 20 ++
>>>>>>>> mm/khugepaged.c | 5 +
>>>>>>>> mm/madvise.c | 6 +-
>>>>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>>>>> mm/mempolicy.c | 51 ++-
>>>>>>>> mm/migrate.c | 6 +-
>>>>>>>> mm/mlock.c | 13 +-
>>>>>>>> mm/mmap.c | 229 ++++++++++---
>>>>>>>> mm/mprotect.c | 4 +-
>>>>>>>> mm/mremap.c | 13 +
>>>>>>>> mm/nommu.c | 2 +-
>>>>>>>> mm/rmap.c | 5 +-
>>>>>>>> mm/swap.c | 6 +-
>>>>>>>> mm/swap_state.c | 8 +-
>>>>>>>> mm/vmstat.c | 5 +-
>>>>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>>>>> tools/perf/util/evsel.c | 1 +
>>>>>>>> tools/perf/util/parse-events.c | 4 +
>>>>>>>> tools/perf/util/parse-events.l | 1 +
>>>>>>>> tools/perf/util/python.c | 1 +
>>>>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>>>>
>>>>>>>> --
>>>>>>>> 2.7.4
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>
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^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-08-03 6:36 ` Song, HaiyanX
2018-08-03 6:45 ` Song, HaiyanX
@ 2018-08-22 14:23 ` Laurent Dufour
2018-09-18 6:42 ` Song, HaiyanX
1 sibling, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2018-08-22 14:23 UTC (permalink / raw)
To: Song, HaiyanX
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
[-- Attachment #1: Type: text/plain, Size: 43707 bytes --]
On 03/08/2018 08:36, Song, HaiyanX wrote:
> Hi Laurent,
Hi Haiyan,
Sorry for the late answer, I was off a couple of days.
>
> Thanks for your analysis for the last perf results.
> Your mentioned ," the major differences at the head of the perf report is the 92% testcase which is weirdly not reported
> on the head side", which is a bug of 0-day,and it caused the item is not counted in perf.
>
> I've triggered the test page_fault2 and page_fault3 again only with thread mode of will-it-scale on 0-day (on the same test box,every case tested 3 times).
> I checked the perf report have no above mentioned problem.
>
> I have compared them, found some items have difference, such as below case:
> page_fault2-thp-always: handle_mm_fault, base: 45.22% head: 29.41%
> page_fault3-thp-always: handle_mm_fault, base: 22.95% head: 14.15%
These would mean that the system spends lees time running handle_mm_fault()
when SPF is in the picture in this 2 cases which is good. This should lead to
better results with the SPF series, and I can't find any values higher on the
head side.
>
> So i attached the perf result in mail again, could your have a look again for checking the difference between base and head commit.
I took a close look to all the perf result you sent, but I can't identify any
major difference. But the compiler optimization is getting rid of the
handle_pte_fault() symbol on the base kernel which add complexity to check the
differences.
To get rid of that, I'm proposing that you applied the attached patch to the
spf kernel. This patch is allowing to turn on/off the SPF handler through
/proc/sys/vm/speculative_page_fault.
This should ease the testing by limiting the reboot and avoid kernel's symbols
mismatch. Obviously there is still a small overhead due to the check but it
should not be viewable.
With this patch applied you can simply run
echo 1 > /proc/sys/vm/speculative_page_fault
to run a test with the speculative page fault handler activated. Or run
echo 0 > /proc/sys/vm/speculative_page_fault
to run a test without it.
I'm really sorry to asking that again, but could please run the test
page_fault3_base_THP-Always with and without SPF and capture the perf output.
I think we should focus on that test which showed the biggest regression.
Thanks,
Laurent.
>
> Thanks,
> Haiyan, Song
>
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Tuesday, July 17, 2018 5:36 PM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> On 13/07/2018 05:56, Song, HaiyanX wrote:
>> Hi Laurent,
>
> Hi Haiyan,
>
> Thanks a lot for sharing this perf reports.
>
> I looked at them closely, and I've to admit that I was not able to found a
> major difference between the base and the head report, except that
> handle_pte_fault() is no more in-lined in the head one.
>
> As expected, __handle_speculative_fault() is never traced since these tests are
> dealing with file mapping, not handled in the speculative way.
>
> When running these test did you seen a major differences in the test's result
> between base and head ?
>
> From the number of cycles counted, the biggest difference is page_fault3 when
> run with the THP enabled:
> BASE HEAD Delta
> page_fault2_base_thp_never 1142252426747 1065866197589 -6.69%
> page_fault2_base_THP-Alwasys 1124844374523 1076312228927 -4.31%
> page_fault3_base_thp_never 1099387298152 1134118402345 3.16%
> page_fault3_base_THP-Always 1059370178101 853985561949 -19.39%
>
>
> The very weird thing is the difference of the delta cycles reported between
> thp never and thp always, because the speculative way is aborted when checking
> for the vma->ops field, which is the same in both case, and the thp is never
> checked. So there is no code covering differnce, on the speculative path,
> between these 2 cases. This leads me to think that there are other interactions
> interfering in the measure.
>
> Looking at the perf-profile_page_fault3_*_THP-Always, the major differences at
> the head of the perf report is the 92% testcase which is weirdly not reported
> on the head side :
> 92.02% 22.33% page_fault3_processes [.] testcase
> 92.02% testcase
>
> Then the base reported 37.67% for __do_page_fault() where the head reported
> 48.41%, but the only difference in this function, between base and head, is the
> call to handle_speculative_fault(). But this is a macro checking for the fault
> flags, and mm->users and then calling __handle_speculative_fault() if needed.
> So this can't explain this difference, except if __handle_speculative_fault()
> is inlined in __do_page_fault().
> Is this the case on your build ?
>
> Haiyan, do you still have the output of the test to check those numbers too ?
>
> Cheers,
> Laurent
>
>> I attached the perf-profile.gz file for case page_fault2 and page_fault3. These files were captured during test the related test case.
>> Please help to check on these data if it can help you to find the higher change. Thanks.
>>
>> File name perf-profile_page_fault2_head_THP-Always.gz, means the perf-profile result get from page_fault2
>> tested for head commit (a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12) with THP_always configuration.
>>
>> Best regards,
>> Haiyan Song
>>
>> ________________________________________
>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>> Sent: Thursday, July 12, 2018 1:05 AM
>> To: Song, HaiyanX
>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>
>> Hi Haiyan,
>>
>> Do you get a chance to capture some performance cycles on your system ?
>> I still can't get these numbers on my hardware.
>>
>> Thanks,
>> Laurent.
>>
>> On 04/07/2018 09:51, Laurent Dufour wrote:
>>> On 04/07/2018 05:23, Song, HaiyanX wrote:
>>>> Hi Laurent,
>>>>
>>>>
>>>> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
>>>> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
>>>
>>> Repeating the test only 3 times seems a bit too low to me.
>>>
>>> I'll focus on the higher change for the moment, but I don't have access to such
>>> a hardware.
>>>
>>> Is possible to provide a diff between base and SPF of the performance cycles
>>> measured when running page_fault3 and page_fault2 when the 20% change is detected.
>>>
>>> Please stay focus on the test case process to see exactly where the series is
>>> impacting.
>>>
>>> Thanks,
>>> Laurent.
>>>
>>>>
>>>> And I did not find other high variation on test case result.
>>>>
>>>> a). Enable THP
>>>> testcase base stddev change head stddev metric
>>>> page_fault3/enable THP 10519 +- 3% -20.5% 8368 +-6% will-it-scale.per_thread_ops
>>>> page_fault2/enalbe THP 8281 +- 2% -18.8% 6728 will-it-scale.per_thread_ops
>>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>>
>>>> b). Disable THP
>>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>>
>>>>
>>>> Best regards,
>>>> Haiyan Song
>>>> ________________________________________
>>>> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Monday, July 02, 2018 4:59 PM
>>>> To: Song, HaiyanX
>>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> On 11/06/2018 09:49, Song, HaiyanX wrote:
>>>>> Hi Laurent,
>>>>>
>>>>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>>>>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>>>>> V9 patch serials.
>>>>>
>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>>>>> commit id:
>>>>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>>>>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>>>>> Benchmark: will-it-scale
>>>>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>>>>
>>>>> Metrics:
>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>> THP: enable / disable
>>>>> nr_task:100%
>>>>>
>>>>> 1. Regressions:
>>>>>
>>>>> a). Enable THP
>>>>> testcase base change head metric
>>>>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>>>>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>>>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>>>
>>>>> b). Disable THP
>>>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>>>
>>>>> Notes: for the above values of test result, the higher is better.
>>>>
>>>> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
>>>> get reproducible results. The results have huge variation, even on the vanilla
>>>> kernel, and I can't state on any changes due to that.
>>>>
>>>> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
>>>> measure any changes between the vanilla and the SPF patched ones:
>>>>
>>>> test THP enabled 4.17.0-rc4-mm1 spf delta
>>>> page_fault3_threads 2697.7 2683.5 -0.53%
>>>> page_fault2_threads 170660.6 169574.1 -0.64%
>>>> context_switch1_threads 6915269.2 6877507.3 -0.55%
>>>> context_switch1_processes 6478076.2 6529493.5 0.79%
>>>> brk1 243391.2 238527.5 -2.00%
>>>>
>>>> Tests were run 10 times, no high variation detected.
>>>>
>>>> Did you see high variation on your side ? How many times the test were run to
>>>> compute the average values ?
>>>>
>>>> Thanks,
>>>> Laurent.
>>>>
>>>>
>>>>>
>>>>> 2. Improvement: not found improvement based on the selected test cases.
>>>>>
>>>>>
>>>>> Best regards
>>>>> Haiyan Song
>>>>> ________________________________________
>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>> Sent: Monday, May 28, 2018 4:54 PM
>>>>> To: Song, HaiyanX
>>>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>>>
>>>>> On 28/05/2018 10:22, Haiyan Song wrote:
>>>>>> Hi Laurent,
>>>>>>
>>>>>> Yes, these tests are done on V9 patch.
>>>>>
>>>>> Do you plan to give this V11 a run ?
>>>>>
>>>>>>
>>>>>>
>>>>>> Best regards,
>>>>>> Haiyan Song
>>>>>>
>>>>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>>>>
>>>>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>>>>> tested on Intel 4s Skylake platform.
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>>>>> series" while responding to the v11 header series...
>>>>>>> Were these tests done on v9 or v11 ?
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Laurent.
>>>>>>>
>>>>>>>>
>>>>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>>>>> Commit id:
>>>>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>>>>> Benchmark suite: will-it-scale
>>>>>>>> Download link:
>>>>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>>>>> Metrics:
>>>>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>>>>> THP: enable / disable
>>>>>>>> nr_task: 100%
>>>>>>>>
>>>>>>>> 1. Regressions:
>>>>>>>> a) THP enabled:
>>>>>>>> testcase base change head metric
>>>>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>>>>
>>>>>>>> b) THP disabled:
>>>>>>>> testcase base change head metric
>>>>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>>>>
>>>>>>>> 2. Improvements:
>>>>>>>> a) THP enabled:
>>>>>>>> testcase base change head metric
>>>>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>>>>
>>>>>>>> b) THP disabled:
>>>>>>>> testcase base change head metric
>>>>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>>>>
>>>>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>>>>
>>>>>>>>
>>>>>>>> Best regards
>>>>>>>> Haiyan Song
>>>>>>>>
>>>>>>>> ________________________________________
>>>>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>>>>
>>>>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>>>>> page fault without holding the mm semaphore [1].
>>>>>>>>
>>>>>>>> The idea is to try to handle user space page faults without holding the
>>>>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>>>>> process since the page fault handler will not wait for other threads memory
>>>>>>>> layout change to be done, assuming that this change is done in another part
>>>>>>>> of the process's memory space. This type page fault is named speculative
>>>>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>>>>> is failing its processing and a classic page fault is then tried.
>>>>>>>>
>>>>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>>>>> limiting the locking contention to these operations which are expected to
>>>>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>>>>> benchmark anymore.
>>>>>>>>
>>>>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>>>>> have to be protected against parallel changes. This is done by using a per
>>>>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>>>>> speculative page fault in that case.
>>>>>>>>
>>>>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>>>>> checked during the page fault are modified.
>>>>>>>>
>>>>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>>>>> parallel change is possible at this time.
>>>>>>>>
>>>>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>>>>> classic page fault handler will be called to handle the operation while
>>>>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>>>>> PTE.
>>>>>>>>
>>>>>>>> In pseudo code, this could be seen as:
>>>>>>>> speculative_page_fault()
>>>>>>>> {
>>>>>>>> vma = get_vma()
>>>>>>>> check vma sequence count
>>>>>>>> check vma's support
>>>>>>>> disable interrupt
>>>>>>>> check pgd,p4d,...,pte
>>>>>>>> save pmd and pte in vmf
>>>>>>>> save vma sequence counter in vmf
>>>>>>>> enable interrupt
>>>>>>>> check vma sequence count
>>>>>>>> handle_pte_fault(vma)
>>>>>>>> ..
>>>>>>>> page = alloc_page()
>>>>>>>> pte_map_lock()
>>>>>>>> disable interrupt
>>>>>>>> abort if sequence counter has changed
>>>>>>>> abort if pmd or pte has changed
>>>>>>>> pte map and lock
>>>>>>>> enable interrupt
>>>>>>>> if abort
>>>>>>>> free page
>>>>>>>> abort
>>>>>>>> ...
>>>>>>>> }
>>>>>>>>
>>>>>>>> arch_fault_handler()
>>>>>>>> {
>>>>>>>> if (speculative_page_fault(&vma))
>>>>>>>> goto done
>>>>>>>> again:
>>>>>>>> lock(mmap_sem)
>>>>>>>> vma = find_vma();
>>>>>>>> handle_pte_fault(vma);
>>>>>>>> if retry
>>>>>>>> unlock(mmap_sem)
>>>>>>>> goto again;
>>>>>>>> done:
>>>>>>>> handle fault error
>>>>>>>> }
>>>>>>>>
>>>>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>>>>
>>>>>>>> This series add a new software performance event named 'speculative-faults'
>>>>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>>>>> the part of the faults processed speculatively.
>>>>>>>>
>>>>>>>> There are some trace events introduced by this series. They allow
>>>>>>>> identifying why the page faults were not processed speculatively. This
>>>>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>>>>> grouped in a system named 'pagefault', they are:
>>>>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>>>>> back.
>>>>>>>>
>>>>>>>> To record all the related events, the easier is to run perf with the
>>>>>>>> following arguments :
>>>>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>>>>
>>>>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>>>>> page fault handled speculatively. I can be seen this way:
>>>>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>>>>
>>>>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>>>>> on x86, PowerPC and arm64.
>>>>>>>>
>>>>>>>> ---------------------
>>>>>>>> Real Workload results
>>>>>>>>
>>>>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>>>>> this new version should not impact the performance boost seen.
>>>>>>>>
>>>>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>>>>> series:
>>>>>>>> vanilla spf
>>>>>>>> faults 89.418 101.364 +13%
>>>>>>>> spf n/a 97.989
>>>>>>>>
>>>>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>>>>> way.
>>>>>>>>
>>>>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>>>>> it a try on an android device. He reported that the application launch time
>>>>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>>>>> 20%.
>>>>>>>>
>>>>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>>>>
>>>>>>>> Application 4.9 4.9+spf delta
>>>>>>>> com.tencent.mm 416 389 -7%
>>>>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>>>>> com.tencent.mtt 455 454 0%
>>>>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>>>>> com.autonavi.minimap 711 701 -1%
>>>>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>>>>> com.immomo.momo 501 487 -3%
>>>>>>>> com.tencent.peng 2145 2112 -2%
>>>>>>>> com.smile.gifmaker 491 461 -6%
>>>>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>>>>> com.taobao.taobao 1341 1198 -11%
>>>>>>>> com.baidu.searchbox 333 314 -6%
>>>>>>>> com.tencent.mobileqq 394 384 -3%
>>>>>>>> com.sina.weibo 907 906 0%
>>>>>>>> com.youku.phone 816 731 -11%
>>>>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>>>>> com.UCMobile 415 411 -1%
>>>>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>>>>> com.tencent.qqmusic 336 329 -2%
>>>>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>>>>
>>>>>>>> ------------------
>>>>>>>> Benchmarks results
>>>>>>>>
>>>>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>>>>> SPF is BASE + this series
>>>>>>>>
>>>>>>>> Kernbench:
>>>>>>>> ----------
>>>>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>>>>> kernel (kernel is build 5 times):
>>>>>>>>
>>>>>>>> Average Half load -j 8
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>>>>
>>>>>>>> Average Optimal load -j 16
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>>>>
>>>>>>>>
>>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>>> 526743764 faults
>>>>>>>> 210 spf
>>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 2278 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> Very few speculative page faults were recorded as most of the processes
>>>>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>>>>> were created during the kernel build processing).
>>>>>>>>
>>>>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>>>>
>>>>>>>> Average Half load -j 40
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>>>>
>>>>>>>> Average Optimal load -j 80
>>>>>>>> Run (std deviation)
>>>>>>>> BASE SPF
>>>>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>>>>
>>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>>> 116730856 faults
>>>>>>>> 0 spf
>>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 476 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>>>>> there is no impact on the performance.
>>>>>>>>
>>>>>>>> Ebizzy:
>>>>>>>> -------
>>>>>>>> The test is counting the number of records per second it can manage, the
>>>>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>>>>> consistent result I repeated the test 100 times and measure the average
>>>>>>>> result. The number is the record processes per second, the higher is the
>>>>>>>> best.
>>>>>>>>
>>>>>>>> BASE SPF delta
>>>>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>>>>
>>>>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>>>>> 1706379 faults
>>>>>>>> 1674599 spf
>>>>>>>> 30588 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 363 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>>>>> 1874773 faults
>>>>>>>> 1461153 spf
>>>>>>>> 413293 pagefault:spf_vma_changed
>>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>>> 200 pagefault:spf_vma_notsup
>>>>>>>> 0 pagefault:spf_vma_access
>>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>>
>>>>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>>>>> leading the ebizzy performance boost.
>>>>>>>>
>>>>>>>> ------------------
>>>>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>>>>> and Minchan Kim, hopefully.
>>>>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>>>>> __do_page_fault().
>>>>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>>>>> instead
>>>>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>>>>> useless
>>>>>>>> trace event pagefault:spf_pte_lock.
>>>>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>>>>> additional tests done didn't show a significant performance improvement.
>>>>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>>>>
>>>>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>>>>
>>>>>>>>
>>>>>>>> Laurent Dufour (20):
>>>>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>>>>> mm: make pte_unmap_same compatible with SPF
>>>>>>>> mm: introduce INIT_VMA()
>>>>>>>> mm: protect VMA modifications using VMA sequence count
>>>>>>>> mm: protect mremap() against SPF hanlder
>>>>>>>> mm: protect SPF handler against anon_vma changes
>>>>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>>>>> mm: introduce __vm_normal_page()
>>>>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>>>>> mm: protect mm_rb tree with a rwlock
>>>>>>>> mm: adding speculative page fault failure trace events
>>>>>>>> perf: add a speculative page fault sw event
>>>>>>>> perf tools: add support for the SPF perf event
>>>>>>>> mm: add speculative page fault vmstats
>>>>>>>> powerpc/mm: add speculative page fault
>>>>>>>>
>>>>>>>> Mahendran Ganesh (2):
>>>>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>>> arm64/mm: add speculative page fault
>>>>>>>>
>>>>>>>> Peter Zijlstra (4):
>>>>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>>>>> mm: VMA sequence count
>>>>>>>> mm: provide speculative fault infrastructure
>>>>>>>> x86/mm: add speculative pagefault handling
>>>>>>>>
>>>>>>>> arch/arm64/Kconfig | 1 +
>>>>>>>> arch/arm64/mm/fault.c | 12 +
>>>>>>>> arch/powerpc/Kconfig | 1 +
>>>>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>>>>> arch/x86/Kconfig | 1 +
>>>>>>>> arch/x86/mm/fault.c | 27 +-
>>>>>>>> fs/exec.c | 2 +-
>>>>>>>> fs/proc/task_mmu.c | 5 +-
>>>>>>>> fs/userfaultfd.c | 17 +-
>>>>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>>>>> include/linux/migrate.h | 4 +-
>>>>>>>> include/linux/mm.h | 136 +++++++-
>>>>>>>> include/linux/mm_types.h | 7 +
>>>>>>>> include/linux/pagemap.h | 4 +-
>>>>>>>> include/linux/rmap.h | 12 +-
>>>>>>>> include/linux/swap.h | 10 +-
>>>>>>>> include/linux/vm_event_item.h | 3 +
>>>>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>>>>> kernel/fork.c | 5 +-
>>>>>>>> mm/Kconfig | 22 ++
>>>>>>>> mm/huge_memory.c | 6 +-
>>>>>>>> mm/hugetlb.c | 2 +
>>>>>>>> mm/init-mm.c | 3 +
>>>>>>>> mm/internal.h | 20 ++
>>>>>>>> mm/khugepaged.c | 5 +
>>>>>>>> mm/madvise.c | 6 +-
>>>>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>>>>> mm/mempolicy.c | 51 ++-
>>>>>>>> mm/migrate.c | 6 +-
>>>>>>>> mm/mlock.c | 13 +-
>>>>>>>> mm/mmap.c | 229 ++++++++++---
>>>>>>>> mm/mprotect.c | 4 +-
>>>>>>>> mm/mremap.c | 13 +
>>>>>>>> mm/nommu.c | 2 +-
>>>>>>>> mm/rmap.c | 5 +-
>>>>>>>> mm/swap.c | 6 +-
>>>>>>>> mm/swap_state.c | 8 +-
>>>>>>>> mm/vmstat.c | 5 +-
>>>>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>>>>> tools/perf/util/evsel.c | 1 +
>>>>>>>> tools/perf/util/parse-events.c | 4 +
>>>>>>>> tools/perf/util/parse-events.l | 1 +
>>>>>>>> tools/perf/util/python.c | 1 +
>>>>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>>>>
>>>>>>>> --
>>>>>>>> 2.7.4
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-mm-Add-a-speculative-page-fault-switch-in-sysctl.patch --]
[-- Type: text/x-patch; name="0001-mm-Add-a-speculative-page-fault-switch-in-sysctl.patch", Size: 0 bytes --]
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-08-03 6:36 ` Song, HaiyanX
@ 2018-08-03 6:45 ` Song, HaiyanX
2018-08-22 14:23 ` Laurent Dufour
1 sibling, 0 replies; 46+ messages in thread
From: Song, HaiyanX @ 2018-08-03 6:45 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
[-- Attachment #1: Type: text/plain, Size: 43157 bytes --]
Add another 3 perf file.
________________________________________
From: Song, HaiyanX
Sent: Friday, August 03, 2018 2:36 PM
To: Laurent Dufour
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: RE: [PATCH v11 00/26] Speculative page faults
Hi Laurent,
Thanks for your analysis for the last perf results.
Your mentioned ," the major differences at the head of the perf report is the 92% testcase which is weirdly not reported
on the head side", which is a bug of 0-day,and it caused the item is not counted in perf.
I've triggered the test page_fault2 and page_fault3 again only with thread mode of will-it-scale on 0-day (on the same test box,every case tested 3 times).
I checked the perf report have no above mentioned problem.
I have compared them, found some items have difference, such as below case:
page_fault2-thp-always: handle_mm_fault, base: 45.22% head: 29.41%
page_fault3-thp-always: handle_mm_fault, base: 22.95% head: 14.15%
So i attached the perf result in mail again, could your have a look again for checking the difference between base and head commit.
Thanks,
Haiyan, Song
________________________________________
From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
Sent: Tuesday, July 17, 2018 5:36 PM
To: Song, HaiyanX
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: Re: [PATCH v11 00/26] Speculative page faults
On 13/07/2018 05:56, Song, HaiyanX wrote:
> Hi Laurent,
Hi Haiyan,
Thanks a lot for sharing this perf reports.
I looked at them closely, and I've to admit that I was not able to found a
major difference between the base and the head report, except that
handle_pte_fault() is no more in-lined in the head one.
As expected, __handle_speculative_fault() is never traced since these tests are
dealing with file mapping, not handled in the speculative way.
When running these test did you seen a major differences in the test's result
between base and head ?
>From the number of cycles counted, the biggest difference is page_fault3 when
run with the THP enabled:
BASE HEAD Delta
page_fault2_base_thp_never 1142252426747 1065866197589 -6.69%
page_fault2_base_THP-Alwasys 1124844374523 1076312228927 -4.31%
page_fault3_base_thp_never 1099387298152 1134118402345 3.16%
page_fault3_base_THP-Always 1059370178101 853985561949 -19.39%
The very weird thing is the difference of the delta cycles reported between
thp never and thp always, because the speculative way is aborted when checking
for the vma->ops field, which is the same in both case, and the thp is never
checked. So there is no code covering differnce, on the speculative path,
between these 2 cases. This leads me to think that there are other interactions
interfering in the measure.
Looking at the perf-profile_page_fault3_*_THP-Always, the major differences at
the head of the perf report is the 92% testcase which is weirdly not reported
on the head side :
92.02% 22.33% page_fault3_processes [.] testcase
92.02% testcase
Then the base reported 37.67% for __do_page_fault() where the head reported
48.41%, but the only difference in this function, between base and head, is the
call to handle_speculative_fault(). But this is a macro checking for the fault
flags, and mm->users and then calling __handle_speculative_fault() if needed.
So this can't explain this difference, except if __handle_speculative_fault()
is inlined in __do_page_fault().
Is this the case on your build ?
Haiyan, do you still have the output of the test to check those numbers too ?
Cheers,
Laurent
> I attached the perf-profile.gz file for case page_fault2 and page_fault3. These files were captured during test the related test case.
> Please help to check on these data if it can help you to find the higher change. Thanks.
>
> File name perf-profile_page_fault2_head_THP-Always.gz, means the perf-profile result get from page_fault2
> tested for head commit (a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12) with THP_always configuration.
>
> Best regards,
> Haiyan Song
>
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Thursday, July 12, 2018 1:05 AM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> Hi Haiyan,
>
> Do you get a chance to capture some performance cycles on your system ?
> I still can't get these numbers on my hardware.
>
> Thanks,
> Laurent.
>
> On 04/07/2018 09:51, Laurent Dufour wrote:
>> On 04/07/2018 05:23, Song, HaiyanX wrote:
>>> Hi Laurent,
>>>
>>>
>>> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
>>> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
>>
>> Repeating the test only 3 times seems a bit too low to me.
>>
>> I'll focus on the higher change for the moment, but I don't have access to such
>> a hardware.
>>
>> Is possible to provide a diff between base and SPF of the performance cycles
>> measured when running page_fault3 and page_fault2 when the 20% change is detected.
>>
>> Please stay focus on the test case process to see exactly where the series is
>> impacting.
>>
>> Thanks,
>> Laurent.
>>
>>>
>>> And I did not find other high variation on test case result.
>>>
>>> a). Enable THP
>>> testcase base stddev change head stddev metric
>>> page_fault3/enable THP 10519 ± 3% -20.5% 8368 ±6% will-it-scale.per_thread_ops
>>> page_fault2/enalbe THP 8281 ± 2% -18.8% 6728 will-it-scale.per_thread_ops
>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>
>>> b). Disable THP
>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>
>>>
>>> Best regards,
>>> Haiyan Song
>>> ________________________________________
>>> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Monday, July 02, 2018 4:59 PM
>>> To: Song, HaiyanX
>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>
>>> On 11/06/2018 09:49, Song, HaiyanX wrote:
>>>> Hi Laurent,
>>>>
>>>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>>>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>>>> V9 patch serials.
>>>>
>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>>>> commit id:
>>>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>>>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>>>> Benchmark: will-it-scale
>>>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>>>
>>>> Metrics:
>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>> THP: enable / disable
>>>> nr_task:100%
>>>>
>>>> 1. Regressions:
>>>>
>>>> a). Enable THP
>>>> testcase base change head metric
>>>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>>>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>>
>>>> b). Disable THP
>>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>>
>>>> Notes: for the above values of test result, the higher is better.
>>>
>>> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
>>> get reproducible results. The results have huge variation, even on the vanilla
>>> kernel, and I can't state on any changes due to that.
>>>
>>> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
>>> measure any changes between the vanilla and the SPF patched ones:
>>>
>>> test THP enabled 4.17.0-rc4-mm1 spf delta
>>> page_fault3_threads 2697.7 2683.5 -0.53%
>>> page_fault2_threads 170660.6 169574.1 -0.64%
>>> context_switch1_threads 6915269.2 6877507.3 -0.55%
>>> context_switch1_processes 6478076.2 6529493.5 0.79%
>>> brk1 243391.2 238527.5 -2.00%
>>>
>>> Tests were run 10 times, no high variation detected.
>>>
>>> Did you see high variation on your side ? How many times the test were run to
>>> compute the average values ?
>>>
>>> Thanks,
>>> Laurent.
>>>
>>>
>>>>
>>>> 2. Improvement: not found improvement based on the selected test cases.
>>>>
>>>>
>>>> Best regards
>>>> Haiyan Song
>>>> ________________________________________
>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Monday, May 28, 2018 4:54 PM
>>>> To: Song, HaiyanX
>>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> On 28/05/2018 10:22, Haiyan Song wrote:
>>>>> Hi Laurent,
>>>>>
>>>>> Yes, these tests are done on V9 patch.
>>>>
>>>> Do you plan to give this V11 a run ?
>>>>
>>>>>
>>>>>
>>>>> Best regards,
>>>>> Haiyan Song
>>>>>
>>>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>>>
>>>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>>>> tested on Intel 4s Skylake platform.
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>>>> series" while responding to the v11 header series...
>>>>>> Were these tests done on v9 or v11 ?
>>>>>>
>>>>>> Cheers,
>>>>>> Laurent.
>>>>>>
>>>>>>>
>>>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>>>> Commit id:
>>>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>>>> Benchmark suite: will-it-scale
>>>>>>> Download link:
>>>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>>>> Metrics:
>>>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>>>> THP: enable / disable
>>>>>>> nr_task: 100%
>>>>>>>
>>>>>>> 1. Regressions:
>>>>>>> a) THP enabled:
>>>>>>> testcase base change head metric
>>>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>>>
>>>>>>> b) THP disabled:
>>>>>>> testcase base change head metric
>>>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>>>
>>>>>>> 2. Improvements:
>>>>>>> a) THP enabled:
>>>>>>> testcase base change head metric
>>>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>>>
>>>>>>> b) THP disabled:
>>>>>>> testcase base change head metric
>>>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>>>
>>>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>>>
>>>>>>>
>>>>>>> Best regards
>>>>>>> Haiyan Song
>>>>>>>
>>>>>>> ________________________________________
>>>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>>>
>>>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>>>> page fault without holding the mm semaphore [1].
>>>>>>>
>>>>>>> The idea is to try to handle user space page faults without holding the
>>>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>>>> process since the page fault handler will not wait for other threads memory
>>>>>>> layout change to be done, assuming that this change is done in another part
>>>>>>> of the process's memory space. This type page fault is named speculative
>>>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>>>> is failing its processing and a classic page fault is then tried.
>>>>>>>
>>>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>>>> limiting the locking contention to these operations which are expected to
>>>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>>>> benchmark anymore.
>>>>>>>
>>>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>>>> have to be protected against parallel changes. This is done by using a per
>>>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>>>> speculative page fault in that case.
>>>>>>>
>>>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>>>> checked during the page fault are modified.
>>>>>>>
>>>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>>>> parallel change is possible at this time.
>>>>>>>
>>>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>>>> classic page fault handler will be called to handle the operation while
>>>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>>>> PTE.
>>>>>>>
>>>>>>> In pseudo code, this could be seen as:
>>>>>>> speculative_page_fault()
>>>>>>> {
>>>>>>> vma = get_vma()
>>>>>>> check vma sequence count
>>>>>>> check vma's support
>>>>>>> disable interrupt
>>>>>>> check pgd,p4d,...,pte
>>>>>>> save pmd and pte in vmf
>>>>>>> save vma sequence counter in vmf
>>>>>>> enable interrupt
>>>>>>> check vma sequence count
>>>>>>> handle_pte_fault(vma)
>>>>>>> ..
>>>>>>> page = alloc_page()
>>>>>>> pte_map_lock()
>>>>>>> disable interrupt
>>>>>>> abort if sequence counter has changed
>>>>>>> abort if pmd or pte has changed
>>>>>>> pte map and lock
>>>>>>> enable interrupt
>>>>>>> if abort
>>>>>>> free page
>>>>>>> abort
>>>>>>> ...
>>>>>>> }
>>>>>>>
>>>>>>> arch_fault_handler()
>>>>>>> {
>>>>>>> if (speculative_page_fault(&vma))
>>>>>>> goto done
>>>>>>> again:
>>>>>>> lock(mmap_sem)
>>>>>>> vma = find_vma();
>>>>>>> handle_pte_fault(vma);
>>>>>>> if retry
>>>>>>> unlock(mmap_sem)
>>>>>>> goto again;
>>>>>>> done:
>>>>>>> handle fault error
>>>>>>> }
>>>>>>>
>>>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>>>
>>>>>>> This series add a new software performance event named 'speculative-faults'
>>>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>>>> the part of the faults processed speculatively.
>>>>>>>
>>>>>>> There are some trace events introduced by this series. They allow
>>>>>>> identifying why the page faults were not processed speculatively. This
>>>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>>>> grouped in a system named 'pagefault', they are:
>>>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>>>> back.
>>>>>>>
>>>>>>> To record all the related events, the easier is to run perf with the
>>>>>>> following arguments :
>>>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>>>
>>>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>>>> page fault handled speculatively. I can be seen this way:
>>>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>>>
>>>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>>>> on x86, PowerPC and arm64.
>>>>>>>
>>>>>>> ---------------------
>>>>>>> Real Workload results
>>>>>>>
>>>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>>>> this new version should not impact the performance boost seen.
>>>>>>>
>>>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>>>> series:
>>>>>>> vanilla spf
>>>>>>> faults 89.418 101.364 +13%
>>>>>>> spf n/a 97.989
>>>>>>>
>>>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>>>> way.
>>>>>>>
>>>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>>>> it a try on an android device. He reported that the application launch time
>>>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>>>> 20%.
>>>>>>>
>>>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>>>
>>>>>>> Application 4.9 4.9+spf delta
>>>>>>> com.tencent.mm 416 389 -7%
>>>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>>>> com.tencent.mtt 455 454 0%
>>>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>>>> com.autonavi.minimap 711 701 -1%
>>>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>>>> com.immomo.momo 501 487 -3%
>>>>>>> com.tencent.peng 2145 2112 -2%
>>>>>>> com.smile.gifmaker 491 461 -6%
>>>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>>>> com.taobao.taobao 1341 1198 -11%
>>>>>>> com.baidu.searchbox 333 314 -6%
>>>>>>> com.tencent.mobileqq 394 384 -3%
>>>>>>> com.sina.weibo 907 906 0%
>>>>>>> com.youku.phone 816 731 -11%
>>>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>>>> com.UCMobile 415 411 -1%
>>>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>>>> com.tencent.qqmusic 336 329 -2%
>>>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>>>
>>>>>>> ------------------
>>>>>>> Benchmarks results
>>>>>>>
>>>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>>>> SPF is BASE + this series
>>>>>>>
>>>>>>> Kernbench:
>>>>>>> ----------
>>>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>>>> kernel (kernel is build 5 times):
>>>>>>>
>>>>>>> Average Half load -j 8
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>>>
>>>>>>> Average Optimal load -j 16
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>>>
>>>>>>>
>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>> 526743764 faults
>>>>>>> 210 spf
>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 2278 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> Very few speculative page faults were recorded as most of the processes
>>>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>>>> were created during the kernel build processing).
>>>>>>>
>>>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>>>
>>>>>>> Average Half load -j 40
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>>>
>>>>>>> Average Optimal load -j 80
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>>>
>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>> 116730856 faults
>>>>>>> 0 spf
>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 476 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>>>> there is no impact on the performance.
>>>>>>>
>>>>>>> Ebizzy:
>>>>>>> -------
>>>>>>> The test is counting the number of records per second it can manage, the
>>>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>>>> consistent result I repeated the test 100 times and measure the average
>>>>>>> result. The number is the record processes per second, the higher is the
>>>>>>> best.
>>>>>>>
>>>>>>> BASE SPF delta
>>>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>>>
>>>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>>>> 1706379 faults
>>>>>>> 1674599 spf
>>>>>>> 30588 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 363 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>>>> 1874773 faults
>>>>>>> 1461153 spf
>>>>>>> 413293 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 200 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>>>> leading the ebizzy performance boost.
>>>>>>>
>>>>>>> ------------------
>>>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>>>> and Minchan Kim, hopefully.
>>>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>>>> __do_page_fault().
>>>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>>>> instead
>>>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>>>> useless
>>>>>>> trace event pagefault:spf_pte_lock.
>>>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>>>> additional tests done didn't show a significant performance improvement.
>>>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>>>
>>>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>>>
>>>>>>>
>>>>>>> Laurent Dufour (20):
>>>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>>>> mm: make pte_unmap_same compatible with SPF
>>>>>>> mm: introduce INIT_VMA()
>>>>>>> mm: protect VMA modifications using VMA sequence count
>>>>>>> mm: protect mremap() against SPF hanlder
>>>>>>> mm: protect SPF handler against anon_vma changes
>>>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>>>> mm: introduce __vm_normal_page()
>>>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>>>> mm: protect mm_rb tree with a rwlock
>>>>>>> mm: adding speculative page fault failure trace events
>>>>>>> perf: add a speculative page fault sw event
>>>>>>> perf tools: add support for the SPF perf event
>>>>>>> mm: add speculative page fault vmstats
>>>>>>> powerpc/mm: add speculative page fault
>>>>>>>
>>>>>>> Mahendran Ganesh (2):
>>>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> arm64/mm: add speculative page fault
>>>>>>>
>>>>>>> Peter Zijlstra (4):
>>>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>>>> mm: VMA sequence count
>>>>>>> mm: provide speculative fault infrastructure
>>>>>>> x86/mm: add speculative pagefault handling
>>>>>>>
>>>>>>> arch/arm64/Kconfig | 1 +
>>>>>>> arch/arm64/mm/fault.c | 12 +
>>>>>>> arch/powerpc/Kconfig | 1 +
>>>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>>>> arch/x86/Kconfig | 1 +
>>>>>>> arch/x86/mm/fault.c | 27 +-
>>>>>>> fs/exec.c | 2 +-
>>>>>>> fs/proc/task_mmu.c | 5 +-
>>>>>>> fs/userfaultfd.c | 17 +-
>>>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>>>> include/linux/migrate.h | 4 +-
>>>>>>> include/linux/mm.h | 136 +++++++-
>>>>>>> include/linux/mm_types.h | 7 +
>>>>>>> include/linux/pagemap.h | 4 +-
>>>>>>> include/linux/rmap.h | 12 +-
>>>>>>> include/linux/swap.h | 10 +-
>>>>>>> include/linux/vm_event_item.h | 3 +
>>>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>>>> kernel/fork.c | 5 +-
>>>>>>> mm/Kconfig | 22 ++
>>>>>>> mm/huge_memory.c | 6 +-
>>>>>>> mm/hugetlb.c | 2 +
>>>>>>> mm/init-mm.c | 3 +
>>>>>>> mm/internal.h | 20 ++
>>>>>>> mm/khugepaged.c | 5 +
>>>>>>> mm/madvise.c | 6 +-
>>>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>>>> mm/mempolicy.c | 51 ++-
>>>>>>> mm/migrate.c | 6 +-
>>>>>>> mm/mlock.c | 13 +-
>>>>>>> mm/mmap.c | 229 ++++++++++---
>>>>>>> mm/mprotect.c | 4 +-
>>>>>>> mm/mremap.c | 13 +
>>>>>>> mm/nommu.c | 2 +-
>>>>>>> mm/rmap.c | 5 +-
>>>>>>> mm/swap.c | 6 +-
>>>>>>> mm/swap_state.c | 8 +-
>>>>>>> mm/vmstat.c | 5 +-
>>>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>>>> tools/perf/util/evsel.c | 1 +
>>>>>>> tools/perf/util/parse-events.c | 4 +
>>>>>>> tools/perf/util/parse-events.l | 1 +
>>>>>>> tools/perf/util/python.c | 1 +
>>>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>>>
>>>>>>> --
>>>>>>> 2.7.4
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
[-- Attachment #2: perf-profile_page_fault3_head_thp_always.gz --]
[-- Type: application/gzip, Size: 12909 bytes --]
[-- Attachment #3: perf-profile_page_fault3_head_thp_never.gz --]
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[-- Attachment #4: perf-profile_page_fault2_head_thp_never.gz --]
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^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-07-17 9:36 ` Laurent Dufour
@ 2018-08-03 6:36 ` Song, HaiyanX
2018-08-03 6:45 ` Song, HaiyanX
2018-08-22 14:23 ` Laurent Dufour
0 siblings, 2 replies; 46+ messages in thread
From: Song, HaiyanX @ 2018-08-03 6:36 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
[-- Attachment #1: Type: text/plain, Size: 42188 bytes --]
Hi Laurent,
Thanks for your analysis for the last perf results.
Your mentioned ," the major differences at the head of the perf report is the 92% testcase which is weirdly not reported
on the head side", which is a bug of 0-day,and it caused the item is not counted in perf.
I've triggered the test page_fault2 and page_fault3 again only with thread mode of will-it-scale on 0-day (on the same test box,every case tested 3 times).
I checked the perf report have no above mentioned problem.
I have compared them, found some items have difference, such as below case:
page_fault2-thp-always: handle_mm_fault, base: 45.22% head: 29.41%
page_fault3-thp-always: handle_mm_fault, base: 22.95% head: 14.15%
So i attached the perf result in mail again, could your have a look again for checking the difference between base and head commit.
Thanks,
Haiyan, Song
________________________________________
From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
Sent: Tuesday, July 17, 2018 5:36 PM
To: Song, HaiyanX
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: Re: [PATCH v11 00/26] Speculative page faults
On 13/07/2018 05:56, Song, HaiyanX wrote:
> Hi Laurent,
Hi Haiyan,
Thanks a lot for sharing this perf reports.
I looked at them closely, and I've to admit that I was not able to found a
major difference between the base and the head report, except that
handle_pte_fault() is no more in-lined in the head one.
As expected, __handle_speculative_fault() is never traced since these tests are
dealing with file mapping, not handled in the speculative way.
When running these test did you seen a major differences in the test's result
between base and head ?
>From the number of cycles counted, the biggest difference is page_fault3 when
run with the THP enabled:
BASE HEAD Delta
page_fault2_base_thp_never 1142252426747 1065866197589 -6.69%
page_fault2_base_THP-Alwasys 1124844374523 1076312228927 -4.31%
page_fault3_base_thp_never 1099387298152 1134118402345 3.16%
page_fault3_base_THP-Always 1059370178101 853985561949 -19.39%
The very weird thing is the difference of the delta cycles reported between
thp never and thp always, because the speculative way is aborted when checking
for the vma->ops field, which is the same in both case, and the thp is never
checked. So there is no code covering differnce, on the speculative path,
between these 2 cases. This leads me to think that there are other interactions
interfering in the measure.
Looking at the perf-profile_page_fault3_*_THP-Always, the major differences at
the head of the perf report is the 92% testcase which is weirdly not reported
on the head side :
92.02% 22.33% page_fault3_processes [.] testcase
92.02% testcase
Then the base reported 37.67% for __do_page_fault() where the head reported
48.41%, but the only difference in this function, between base and head, is the
call to handle_speculative_fault(). But this is a macro checking for the fault
flags, and mm->users and then calling __handle_speculative_fault() if needed.
So this can't explain this difference, except if __handle_speculative_fault()
is inlined in __do_page_fault().
Is this the case on your build ?
Haiyan, do you still have the output of the test to check those numbers too ?
Cheers,
Laurent
> I attached the perf-profile.gz file for case page_fault2 and page_fault3. These files were captured during test the related test case.
> Please help to check on these data if it can help you to find the higher change. Thanks.
>
> File name perf-profile_page_fault2_head_THP-Always.gz, means the perf-profile result get from page_fault2
> tested for head commit (a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12) with THP_always configuration.
>
> Best regards,
> Haiyan Song
>
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Thursday, July 12, 2018 1:05 AM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> Hi Haiyan,
>
> Do you get a chance to capture some performance cycles on your system ?
> I still can't get these numbers on my hardware.
>
> Thanks,
> Laurent.
>
> On 04/07/2018 09:51, Laurent Dufour wrote:
>> On 04/07/2018 05:23, Song, HaiyanX wrote:
>>> Hi Laurent,
>>>
>>>
>>> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
>>> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
>>
>> Repeating the test only 3 times seems a bit too low to me.
>>
>> I'll focus on the higher change for the moment, but I don't have access to such
>> a hardware.
>>
>> Is possible to provide a diff between base and SPF of the performance cycles
>> measured when running page_fault3 and page_fault2 when the 20% change is detected.
>>
>> Please stay focus on the test case process to see exactly where the series is
>> impacting.
>>
>> Thanks,
>> Laurent.
>>
>>>
>>> And I did not find other high variation on test case result.
>>>
>>> a). Enable THP
>>> testcase base stddev change head stddev metric
>>> page_fault3/enable THP 10519 ± 3% -20.5% 8368 ±6% will-it-scale.per_thread_ops
>>> page_fault2/enalbe THP 8281 ± 2% -18.8% 6728 will-it-scale.per_thread_ops
>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>
>>> b). Disable THP
>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>
>>>
>>> Best regards,
>>> Haiyan Song
>>> ________________________________________
>>> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Monday, July 02, 2018 4:59 PM
>>> To: Song, HaiyanX
>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>
>>> On 11/06/2018 09:49, Song, HaiyanX wrote:
>>>> Hi Laurent,
>>>>
>>>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>>>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>>>> V9 patch serials.
>>>>
>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>>>> commit id:
>>>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>>>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>>>> Benchmark: will-it-scale
>>>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>>>
>>>> Metrics:
>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>> THP: enable / disable
>>>> nr_task:100%
>>>>
>>>> 1. Regressions:
>>>>
>>>> a). Enable THP
>>>> testcase base change head metric
>>>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>>>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>>
>>>> b). Disable THP
>>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>>
>>>> Notes: for the above values of test result, the higher is better.
>>>
>>> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
>>> get reproducible results. The results have huge variation, even on the vanilla
>>> kernel, and I can't state on any changes due to that.
>>>
>>> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
>>> measure any changes between the vanilla and the SPF patched ones:
>>>
>>> test THP enabled 4.17.0-rc4-mm1 spf delta
>>> page_fault3_threads 2697.7 2683.5 -0.53%
>>> page_fault2_threads 170660.6 169574.1 -0.64%
>>> context_switch1_threads 6915269.2 6877507.3 -0.55%
>>> context_switch1_processes 6478076.2 6529493.5 0.79%
>>> brk1 243391.2 238527.5 -2.00%
>>>
>>> Tests were run 10 times, no high variation detected.
>>>
>>> Did you see high variation on your side ? How many times the test were run to
>>> compute the average values ?
>>>
>>> Thanks,
>>> Laurent.
>>>
>>>
>>>>
>>>> 2. Improvement: not found improvement based on the selected test cases.
>>>>
>>>>
>>>> Best regards
>>>> Haiyan Song
>>>> ________________________________________
>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Monday, May 28, 2018 4:54 PM
>>>> To: Song, HaiyanX
>>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> On 28/05/2018 10:22, Haiyan Song wrote:
>>>>> Hi Laurent,
>>>>>
>>>>> Yes, these tests are done on V9 patch.
>>>>
>>>> Do you plan to give this V11 a run ?
>>>>
>>>>>
>>>>>
>>>>> Best regards,
>>>>> Haiyan Song
>>>>>
>>>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>>>
>>>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>>>> tested on Intel 4s Skylake platform.
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>>>> series" while responding to the v11 header series...
>>>>>> Were these tests done on v9 or v11 ?
>>>>>>
>>>>>> Cheers,
>>>>>> Laurent.
>>>>>>
>>>>>>>
>>>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>>>> Commit id:
>>>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>>>> Benchmark suite: will-it-scale
>>>>>>> Download link:
>>>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>>>> Metrics:
>>>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>>>> THP: enable / disable
>>>>>>> nr_task: 100%
>>>>>>>
>>>>>>> 1. Regressions:
>>>>>>> a) THP enabled:
>>>>>>> testcase base change head metric
>>>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>>>
>>>>>>> b) THP disabled:
>>>>>>> testcase base change head metric
>>>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>>>
>>>>>>> 2. Improvements:
>>>>>>> a) THP enabled:
>>>>>>> testcase base change head metric
>>>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>>>
>>>>>>> b) THP disabled:
>>>>>>> testcase base change head metric
>>>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>>>
>>>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>>>
>>>>>>>
>>>>>>> Best regards
>>>>>>> Haiyan Song
>>>>>>>
>>>>>>> ________________________________________
>>>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>>>
>>>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>>>> page fault without holding the mm semaphore [1].
>>>>>>>
>>>>>>> The idea is to try to handle user space page faults without holding the
>>>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>>>> process since the page fault handler will not wait for other threads memory
>>>>>>> layout change to be done, assuming that this change is done in another part
>>>>>>> of the process's memory space. This type page fault is named speculative
>>>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>>>> is failing its processing and a classic page fault is then tried.
>>>>>>>
>>>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>>>> limiting the locking contention to these operations which are expected to
>>>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>>>> benchmark anymore.
>>>>>>>
>>>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>>>> have to be protected against parallel changes. This is done by using a per
>>>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>>>> speculative page fault in that case.
>>>>>>>
>>>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>>>> checked during the page fault are modified.
>>>>>>>
>>>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>>>> parallel change is possible at this time.
>>>>>>>
>>>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>>>> classic page fault handler will be called to handle the operation while
>>>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>>>> PTE.
>>>>>>>
>>>>>>> In pseudo code, this could be seen as:
>>>>>>> speculative_page_fault()
>>>>>>> {
>>>>>>> vma = get_vma()
>>>>>>> check vma sequence count
>>>>>>> check vma's support
>>>>>>> disable interrupt
>>>>>>> check pgd,p4d,...,pte
>>>>>>> save pmd and pte in vmf
>>>>>>> save vma sequence counter in vmf
>>>>>>> enable interrupt
>>>>>>> check vma sequence count
>>>>>>> handle_pte_fault(vma)
>>>>>>> ..
>>>>>>> page = alloc_page()
>>>>>>> pte_map_lock()
>>>>>>> disable interrupt
>>>>>>> abort if sequence counter has changed
>>>>>>> abort if pmd or pte has changed
>>>>>>> pte map and lock
>>>>>>> enable interrupt
>>>>>>> if abort
>>>>>>> free page
>>>>>>> abort
>>>>>>> ...
>>>>>>> }
>>>>>>>
>>>>>>> arch_fault_handler()
>>>>>>> {
>>>>>>> if (speculative_page_fault(&vma))
>>>>>>> goto done
>>>>>>> again:
>>>>>>> lock(mmap_sem)
>>>>>>> vma = find_vma();
>>>>>>> handle_pte_fault(vma);
>>>>>>> if retry
>>>>>>> unlock(mmap_sem)
>>>>>>> goto again;
>>>>>>> done:
>>>>>>> handle fault error
>>>>>>> }
>>>>>>>
>>>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>>>
>>>>>>> This series add a new software performance event named 'speculative-faults'
>>>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>>>> the part of the faults processed speculatively.
>>>>>>>
>>>>>>> There are some trace events introduced by this series. They allow
>>>>>>> identifying why the page faults were not processed speculatively. This
>>>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>>>> grouped in a system named 'pagefault', they are:
>>>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>>>> back.
>>>>>>>
>>>>>>> To record all the related events, the easier is to run perf with the
>>>>>>> following arguments :
>>>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>>>
>>>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>>>> page fault handled speculatively. I can be seen this way:
>>>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>>>
>>>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>>>> on x86, PowerPC and arm64.
>>>>>>>
>>>>>>> ---------------------
>>>>>>> Real Workload results
>>>>>>>
>>>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>>>> this new version should not impact the performance boost seen.
>>>>>>>
>>>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>>>> series:
>>>>>>> vanilla spf
>>>>>>> faults 89.418 101.364 +13%
>>>>>>> spf n/a 97.989
>>>>>>>
>>>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>>>> way.
>>>>>>>
>>>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>>>> it a try on an android device. He reported that the application launch time
>>>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>>>> 20%.
>>>>>>>
>>>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>>>
>>>>>>> Application 4.9 4.9+spf delta
>>>>>>> com.tencent.mm 416 389 -7%
>>>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>>>> com.tencent.mtt 455 454 0%
>>>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>>>> com.autonavi.minimap 711 701 -1%
>>>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>>>> com.immomo.momo 501 487 -3%
>>>>>>> com.tencent.peng 2145 2112 -2%
>>>>>>> com.smile.gifmaker 491 461 -6%
>>>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>>>> com.taobao.taobao 1341 1198 -11%
>>>>>>> com.baidu.searchbox 333 314 -6%
>>>>>>> com.tencent.mobileqq 394 384 -3%
>>>>>>> com.sina.weibo 907 906 0%
>>>>>>> com.youku.phone 816 731 -11%
>>>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>>>> com.UCMobile 415 411 -1%
>>>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>>>> com.tencent.qqmusic 336 329 -2%
>>>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>>>
>>>>>>> ------------------
>>>>>>> Benchmarks results
>>>>>>>
>>>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>>>> SPF is BASE + this series
>>>>>>>
>>>>>>> Kernbench:
>>>>>>> ----------
>>>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>>>> kernel (kernel is build 5 times):
>>>>>>>
>>>>>>> Average Half load -j 8
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>>>
>>>>>>> Average Optimal load -j 16
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>>>
>>>>>>>
>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>> 526743764 faults
>>>>>>> 210 spf
>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 2278 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> Very few speculative page faults were recorded as most of the processes
>>>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>>>> were created during the kernel build processing).
>>>>>>>
>>>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>>>
>>>>>>> Average Half load -j 40
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>>>
>>>>>>> Average Optimal load -j 80
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>>>
>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>> 116730856 faults
>>>>>>> 0 spf
>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 476 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>>>> there is no impact on the performance.
>>>>>>>
>>>>>>> Ebizzy:
>>>>>>> -------
>>>>>>> The test is counting the number of records per second it can manage, the
>>>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>>>> consistent result I repeated the test 100 times and measure the average
>>>>>>> result. The number is the record processes per second, the higher is the
>>>>>>> best.
>>>>>>>
>>>>>>> BASE SPF delta
>>>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>>>
>>>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>>>> 1706379 faults
>>>>>>> 1674599 spf
>>>>>>> 30588 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 363 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>>>> 1874773 faults
>>>>>>> 1461153 spf
>>>>>>> 413293 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 200 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>>>> leading the ebizzy performance boost.
>>>>>>>
>>>>>>> ------------------
>>>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>>>> and Minchan Kim, hopefully.
>>>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>>>> __do_page_fault().
>>>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>>>> instead
>>>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>>>> useless
>>>>>>> trace event pagefault:spf_pte_lock.
>>>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>>>> additional tests done didn't show a significant performance improvement.
>>>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>>>
>>>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>>>
>>>>>>>
>>>>>>> Laurent Dufour (20):
>>>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>>>> mm: make pte_unmap_same compatible with SPF
>>>>>>> mm: introduce INIT_VMA()
>>>>>>> mm: protect VMA modifications using VMA sequence count
>>>>>>> mm: protect mremap() against SPF hanlder
>>>>>>> mm: protect SPF handler against anon_vma changes
>>>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>>>> mm: introduce __vm_normal_page()
>>>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>>>> mm: protect mm_rb tree with a rwlock
>>>>>>> mm: adding speculative page fault failure trace events
>>>>>>> perf: add a speculative page fault sw event
>>>>>>> perf tools: add support for the SPF perf event
>>>>>>> mm: add speculative page fault vmstats
>>>>>>> powerpc/mm: add speculative page fault
>>>>>>>
>>>>>>> Mahendran Ganesh (2):
>>>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> arm64/mm: add speculative page fault
>>>>>>>
>>>>>>> Peter Zijlstra (4):
>>>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>>>> mm: VMA sequence count
>>>>>>> mm: provide speculative fault infrastructure
>>>>>>> x86/mm: add speculative pagefault handling
>>>>>>>
>>>>>>> arch/arm64/Kconfig | 1 +
>>>>>>> arch/arm64/mm/fault.c | 12 +
>>>>>>> arch/powerpc/Kconfig | 1 +
>>>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>>>> arch/x86/Kconfig | 1 +
>>>>>>> arch/x86/mm/fault.c | 27 +-
>>>>>>> fs/exec.c | 2 +-
>>>>>>> fs/proc/task_mmu.c | 5 +-
>>>>>>> fs/userfaultfd.c | 17 +-
>>>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>>>> include/linux/migrate.h | 4 +-
>>>>>>> include/linux/mm.h | 136 +++++++-
>>>>>>> include/linux/mm_types.h | 7 +
>>>>>>> include/linux/pagemap.h | 4 +-
>>>>>>> include/linux/rmap.h | 12 +-
>>>>>>> include/linux/swap.h | 10 +-
>>>>>>> include/linux/vm_event_item.h | 3 +
>>>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>>>> kernel/fork.c | 5 +-
>>>>>>> mm/Kconfig | 22 ++
>>>>>>> mm/huge_memory.c | 6 +-
>>>>>>> mm/hugetlb.c | 2 +
>>>>>>> mm/init-mm.c | 3 +
>>>>>>> mm/internal.h | 20 ++
>>>>>>> mm/khugepaged.c | 5 +
>>>>>>> mm/madvise.c | 6 +-
>>>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>>>> mm/mempolicy.c | 51 ++-
>>>>>>> mm/migrate.c | 6 +-
>>>>>>> mm/mlock.c | 13 +-
>>>>>>> mm/mmap.c | 229 ++++++++++---
>>>>>>> mm/mprotect.c | 4 +-
>>>>>>> mm/mremap.c | 13 +
>>>>>>> mm/nommu.c | 2 +-
>>>>>>> mm/rmap.c | 5 +-
>>>>>>> mm/swap.c | 6 +-
>>>>>>> mm/swap_state.c | 8 +-
>>>>>>> mm/vmstat.c | 5 +-
>>>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>>>> tools/perf/util/evsel.c | 1 +
>>>>>>> tools/perf/util/parse-events.c | 4 +
>>>>>>> tools/perf/util/parse-events.l | 1 +
>>>>>>> tools/perf/util/python.c | 1 +
>>>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>>>
>>>>>>> --
>>>>>>> 2.7.4
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
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^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-07-13 3:56 ` Song, HaiyanX
@ 2018-07-17 9:36 ` Laurent Dufour
2018-08-03 6:36 ` Song, HaiyanX
0 siblings, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2018-07-17 9:36 UTC (permalink / raw)
To: Song, HaiyanX
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
On 13/07/2018 05:56, Song, HaiyanX wrote:
> Hi Laurent,
Hi Haiyan,
Thanks a lot for sharing this perf reports.
I looked at them closely, and I've to admit that I was not able to found a
major difference between the base and the head report, except that
handle_pte_fault() is no more in-lined in the head one.
As expected, __handle_speculative_fault() is never traced since these tests are
dealing with file mapping, not handled in the speculative way.
When running these test did you seen a major differences in the test's result
between base and head ?
>From the number of cycles counted, the biggest difference is page_fault3 when
run with the THP enabled:
BASE HEAD Delta
page_fault2_base_thp_never 1142252426747 1065866197589 -6.69%
page_fault2_base_THP-Alwasys 1124844374523 1076312228927 -4.31%
page_fault3_base_thp_never 1099387298152 1134118402345 3.16%
page_fault3_base_THP-Always 1059370178101 853985561949 -19.39%
The very weird thing is the difference of the delta cycles reported between
thp never and thp always, because the speculative way is aborted when checking
for the vma->ops field, which is the same in both case, and the thp is never
checked. So there is no code covering differnce, on the speculative path,
between these 2 cases. This leads me to think that there are other interactions
interfering in the measure.
Looking at the perf-profile_page_fault3_*_THP-Always, the major differences at
the head of the perf report is the 92% testcase which is weirdly not reported
on the head side :
92.02% 22.33% page_fault3_processes [.] testcase
92.02% testcase
Then the base reported 37.67% for __do_page_fault() where the head reported
48.41%, but the only difference in this function, between base and head, is the
call to handle_speculative_fault(). But this is a macro checking for the fault
flags, and mm->users and then calling __handle_speculative_fault() if needed.
So this can't explain this difference, except if __handle_speculative_fault()
is inlined in __do_page_fault().
Is this the case on your build ?
Haiyan, do you still have the output of the test to check those numbers too ?
Cheers,
Laurent
> I attached the perf-profile.gz file for case page_fault2 and page_fault3. These files were captured during test the related test case.
> Please help to check on these data if it can help you to find the higher change. Thanks.
>
> File name perf-profile_page_fault2_head_THP-Always.gz, means the perf-profile result get from page_fault2
> tested for head commit (a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12) with THP_always configuration.
>
> Best regards,
> Haiyan Song
>
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Thursday, July 12, 2018 1:05 AM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> Hi Haiyan,
>
> Do you get a chance to capture some performance cycles on your system ?
> I still can't get these numbers on my hardware.
>
> Thanks,
> Laurent.
>
> On 04/07/2018 09:51, Laurent Dufour wrote:
>> On 04/07/2018 05:23, Song, HaiyanX wrote:
>>> Hi Laurent,
>>>
>>>
>>> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
>>> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
>>
>> Repeating the test only 3 times seems a bit too low to me.
>>
>> I'll focus on the higher change for the moment, but I don't have access to such
>> a hardware.
>>
>> Is possible to provide a diff between base and SPF of the performance cycles
>> measured when running page_fault3 and page_fault2 when the 20% change is detected.
>>
>> Please stay focus on the test case process to see exactly where the series is
>> impacting.
>>
>> Thanks,
>> Laurent.
>>
>>>
>>> And I did not find other high variation on test case result.
>>>
>>> a). Enable THP
>>> testcase base stddev change head stddev metric
>>> page_fault3/enable THP 10519 +- 3% -20.5% 8368 +-6% will-it-scale.per_thread_ops
>>> page_fault2/enalbe THP 8281 +- 2% -18.8% 6728 will-it-scale.per_thread_ops
>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>
>>> b). Disable THP
>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>
>>>
>>> Best regards,
>>> Haiyan Song
>>> ________________________________________
>>> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Monday, July 02, 2018 4:59 PM
>>> To: Song, HaiyanX
>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>
>>> On 11/06/2018 09:49, Song, HaiyanX wrote:
>>>> Hi Laurent,
>>>>
>>>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>>>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>>>> V9 patch serials.
>>>>
>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>>>> commit id:
>>>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>>>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>>>> Benchmark: will-it-scale
>>>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>>>
>>>> Metrics:
>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>> THP: enable / disable
>>>> nr_task:100%
>>>>
>>>> 1. Regressions:
>>>>
>>>> a). Enable THP
>>>> testcase base change head metric
>>>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>>>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>>
>>>> b). Disable THP
>>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>>
>>>> Notes: for the above values of test result, the higher is better.
>>>
>>> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
>>> get reproducible results. The results have huge variation, even on the vanilla
>>> kernel, and I can't state on any changes due to that.
>>>
>>> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
>>> measure any changes between the vanilla and the SPF patched ones:
>>>
>>> test THP enabled 4.17.0-rc4-mm1 spf delta
>>> page_fault3_threads 2697.7 2683.5 -0.53%
>>> page_fault2_threads 170660.6 169574.1 -0.64%
>>> context_switch1_threads 6915269.2 6877507.3 -0.55%
>>> context_switch1_processes 6478076.2 6529493.5 0.79%
>>> brk1 243391.2 238527.5 -2.00%
>>>
>>> Tests were run 10 times, no high variation detected.
>>>
>>> Did you see high variation on your side ? How many times the test were run to
>>> compute the average values ?
>>>
>>> Thanks,
>>> Laurent.
>>>
>>>
>>>>
>>>> 2. Improvement: not found improvement based on the selected test cases.
>>>>
>>>>
>>>> Best regards
>>>> Haiyan Song
>>>> ________________________________________
>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Monday, May 28, 2018 4:54 PM
>>>> To: Song, HaiyanX
>>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> On 28/05/2018 10:22, Haiyan Song wrote:
>>>>> Hi Laurent,
>>>>>
>>>>> Yes, these tests are done on V9 patch.
>>>>
>>>> Do you plan to give this V11 a run ?
>>>>
>>>>>
>>>>>
>>>>> Best regards,
>>>>> Haiyan Song
>>>>>
>>>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>>>
>>>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>>>> tested on Intel 4s Skylake platform.
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>>>> series" while responding to the v11 header series...
>>>>>> Were these tests done on v9 or v11 ?
>>>>>>
>>>>>> Cheers,
>>>>>> Laurent.
>>>>>>
>>>>>>>
>>>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>>>> Commit id:
>>>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>>>> Benchmark suite: will-it-scale
>>>>>>> Download link:
>>>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>>>> Metrics:
>>>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>>>> THP: enable / disable
>>>>>>> nr_task: 100%
>>>>>>>
>>>>>>> 1. Regressions:
>>>>>>> a) THP enabled:
>>>>>>> testcase base change head metric
>>>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>>>
>>>>>>> b) THP disabled:
>>>>>>> testcase base change head metric
>>>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>>>
>>>>>>> 2. Improvements:
>>>>>>> a) THP enabled:
>>>>>>> testcase base change head metric
>>>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>>>
>>>>>>> b) THP disabled:
>>>>>>> testcase base change head metric
>>>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>>>
>>>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>>>
>>>>>>>
>>>>>>> Best regards
>>>>>>> Haiyan Song
>>>>>>>
>>>>>>> ________________________________________
>>>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>>>
>>>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>>>> page fault without holding the mm semaphore [1].
>>>>>>>
>>>>>>> The idea is to try to handle user space page faults without holding the
>>>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>>>> process since the page fault handler will not wait for other threads memory
>>>>>>> layout change to be done, assuming that this change is done in another part
>>>>>>> of the process's memory space. This type page fault is named speculative
>>>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>>>> is failing its processing and a classic page fault is then tried.
>>>>>>>
>>>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>>>> limiting the locking contention to these operations which are expected to
>>>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>>>> benchmark anymore.
>>>>>>>
>>>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>>>> have to be protected against parallel changes. This is done by using a per
>>>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>>>> speculative page fault in that case.
>>>>>>>
>>>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>>>> checked during the page fault are modified.
>>>>>>>
>>>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>>>> parallel change is possible at this time.
>>>>>>>
>>>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>>>> classic page fault handler will be called to handle the operation while
>>>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>>>> PTE.
>>>>>>>
>>>>>>> In pseudo code, this could be seen as:
>>>>>>> speculative_page_fault()
>>>>>>> {
>>>>>>> vma = get_vma()
>>>>>>> check vma sequence count
>>>>>>> check vma's support
>>>>>>> disable interrupt
>>>>>>> check pgd,p4d,...,pte
>>>>>>> save pmd and pte in vmf
>>>>>>> save vma sequence counter in vmf
>>>>>>> enable interrupt
>>>>>>> check vma sequence count
>>>>>>> handle_pte_fault(vma)
>>>>>>> ..
>>>>>>> page = alloc_page()
>>>>>>> pte_map_lock()
>>>>>>> disable interrupt
>>>>>>> abort if sequence counter has changed
>>>>>>> abort if pmd or pte has changed
>>>>>>> pte map and lock
>>>>>>> enable interrupt
>>>>>>> if abort
>>>>>>> free page
>>>>>>> abort
>>>>>>> ...
>>>>>>> }
>>>>>>>
>>>>>>> arch_fault_handler()
>>>>>>> {
>>>>>>> if (speculative_page_fault(&vma))
>>>>>>> goto done
>>>>>>> again:
>>>>>>> lock(mmap_sem)
>>>>>>> vma = find_vma();
>>>>>>> handle_pte_fault(vma);
>>>>>>> if retry
>>>>>>> unlock(mmap_sem)
>>>>>>> goto again;
>>>>>>> done:
>>>>>>> handle fault error
>>>>>>> }
>>>>>>>
>>>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>>>
>>>>>>> This series add a new software performance event named 'speculative-faults'
>>>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>>>> the part of the faults processed speculatively.
>>>>>>>
>>>>>>> There are some trace events introduced by this series. They allow
>>>>>>> identifying why the page faults were not processed speculatively. This
>>>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>>>> grouped in a system named 'pagefault', they are:
>>>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>>>> back.
>>>>>>>
>>>>>>> To record all the related events, the easier is to run perf with the
>>>>>>> following arguments :
>>>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>>>
>>>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>>>> page fault handled speculatively. I can be seen this way:
>>>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>>>
>>>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>>>> on x86, PowerPC and arm64.
>>>>>>>
>>>>>>> ---------------------
>>>>>>> Real Workload results
>>>>>>>
>>>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>>>> this new version should not impact the performance boost seen.
>>>>>>>
>>>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>>>> series:
>>>>>>> vanilla spf
>>>>>>> faults 89.418 101.364 +13%
>>>>>>> spf n/a 97.989
>>>>>>>
>>>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>>>> way.
>>>>>>>
>>>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>>>> it a try on an android device. He reported that the application launch time
>>>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>>>> 20%.
>>>>>>>
>>>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>>>
>>>>>>> Application 4.9 4.9+spf delta
>>>>>>> com.tencent.mm 416 389 -7%
>>>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>>>> com.tencent.mtt 455 454 0%
>>>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>>>> com.autonavi.minimap 711 701 -1%
>>>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>>>> com.immomo.momo 501 487 -3%
>>>>>>> com.tencent.peng 2145 2112 -2%
>>>>>>> com.smile.gifmaker 491 461 -6%
>>>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>>>> com.taobao.taobao 1341 1198 -11%
>>>>>>> com.baidu.searchbox 333 314 -6%
>>>>>>> com.tencent.mobileqq 394 384 -3%
>>>>>>> com.sina.weibo 907 906 0%
>>>>>>> com.youku.phone 816 731 -11%
>>>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>>>> com.UCMobile 415 411 -1%
>>>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>>>> com.tencent.qqmusic 336 329 -2%
>>>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>>>
>>>>>>> ------------------
>>>>>>> Benchmarks results
>>>>>>>
>>>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>>>> SPF is BASE + this series
>>>>>>>
>>>>>>> Kernbench:
>>>>>>> ----------
>>>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>>>> kernel (kernel is build 5 times):
>>>>>>>
>>>>>>> Average Half load -j 8
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>>>
>>>>>>> Average Optimal load -j 16
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>>>
>>>>>>>
>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>> 526743764 faults
>>>>>>> 210 spf
>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 2278 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> Very few speculative page faults were recorded as most of the processes
>>>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>>>> were created during the kernel build processing).
>>>>>>>
>>>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>>>
>>>>>>> Average Half load -j 40
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>>>
>>>>>>> Average Optimal load -j 80
>>>>>>> Run (std deviation)
>>>>>>> BASE SPF
>>>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>>>
>>>>>>> During a run on the SPF, perf events were captured:
>>>>>>> Performance counter stats for '../kernbench -M':
>>>>>>> 116730856 faults
>>>>>>> 0 spf
>>>>>>> 3 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 476 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>>>> there is no impact on the performance.
>>>>>>>
>>>>>>> Ebizzy:
>>>>>>> -------
>>>>>>> The test is counting the number of records per second it can manage, the
>>>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>>>> consistent result I repeated the test 100 times and measure the average
>>>>>>> result. The number is the record processes per second, the higher is the
>>>>>>> best.
>>>>>>>
>>>>>>> BASE SPF delta
>>>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>>>
>>>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>>>> 1706379 faults
>>>>>>> 1674599 spf
>>>>>>> 30588 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 363 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>>>> 1874773 faults
>>>>>>> 1461153 spf
>>>>>>> 413293 pagefault:spf_vma_changed
>>>>>>> 0 pagefault:spf_vma_noanon
>>>>>>> 200 pagefault:spf_vma_notsup
>>>>>>> 0 pagefault:spf_vma_access
>>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>>
>>>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>>>> leading the ebizzy performance boost.
>>>>>>>
>>>>>>> ------------------
>>>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>>>> and Minchan Kim, hopefully.
>>>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>>>> __do_page_fault().
>>>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>>>> instead
>>>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>>>> useless
>>>>>>> trace event pagefault:spf_pte_lock.
>>>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>>>> additional tests done didn't show a significant performance improvement.
>>>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>>>
>>>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>>>
>>>>>>>
>>>>>>> Laurent Dufour (20):
>>>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>>>> mm: make pte_unmap_same compatible with SPF
>>>>>>> mm: introduce INIT_VMA()
>>>>>>> mm: protect VMA modifications using VMA sequence count
>>>>>>> mm: protect mremap() against SPF hanlder
>>>>>>> mm: protect SPF handler against anon_vma changes
>>>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>>>> mm: introduce __vm_normal_page()
>>>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>>>> mm: protect mm_rb tree with a rwlock
>>>>>>> mm: adding speculative page fault failure trace events
>>>>>>> perf: add a speculative page fault sw event
>>>>>>> perf tools: add support for the SPF perf event
>>>>>>> mm: add speculative page fault vmstats
>>>>>>> powerpc/mm: add speculative page fault
>>>>>>>
>>>>>>> Mahendran Ganesh (2):
>>>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>>> arm64/mm: add speculative page fault
>>>>>>>
>>>>>>> Peter Zijlstra (4):
>>>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>>>> mm: VMA sequence count
>>>>>>> mm: provide speculative fault infrastructure
>>>>>>> x86/mm: add speculative pagefault handling
>>>>>>>
>>>>>>> arch/arm64/Kconfig | 1 +
>>>>>>> arch/arm64/mm/fault.c | 12 +
>>>>>>> arch/powerpc/Kconfig | 1 +
>>>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>>>> arch/x86/Kconfig | 1 +
>>>>>>> arch/x86/mm/fault.c | 27 +-
>>>>>>> fs/exec.c | 2 +-
>>>>>>> fs/proc/task_mmu.c | 5 +-
>>>>>>> fs/userfaultfd.c | 17 +-
>>>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>>>> include/linux/migrate.h | 4 +-
>>>>>>> include/linux/mm.h | 136 +++++++-
>>>>>>> include/linux/mm_types.h | 7 +
>>>>>>> include/linux/pagemap.h | 4 +-
>>>>>>> include/linux/rmap.h | 12 +-
>>>>>>> include/linux/swap.h | 10 +-
>>>>>>> include/linux/vm_event_item.h | 3 +
>>>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>>>> kernel/fork.c | 5 +-
>>>>>>> mm/Kconfig | 22 ++
>>>>>>> mm/huge_memory.c | 6 +-
>>>>>>> mm/hugetlb.c | 2 +
>>>>>>> mm/init-mm.c | 3 +
>>>>>>> mm/internal.h | 20 ++
>>>>>>> mm/khugepaged.c | 5 +
>>>>>>> mm/madvise.c | 6 +-
>>>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>>>> mm/mempolicy.c | 51 ++-
>>>>>>> mm/migrate.c | 6 +-
>>>>>>> mm/mlock.c | 13 +-
>>>>>>> mm/mmap.c | 229 ++++++++++---
>>>>>>> mm/mprotect.c | 4 +-
>>>>>>> mm/mremap.c | 13 +
>>>>>>> mm/nommu.c | 2 +-
>>>>>>> mm/rmap.c | 5 +-
>>>>>>> mm/swap.c | 6 +-
>>>>>>> mm/swap_state.c | 8 +-
>>>>>>> mm/vmstat.c | 5 +-
>>>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>>>> tools/perf/util/evsel.c | 1 +
>>>>>>> tools/perf/util/parse-events.c | 4 +
>>>>>>> tools/perf/util/parse-events.l | 1 +
>>>>>>> tools/perf/util/python.c | 1 +
>>>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>>>
>>>>>>> --
>>>>>>> 2.7.4
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-07-11 17:05 ` Laurent Dufour
@ 2018-07-13 3:56 ` Song, HaiyanX
2018-07-17 9:36 ` Laurent Dufour
0 siblings, 1 reply; 46+ messages in thread
From: Song, HaiyanX @ 2018-07-13 3:56 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
[-- Attachment #1: Type: text/plain, Size: 37281 bytes --]
Hi Laurent,
I attached the perf-profile.gz file for case page_fault2 and page_fault3. These files were captured during test the related test case.
Please help to check on these data if it can help you to find the higher change. Thanks.
File name perf-profile_page_fault2_head_THP-Always.gz, means the perf-profile result get from page_fault2
tested for head commit (a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12) with THP_always configuration.
Best regards,
Haiyan Song
________________________________________
From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
Sent: Thursday, July 12, 2018 1:05 AM
To: Song, HaiyanX
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: Re: [PATCH v11 00/26] Speculative page faults
Hi Haiyan,
Do you get a chance to capture some performance cycles on your system ?
I still can't get these numbers on my hardware.
Thanks,
Laurent.
On 04/07/2018 09:51, Laurent Dufour wrote:
> On 04/07/2018 05:23, Song, HaiyanX wrote:
>> Hi Laurent,
>>
>>
>> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
>> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
>
> Repeating the test only 3 times seems a bit too low to me.
>
> I'll focus on the higher change for the moment, but I don't have access to such
> a hardware.
>
> Is possible to provide a diff between base and SPF of the performance cycles
> measured when running page_fault3 and page_fault2 when the 20% change is detected.
>
> Please stay focus on the test case process to see exactly where the series is
> impacting.
>
> Thanks,
> Laurent.
>
>>
>> And I did not find other high variation on test case result.
>>
>> a). Enable THP
>> testcase base stddev change head stddev metric
>> page_fault3/enable THP 10519 ± 3% -20.5% 8368 ±6% will-it-scale.per_thread_ops
>> page_fault2/enalbe THP 8281 ± 2% -18.8% 6728 will-it-scale.per_thread_ops
>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>
>> b). Disable THP
>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>
>>
>> Best regards,
>> Haiyan Song
>> ________________________________________
>> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
>> Sent: Monday, July 02, 2018 4:59 PM
>> To: Song, HaiyanX
>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>
>> On 11/06/2018 09:49, Song, HaiyanX wrote:
>>> Hi Laurent,
>>>
>>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>>> V9 patch serials.
>>>
>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>>> commit id:
>>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>>> Benchmark: will-it-scale
>>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>>
>>> Metrics:
>>> will-it-scale.per_process_ops=processes/nr_cpu
>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>> THP: enable / disable
>>> nr_task:100%
>>>
>>> 1. Regressions:
>>>
>>> a). Enable THP
>>> testcase base change head metric
>>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>
>>> b). Disable THP
>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>
>>> Notes: for the above values of test result, the higher is better.
>>
>> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
>> get reproducible results. The results have huge variation, even on the vanilla
>> kernel, and I can't state on any changes due to that.
>>
>> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
>> measure any changes between the vanilla and the SPF patched ones:
>>
>> test THP enabled 4.17.0-rc4-mm1 spf delta
>> page_fault3_threads 2697.7 2683.5 -0.53%
>> page_fault2_threads 170660.6 169574.1 -0.64%
>> context_switch1_threads 6915269.2 6877507.3 -0.55%
>> context_switch1_processes 6478076.2 6529493.5 0.79%
>> brk1 243391.2 238527.5 -2.00%
>>
>> Tests were run 10 times, no high variation detected.
>>
>> Did you see high variation on your side ? How many times the test were run to
>> compute the average values ?
>>
>> Thanks,
>> Laurent.
>>
>>
>>>
>>> 2. Improvement: not found improvement based on the selected test cases.
>>>
>>>
>>> Best regards
>>> Haiyan Song
>>> ________________________________________
>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Monday, May 28, 2018 4:54 PM
>>> To: Song, HaiyanX
>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>
>>> On 28/05/2018 10:22, Haiyan Song wrote:
>>>> Hi Laurent,
>>>>
>>>> Yes, these tests are done on V9 patch.
>>>
>>> Do you plan to give this V11 a run ?
>>>
>>>>
>>>>
>>>> Best regards,
>>>> Haiyan Song
>>>>
>>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>>
>>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>>> tested on Intel 4s Skylake platform.
>>>>>
>>>>> Hi,
>>>>>
>>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>>> series" while responding to the v11 header series...
>>>>> Were these tests done on v9 or v11 ?
>>>>>
>>>>> Cheers,
>>>>> Laurent.
>>>>>
>>>>>>
>>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>>> Commit id:
>>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>>> Benchmark suite: will-it-scale
>>>>>> Download link:
>>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>>> Metrics:
>>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>>> THP: enable / disable
>>>>>> nr_task: 100%
>>>>>>
>>>>>> 1. Regressions:
>>>>>> a) THP enabled:
>>>>>> testcase base change head metric
>>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>>
>>>>>> b) THP disabled:
>>>>>> testcase base change head metric
>>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>>
>>>>>> 2. Improvements:
>>>>>> a) THP enabled:
>>>>>> testcase base change head metric
>>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>>
>>>>>> b) THP disabled:
>>>>>> testcase base change head metric
>>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>>
>>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>>
>>>>>>
>>>>>> Best regards
>>>>>> Haiyan Song
>>>>>>
>>>>>> ________________________________________
>>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>>
>>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>>> page fault without holding the mm semaphore [1].
>>>>>>
>>>>>> The idea is to try to handle user space page faults without holding the
>>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>>> process since the page fault handler will not wait for other threads memory
>>>>>> layout change to be done, assuming that this change is done in another part
>>>>>> of the process's memory space. This type page fault is named speculative
>>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>>> is failing its processing and a classic page fault is then tried.
>>>>>>
>>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>>> limiting the locking contention to these operations which are expected to
>>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>>> benchmark anymore.
>>>>>>
>>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>>> have to be protected against parallel changes. This is done by using a per
>>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>>> speculative page fault in that case.
>>>>>>
>>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>>> checked during the page fault are modified.
>>>>>>
>>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>>> parallel change is possible at this time.
>>>>>>
>>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>>> classic page fault handler will be called to handle the operation while
>>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>>> PTE.
>>>>>>
>>>>>> In pseudo code, this could be seen as:
>>>>>> speculative_page_fault()
>>>>>> {
>>>>>> vma = get_vma()
>>>>>> check vma sequence count
>>>>>> check vma's support
>>>>>> disable interrupt
>>>>>> check pgd,p4d,...,pte
>>>>>> save pmd and pte in vmf
>>>>>> save vma sequence counter in vmf
>>>>>> enable interrupt
>>>>>> check vma sequence count
>>>>>> handle_pte_fault(vma)
>>>>>> ..
>>>>>> page = alloc_page()
>>>>>> pte_map_lock()
>>>>>> disable interrupt
>>>>>> abort if sequence counter has changed
>>>>>> abort if pmd or pte has changed
>>>>>> pte map and lock
>>>>>> enable interrupt
>>>>>> if abort
>>>>>> free page
>>>>>> abort
>>>>>> ...
>>>>>> }
>>>>>>
>>>>>> arch_fault_handler()
>>>>>> {
>>>>>> if (speculative_page_fault(&vma))
>>>>>> goto done
>>>>>> again:
>>>>>> lock(mmap_sem)
>>>>>> vma = find_vma();
>>>>>> handle_pte_fault(vma);
>>>>>> if retry
>>>>>> unlock(mmap_sem)
>>>>>> goto again;
>>>>>> done:
>>>>>> handle fault error
>>>>>> }
>>>>>>
>>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>>
>>>>>> This series add a new software performance event named 'speculative-faults'
>>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>>> the part of the faults processed speculatively.
>>>>>>
>>>>>> There are some trace events introduced by this series. They allow
>>>>>> identifying why the page faults were not processed speculatively. This
>>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>>> grouped in a system named 'pagefault', they are:
>>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>>> back.
>>>>>>
>>>>>> To record all the related events, the easier is to run perf with the
>>>>>> following arguments :
>>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>>
>>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>>> page fault handled speculatively. I can be seen this way:
>>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>>
>>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>>> on x86, PowerPC and arm64.
>>>>>>
>>>>>> ---------------------
>>>>>> Real Workload results
>>>>>>
>>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>>> this new version should not impact the performance boost seen.
>>>>>>
>>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>>> series:
>>>>>> vanilla spf
>>>>>> faults 89.418 101.364 +13%
>>>>>> spf n/a 97.989
>>>>>>
>>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>>> way.
>>>>>>
>>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>>> it a try on an android device. He reported that the application launch time
>>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>>> 20%.
>>>>>>
>>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>>
>>>>>> Application 4.9 4.9+spf delta
>>>>>> com.tencent.mm 416 389 -7%
>>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>>> com.tencent.mtt 455 454 0%
>>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>>> com.autonavi.minimap 711 701 -1%
>>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>>> com.immomo.momo 501 487 -3%
>>>>>> com.tencent.peng 2145 2112 -2%
>>>>>> com.smile.gifmaker 491 461 -6%
>>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>>> com.taobao.taobao 1341 1198 -11%
>>>>>> com.baidu.searchbox 333 314 -6%
>>>>>> com.tencent.mobileqq 394 384 -3%
>>>>>> com.sina.weibo 907 906 0%
>>>>>> com.youku.phone 816 731 -11%
>>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>>> com.UCMobile 415 411 -1%
>>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>>> com.tencent.qqmusic 336 329 -2%
>>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>>
>>>>>> ------------------
>>>>>> Benchmarks results
>>>>>>
>>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>>> SPF is BASE + this series
>>>>>>
>>>>>> Kernbench:
>>>>>> ----------
>>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>>> kernel (kernel is build 5 times):
>>>>>>
>>>>>> Average Half load -j 8
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>>
>>>>>> Average Optimal load -j 16
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>>
>>>>>>
>>>>>> During a run on the SPF, perf events were captured:
>>>>>> Performance counter stats for '../kernbench -M':
>>>>>> 526743764 faults
>>>>>> 210 spf
>>>>>> 3 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 2278 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> Very few speculative page faults were recorded as most of the processes
>>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>>> were created during the kernel build processing).
>>>>>>
>>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>>
>>>>>> Average Half load -j 40
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>>
>>>>>> Average Optimal load -j 80
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>>
>>>>>> During a run on the SPF, perf events were captured:
>>>>>> Performance counter stats for '../kernbench -M':
>>>>>> 116730856 faults
>>>>>> 0 spf
>>>>>> 3 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 476 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>>> there is no impact on the performance.
>>>>>>
>>>>>> Ebizzy:
>>>>>> -------
>>>>>> The test is counting the number of records per second it can manage, the
>>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>>> consistent result I repeated the test 100 times and measure the average
>>>>>> result. The number is the record processes per second, the higher is the
>>>>>> best.
>>>>>>
>>>>>> BASE SPF delta
>>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>>
>>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>>> 1706379 faults
>>>>>> 1674599 spf
>>>>>> 30588 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 363 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>>> 1874773 faults
>>>>>> 1461153 spf
>>>>>> 413293 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 200 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>>> leading the ebizzy performance boost.
>>>>>>
>>>>>> ------------------
>>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>>> and Minchan Kim, hopefully.
>>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>>> __do_page_fault().
>>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>>> instead
>>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>>> useless
>>>>>> trace event pagefault:spf_pte_lock.
>>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>>> additional tests done didn't show a significant performance improvement.
>>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>>
>>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>>
>>>>>>
>>>>>> Laurent Dufour (20):
>>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>>> mm: make pte_unmap_same compatible with SPF
>>>>>> mm: introduce INIT_VMA()
>>>>>> mm: protect VMA modifications using VMA sequence count
>>>>>> mm: protect mremap() against SPF hanlder
>>>>>> mm: protect SPF handler against anon_vma changes
>>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>>> mm: introduce __vm_normal_page()
>>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>>> mm: protect mm_rb tree with a rwlock
>>>>>> mm: adding speculative page fault failure trace events
>>>>>> perf: add a speculative page fault sw event
>>>>>> perf tools: add support for the SPF perf event
>>>>>> mm: add speculative page fault vmstats
>>>>>> powerpc/mm: add speculative page fault
>>>>>>
>>>>>> Mahendran Ganesh (2):
>>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>> arm64/mm: add speculative page fault
>>>>>>
>>>>>> Peter Zijlstra (4):
>>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>>> mm: VMA sequence count
>>>>>> mm: provide speculative fault infrastructure
>>>>>> x86/mm: add speculative pagefault handling
>>>>>>
>>>>>> arch/arm64/Kconfig | 1 +
>>>>>> arch/arm64/mm/fault.c | 12 +
>>>>>> arch/powerpc/Kconfig | 1 +
>>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>>> arch/x86/Kconfig | 1 +
>>>>>> arch/x86/mm/fault.c | 27 +-
>>>>>> fs/exec.c | 2 +-
>>>>>> fs/proc/task_mmu.c | 5 +-
>>>>>> fs/userfaultfd.c | 17 +-
>>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>>> include/linux/migrate.h | 4 +-
>>>>>> include/linux/mm.h | 136 +++++++-
>>>>>> include/linux/mm_types.h | 7 +
>>>>>> include/linux/pagemap.h | 4 +-
>>>>>> include/linux/rmap.h | 12 +-
>>>>>> include/linux/swap.h | 10 +-
>>>>>> include/linux/vm_event_item.h | 3 +
>>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>>> kernel/fork.c | 5 +-
>>>>>> mm/Kconfig | 22 ++
>>>>>> mm/huge_memory.c | 6 +-
>>>>>> mm/hugetlb.c | 2 +
>>>>>> mm/init-mm.c | 3 +
>>>>>> mm/internal.h | 20 ++
>>>>>> mm/khugepaged.c | 5 +
>>>>>> mm/madvise.c | 6 +-
>>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>>> mm/mempolicy.c | 51 ++-
>>>>>> mm/migrate.c | 6 +-
>>>>>> mm/mlock.c | 13 +-
>>>>>> mm/mmap.c | 229 ++++++++++---
>>>>>> mm/mprotect.c | 4 +-
>>>>>> mm/mremap.c | 13 +
>>>>>> mm/nommu.c | 2 +-
>>>>>> mm/rmap.c | 5 +-
>>>>>> mm/swap.c | 6 +-
>>>>>> mm/swap_state.c | 8 +-
>>>>>> mm/vmstat.c | 5 +-
>>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>>> tools/perf/util/evsel.c | 1 +
>>>>>> tools/perf/util/parse-events.c | 4 +
>>>>>> tools/perf/util/parse-events.l | 1 +
>>>>>> tools/perf/util/python.c | 1 +
>>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>>
>>>>>> --
>>>>>> 2.7.4
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>>
>
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^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-07-04 7:51 ` Laurent Dufour
@ 2018-07-11 17:05 ` Laurent Dufour
2018-07-13 3:56 ` Song, HaiyanX
0 siblings, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2018-07-11 17:05 UTC (permalink / raw)
To: Song, HaiyanX
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
Hi Haiyan,
Do you get a chance to capture some performance cycles on your system ?
I still can't get these numbers on my hardware.
Thanks,
Laurent.
On 04/07/2018 09:51, Laurent Dufour wrote:
> On 04/07/2018 05:23, Song, HaiyanX wrote:
>> Hi Laurent,
>>
>>
>> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
>> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
>
> Repeating the test only 3 times seems a bit too low to me.
>
> I'll focus on the higher change for the moment, but I don't have access to such
> a hardware.
>
> Is possible to provide a diff between base and SPF of the performance cycles
> measured when running page_fault3 and page_fault2 when the 20% change is detected.
>
> Please stay focus on the test case process to see exactly where the series is
> impacting.
>
> Thanks,
> Laurent.
>
>>
>> And I did not find other high variation on test case result.
>>
>> a). Enable THP
>> testcase base stddev change head stddev metric
>> page_fault3/enable THP 10519 A+- 3% -20.5% 8368 A+-6% will-it-scale.per_thread_ops
>> page_fault2/enalbe THP 8281 A+- 2% -18.8% 6728 will-it-scale.per_thread_ops
>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>
>> b). Disable THP
>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>
>>
>> Best regards,
>> Haiyan Song
>> ________________________________________
>> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
>> Sent: Monday, July 02, 2018 4:59 PM
>> To: Song, HaiyanX
>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>
>> On 11/06/2018 09:49, Song, HaiyanX wrote:
>>> Hi Laurent,
>>>
>>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>>> V9 patch serials.
>>>
>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>>> commit id:
>>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>>> Benchmark: will-it-scale
>>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>>
>>> Metrics:
>>> will-it-scale.per_process_ops=processes/nr_cpu
>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>> THP: enable / disable
>>> nr_task:100%
>>>
>>> 1. Regressions:
>>>
>>> a). Enable THP
>>> testcase base change head metric
>>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>>
>>> b). Disable THP
>>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>>
>>> Notes: for the above values of test result, the higher is better.
>>
>> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
>> get reproducible results. The results have huge variation, even on the vanilla
>> kernel, and I can't state on any changes due to that.
>>
>> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
>> measure any changes between the vanilla and the SPF patched ones:
>>
>> test THP enabled 4.17.0-rc4-mm1 spf delta
>> page_fault3_threads 2697.7 2683.5 -0.53%
>> page_fault2_threads 170660.6 169574.1 -0.64%
>> context_switch1_threads 6915269.2 6877507.3 -0.55%
>> context_switch1_processes 6478076.2 6529493.5 0.79%
>> brk1 243391.2 238527.5 -2.00%
>>
>> Tests were run 10 times, no high variation detected.
>>
>> Did you see high variation on your side ? How many times the test were run to
>> compute the average values ?
>>
>> Thanks,
>> Laurent.
>>
>>
>>>
>>> 2. Improvement: not found improvement based on the selected test cases.
>>>
>>>
>>> Best regards
>>> Haiyan Song
>>> ________________________________________
>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Monday, May 28, 2018 4:54 PM
>>> To: Song, HaiyanX
>>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>>
>>> On 28/05/2018 10:22, Haiyan Song wrote:
>>>> Hi Laurent,
>>>>
>>>> Yes, these tests are done on V9 patch.
>>>
>>> Do you plan to give this V11 a run ?
>>>
>>>>
>>>>
>>>> Best regards,
>>>> Haiyan Song
>>>>
>>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>>
>>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>>> tested on Intel 4s Skylake platform.
>>>>>
>>>>> Hi,
>>>>>
>>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>>> series" while responding to the v11 header series...
>>>>> Were these tests done on v9 or v11 ?
>>>>>
>>>>> Cheers,
>>>>> Laurent.
>>>>>
>>>>>>
>>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>>> Commit id:
>>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>>> Benchmark suite: will-it-scale
>>>>>> Download link:
>>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>>> Metrics:
>>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>>> THP: enable / disable
>>>>>> nr_task: 100%
>>>>>>
>>>>>> 1. Regressions:
>>>>>> a) THP enabled:
>>>>>> testcase base change head metric
>>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>>
>>>>>> b) THP disabled:
>>>>>> testcase base change head metric
>>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>>
>>>>>> 2. Improvements:
>>>>>> a) THP enabled:
>>>>>> testcase base change head metric
>>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>>
>>>>>> b) THP disabled:
>>>>>> testcase base change head metric
>>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>>
>>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>>
>>>>>>
>>>>>> Best regards
>>>>>> Haiyan Song
>>>>>>
>>>>>> ________________________________________
>>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>>
>>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>>> page fault without holding the mm semaphore [1].
>>>>>>
>>>>>> The idea is to try to handle user space page faults without holding the
>>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>>> process since the page fault handler will not wait for other threads memory
>>>>>> layout change to be done, assuming that this change is done in another part
>>>>>> of the process's memory space. This type page fault is named speculative
>>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>>> is failing its processing and a classic page fault is then tried.
>>>>>>
>>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>>> limiting the locking contention to these operations which are expected to
>>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>>> benchmark anymore.
>>>>>>
>>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>>> have to be protected against parallel changes. This is done by using a per
>>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>>> speculative page fault in that case.
>>>>>>
>>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>>> checked during the page fault are modified.
>>>>>>
>>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>>> parallel change is possible at this time.
>>>>>>
>>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>>> classic page fault handler will be called to handle the operation while
>>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>>> PTE.
>>>>>>
>>>>>> In pseudo code, this could be seen as:
>>>>>> speculative_page_fault()
>>>>>> {
>>>>>> vma = get_vma()
>>>>>> check vma sequence count
>>>>>> check vma's support
>>>>>> disable interrupt
>>>>>> check pgd,p4d,...,pte
>>>>>> save pmd and pte in vmf
>>>>>> save vma sequence counter in vmf
>>>>>> enable interrupt
>>>>>> check vma sequence count
>>>>>> handle_pte_fault(vma)
>>>>>> ..
>>>>>> page = alloc_page()
>>>>>> pte_map_lock()
>>>>>> disable interrupt
>>>>>> abort if sequence counter has changed
>>>>>> abort if pmd or pte has changed
>>>>>> pte map and lock
>>>>>> enable interrupt
>>>>>> if abort
>>>>>> free page
>>>>>> abort
>>>>>> ...
>>>>>> }
>>>>>>
>>>>>> arch_fault_handler()
>>>>>> {
>>>>>> if (speculative_page_fault(&vma))
>>>>>> goto done
>>>>>> again:
>>>>>> lock(mmap_sem)
>>>>>> vma = find_vma();
>>>>>> handle_pte_fault(vma);
>>>>>> if retry
>>>>>> unlock(mmap_sem)
>>>>>> goto again;
>>>>>> done:
>>>>>> handle fault error
>>>>>> }
>>>>>>
>>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>>
>>>>>> This series add a new software performance event named 'speculative-faults'
>>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>>> the part of the faults processed speculatively.
>>>>>>
>>>>>> There are some trace events introduced by this series. They allow
>>>>>> identifying why the page faults were not processed speculatively. This
>>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>>> grouped in a system named 'pagefault', they are:
>>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>>> back.
>>>>>>
>>>>>> To record all the related events, the easier is to run perf with the
>>>>>> following arguments :
>>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>>
>>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>>> page fault handled speculatively. I can be seen this way:
>>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>>
>>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>>> on x86, PowerPC and arm64.
>>>>>>
>>>>>> ---------------------
>>>>>> Real Workload results
>>>>>>
>>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>>> this new version should not impact the performance boost seen.
>>>>>>
>>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>>> series:
>>>>>> vanilla spf
>>>>>> faults 89.418 101.364 +13%
>>>>>> spf n/a 97.989
>>>>>>
>>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>>> way.
>>>>>>
>>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>>> it a try on an android device. He reported that the application launch time
>>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>>> 20%.
>>>>>>
>>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>>
>>>>>> Application 4.9 4.9+spf delta
>>>>>> com.tencent.mm 416 389 -7%
>>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>>> com.tencent.mtt 455 454 0%
>>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>>> com.autonavi.minimap 711 701 -1%
>>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>>> com.immomo.momo 501 487 -3%
>>>>>> com.tencent.peng 2145 2112 -2%
>>>>>> com.smile.gifmaker 491 461 -6%
>>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>>> com.taobao.taobao 1341 1198 -11%
>>>>>> com.baidu.searchbox 333 314 -6%
>>>>>> com.tencent.mobileqq 394 384 -3%
>>>>>> com.sina.weibo 907 906 0%
>>>>>> com.youku.phone 816 731 -11%
>>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>>> com.UCMobile 415 411 -1%
>>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>>> com.tencent.qqmusic 336 329 -2%
>>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>>
>>>>>> ------------------
>>>>>> Benchmarks results
>>>>>>
>>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>>> SPF is BASE + this series
>>>>>>
>>>>>> Kernbench:
>>>>>> ----------
>>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>>> kernel (kernel is build 5 times):
>>>>>>
>>>>>> Average Half load -j 8
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>>
>>>>>> Average Optimal load -j 16
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>>
>>>>>>
>>>>>> During a run on the SPF, perf events were captured:
>>>>>> Performance counter stats for '../kernbench -M':
>>>>>> 526743764 faults
>>>>>> 210 spf
>>>>>> 3 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 2278 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> Very few speculative page faults were recorded as most of the processes
>>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>>> were created during the kernel build processing).
>>>>>>
>>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>>
>>>>>> Average Half load -j 40
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>>
>>>>>> Average Optimal load -j 80
>>>>>> Run (std deviation)
>>>>>> BASE SPF
>>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>>
>>>>>> During a run on the SPF, perf events were captured:
>>>>>> Performance counter stats for '../kernbench -M':
>>>>>> 116730856 faults
>>>>>> 0 spf
>>>>>> 3 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 476 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>>> there is no impact on the performance.
>>>>>>
>>>>>> Ebizzy:
>>>>>> -------
>>>>>> The test is counting the number of records per second it can manage, the
>>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>>> consistent result I repeated the test 100 times and measure the average
>>>>>> result. The number is the record processes per second, the higher is the
>>>>>> best.
>>>>>>
>>>>>> BASE SPF delta
>>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>>
>>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>>> 1706379 faults
>>>>>> 1674599 spf
>>>>>> 30588 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 363 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>>> 1874773 faults
>>>>>> 1461153 spf
>>>>>> 413293 pagefault:spf_vma_changed
>>>>>> 0 pagefault:spf_vma_noanon
>>>>>> 200 pagefault:spf_vma_notsup
>>>>>> 0 pagefault:spf_vma_access
>>>>>> 0 pagefault:spf_pmd_changed
>>>>>>
>>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>>> leading the ebizzy performance boost.
>>>>>>
>>>>>> ------------------
>>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>>> and Minchan Kim, hopefully.
>>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>>> __do_page_fault().
>>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>>> instead
>>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>>> useless
>>>>>> trace event pagefault:spf_pte_lock.
>>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>>> additional tests done didn't show a significant performance improvement.
>>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>>
>>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>>
>>>>>>
>>>>>> Laurent Dufour (20):
>>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>>> mm: make pte_unmap_same compatible with SPF
>>>>>> mm: introduce INIT_VMA()
>>>>>> mm: protect VMA modifications using VMA sequence count
>>>>>> mm: protect mremap() against SPF hanlder
>>>>>> mm: protect SPF handler against anon_vma changes
>>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>>> mm: introduce __vm_normal_page()
>>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>>> mm: protect mm_rb tree with a rwlock
>>>>>> mm: adding speculative page fault failure trace events
>>>>>> perf: add a speculative page fault sw event
>>>>>> perf tools: add support for the SPF perf event
>>>>>> mm: add speculative page fault vmstats
>>>>>> powerpc/mm: add speculative page fault
>>>>>>
>>>>>> Mahendran Ganesh (2):
>>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>>> arm64/mm: add speculative page fault
>>>>>>
>>>>>> Peter Zijlstra (4):
>>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>>> mm: VMA sequence count
>>>>>> mm: provide speculative fault infrastructure
>>>>>> x86/mm: add speculative pagefault handling
>>>>>>
>>>>>> arch/arm64/Kconfig | 1 +
>>>>>> arch/arm64/mm/fault.c | 12 +
>>>>>> arch/powerpc/Kconfig | 1 +
>>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>>> arch/x86/Kconfig | 1 +
>>>>>> arch/x86/mm/fault.c | 27 +-
>>>>>> fs/exec.c | 2 +-
>>>>>> fs/proc/task_mmu.c | 5 +-
>>>>>> fs/userfaultfd.c | 17 +-
>>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>>> include/linux/migrate.h | 4 +-
>>>>>> include/linux/mm.h | 136 +++++++-
>>>>>> include/linux/mm_types.h | 7 +
>>>>>> include/linux/pagemap.h | 4 +-
>>>>>> include/linux/rmap.h | 12 +-
>>>>>> include/linux/swap.h | 10 +-
>>>>>> include/linux/vm_event_item.h | 3 +
>>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>>> kernel/fork.c | 5 +-
>>>>>> mm/Kconfig | 22 ++
>>>>>> mm/huge_memory.c | 6 +-
>>>>>> mm/hugetlb.c | 2 +
>>>>>> mm/init-mm.c | 3 +
>>>>>> mm/internal.h | 20 ++
>>>>>> mm/khugepaged.c | 5 +
>>>>>> mm/madvise.c | 6 +-
>>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>>> mm/mempolicy.c | 51 ++-
>>>>>> mm/migrate.c | 6 +-
>>>>>> mm/mlock.c | 13 +-
>>>>>> mm/mmap.c | 229 ++++++++++---
>>>>>> mm/mprotect.c | 4 +-
>>>>>> mm/mremap.c | 13 +
>>>>>> mm/nommu.c | 2 +-
>>>>>> mm/rmap.c | 5 +-
>>>>>> mm/swap.c | 6 +-
>>>>>> mm/swap_state.c | 8 +-
>>>>>> mm/vmstat.c | 5 +-
>>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>>> tools/perf/util/evsel.c | 1 +
>>>>>> tools/perf/util/parse-events.c | 4 +
>>>>>> tools/perf/util/parse-events.l | 1 +
>>>>>> tools/perf/util/python.c | 1 +
>>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>>
>>>>>> --
>>>>>> 2.7.4
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-07-04 3:23 ` Song, HaiyanX
@ 2018-07-04 7:51 ` Laurent Dufour
2018-07-11 17:05 ` Laurent Dufour
0 siblings, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2018-07-04 7:51 UTC (permalink / raw)
To: Song, HaiyanX
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
On 04/07/2018 05:23, Song, HaiyanX wrote:
> Hi Laurent,
>
>
> For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
> I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
Repeating the test only 3 times seems a bit too low to me.
I'll focus on the higher change for the moment, but I don't have access to such
a hardware.
Is possible to provide a diff between base and SPF of the performance cycles
measured when running page_fault3 and page_fault2 when the 20% change is detected.
Please stay focus on the test case process to see exactly where the series is
impacting.
Thanks,
Laurent.
>
> And I did not find other high variation on test case result.
>
> a). Enable THP
> testcase base stddev change head stddev metric
> page_fault3/enable THP 10519 A+- 3% -20.5% 8368 A+-6% will-it-scale.per_thread_ops
> page_fault2/enalbe THP 8281 A+- 2% -18.8% 6728 will-it-scale.per_thread_ops
> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>
> b). Disable THP
> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>
>
> Best regards,
> Haiyan Song
> ________________________________________
> From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Monday, July 02, 2018 4:59 PM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> On 11/06/2018 09:49, Song, HaiyanX wrote:
>> Hi Laurent,
>>
>> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
>> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
>> V9 patch serials.
>>
>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
>> commit id:
>> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
>> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
>> Benchmark: will-it-scale
>> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>>
>> Metrics:
>> will-it-scale.per_process_ops=processes/nr_cpu
>> will-it-scale.per_thread_ops=threads/nr_cpu
>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>> THP: enable / disable
>> nr_task:100%
>>
>> 1. Regressions:
>>
>> a). Enable THP
>> testcase base change head metric
>> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
>> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
>> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
>> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
>> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>>
>> b). Disable THP
>> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
>> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
>> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
>> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
>> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
>> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
>> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>>
>> Notes: for the above values of test result, the higher is better.
>
> I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
> get reproducible results. The results have huge variation, even on the vanilla
> kernel, and I can't state on any changes due to that.
>
> I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
> measure any changes between the vanilla and the SPF patched ones:
>
> test THP enabled 4.17.0-rc4-mm1 spf delta
> page_fault3_threads 2697.7 2683.5 -0.53%
> page_fault2_threads 170660.6 169574.1 -0.64%
> context_switch1_threads 6915269.2 6877507.3 -0.55%
> context_switch1_processes 6478076.2 6529493.5 0.79%
> brk1 243391.2 238527.5 -2.00%
>
> Tests were run 10 times, no high variation detected.
>
> Did you see high variation on your side ? How many times the test were run to
> compute the average values ?
>
> Thanks,
> Laurent.
>
>
>>
>> 2. Improvement: not found improvement based on the selected test cases.
>>
>>
>> Best regards
>> Haiyan Song
>> ________________________________________
>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>> Sent: Monday, May 28, 2018 4:54 PM
>> To: Song, HaiyanX
>> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>> Subject: Re: [PATCH v11 00/26] Speculative page faults
>>
>> On 28/05/2018 10:22, Haiyan Song wrote:
>>> Hi Laurent,
>>>
>>> Yes, these tests are done on V9 patch.
>>
>> Do you plan to give this V11 a run ?
>>
>>>
>>>
>>> Best regards,
>>> Haiyan Song
>>>
>>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>>
>>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>>> tested on Intel 4s Skylake platform.
>>>>
>>>> Hi,
>>>>
>>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>>> series" while responding to the v11 header series...
>>>> Were these tests done on v9 or v11 ?
>>>>
>>>> Cheers,
>>>> Laurent.
>>>>
>>>>>
>>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>>> Commit id:
>>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>>> Benchmark suite: will-it-scale
>>>>> Download link:
>>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>>> Metrics:
>>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>>> THP: enable / disable
>>>>> nr_task: 100%
>>>>>
>>>>> 1. Regressions:
>>>>> a) THP enabled:
>>>>> testcase base change head metric
>>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>>
>>>>> b) THP disabled:
>>>>> testcase base change head metric
>>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>>
>>>>> 2. Improvements:
>>>>> a) THP enabled:
>>>>> testcase base change head metric
>>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>>
>>>>> b) THP disabled:
>>>>> testcase base change head metric
>>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>>
>>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>>> on head commit is better than that on base commit for this benchmark.
>>>>>
>>>>>
>>>>> Best regards
>>>>> Haiyan Song
>>>>>
>>>>> ________________________________________
>>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>>
>>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>>> page fault without holding the mm semaphore [1].
>>>>>
>>>>> The idea is to try to handle user space page faults without holding the
>>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>>> process since the page fault handler will not wait for other threads memory
>>>>> layout change to be done, assuming that this change is done in another part
>>>>> of the process's memory space. This type page fault is named speculative
>>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>>> is failing its processing and a classic page fault is then tried.
>>>>>
>>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>>> freeing operation which was hitting the performance by 20% as reported by
>>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>>> limiting the locking contention to these operations which are expected to
>>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>>> our back a reference count is added and 2 services (get_vma() and
>>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>>> benchmark anymore.
>>>>>
>>>>> The VMA's attributes checked during the speculative page fault processing
>>>>> have to be protected against parallel changes. This is done by using a per
>>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>>> handler to fast check for parallel changes in progress and to abort the
>>>>> speculative page fault in that case.
>>>>>
>>>>> Once the VMA has been found, the speculative page fault handler would check
>>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>>> checked during the page fault are modified.
>>>>>
>>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>>> leading to touching this PTE will need to lock the page table, so no
>>>>> parallel change is possible at this time.
>>>>>
>>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>>> different from the one recorded at the beginning of the SPF operation, the
>>>>> classic page fault handler will be called to handle the operation while
>>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>>> PTE.
>>>>>
>>>>> In pseudo code, this could be seen as:
>>>>> speculative_page_fault()
>>>>> {
>>>>> vma = get_vma()
>>>>> check vma sequence count
>>>>> check vma's support
>>>>> disable interrupt
>>>>> check pgd,p4d,...,pte
>>>>> save pmd and pte in vmf
>>>>> save vma sequence counter in vmf
>>>>> enable interrupt
>>>>> check vma sequence count
>>>>> handle_pte_fault(vma)
>>>>> ..
>>>>> page = alloc_page()
>>>>> pte_map_lock()
>>>>> disable interrupt
>>>>> abort if sequence counter has changed
>>>>> abort if pmd or pte has changed
>>>>> pte map and lock
>>>>> enable interrupt
>>>>> if abort
>>>>> free page
>>>>> abort
>>>>> ...
>>>>> }
>>>>>
>>>>> arch_fault_handler()
>>>>> {
>>>>> if (speculative_page_fault(&vma))
>>>>> goto done
>>>>> again:
>>>>> lock(mmap_sem)
>>>>> vma = find_vma();
>>>>> handle_pte_fault(vma);
>>>>> if retry
>>>>> unlock(mmap_sem)
>>>>> goto again;
>>>>> done:
>>>>> handle fault error
>>>>> }
>>>>>
>>>>> Support for THP is not done because when checking for the PMD, we can be
>>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>>
>>>>> This series add a new software performance event named 'speculative-faults'
>>>>> or 'spf'. It counts the number of successful page fault event handled
>>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>>> counting the total number of page fault events while 'spf' is only counting
>>>>> the part of the faults processed speculatively.
>>>>>
>>>>> There are some trace events introduced by this series. They allow
>>>>> identifying why the page faults were not processed speculatively. This
>>>>> doesn't take in account the faults generated by a monothreaded process
>>>>> which directly processed while holding the mmap_sem. This trace events are
>>>>> grouped in a system named 'pagefault', they are:
>>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>>> back.
>>>>>
>>>>> To record all the related events, the easier is to run perf with the
>>>>> following arguments :
>>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>>
>>>>> There is also a dedicated vmstat counter showing the number of successful
>>>>> page fault handled speculatively. I can be seen this way:
>>>>> $ grep speculative_pgfault /proc/vmstat
>>>>>
>>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>>> on x86, PowerPC and arm64.
>>>>>
>>>>> ---------------------
>>>>> Real Workload results
>>>>>
>>>>> As mentioned in previous email, we did non official runs using a "popular
>>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>>> which showed a 30% improvements in the number of transaction processed per
>>>>> second. This run has been done on the v6 series, but changes introduced in
>>>>> this new version should not impact the performance boost seen.
>>>>>
>>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>>> series:
>>>>> vanilla spf
>>>>> faults 89.418 101.364 +13%
>>>>> spf n/a 97.989
>>>>>
>>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>>> way.
>>>>>
>>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>>> it a try on an android device. He reported that the application launch time
>>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>>> 20%.
>>>>>
>>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>>
>>>>> Application 4.9 4.9+spf delta
>>>>> com.tencent.mm 416 389 -7%
>>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>>> com.tencent.mtt 455 454 0%
>>>>> com.qqgame.hlddz 1497 1409 -6%
>>>>> com.autonavi.minimap 711 701 -1%
>>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>>> com.immomo.momo 501 487 -3%
>>>>> com.tencent.peng 2145 2112 -2%
>>>>> com.smile.gifmaker 491 461 -6%
>>>>> com.baidu.BaiduMap 479 366 -23%
>>>>> com.taobao.taobao 1341 1198 -11%
>>>>> com.baidu.searchbox 333 314 -6%
>>>>> com.tencent.mobileqq 394 384 -3%
>>>>> com.sina.weibo 907 906 0%
>>>>> com.youku.phone 816 731 -11%
>>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>>> com.UCMobile 415 411 -1%
>>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>>> com.tencent.qqmusic 336 329 -2%
>>>>> com.sankuai.meituan 1661 1302 -22%
>>>>> com.netease.cloudmusic 1193 1200 1%
>>>>> air.tv.douyu.android 4257 4152 -2%
>>>>>
>>>>> ------------------
>>>>> Benchmarks results
>>>>>
>>>>> Base kernel is v4.17.0-rc4-mm1
>>>>> SPF is BASE + this series
>>>>>
>>>>> Kernbench:
>>>>> ----------
>>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>>> kernel (kernel is build 5 times):
>>>>>
>>>>> Average Half load -j 8
>>>>> Run (std deviation)
>>>>> BASE SPF
>>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>>
>>>>> Average Optimal load -j 16
>>>>> Run (std deviation)
>>>>> BASE SPF
>>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>>
>>>>>
>>>>> During a run on the SPF, perf events were captured:
>>>>> Performance counter stats for '../kernbench -M':
>>>>> 526743764 faults
>>>>> 210 spf
>>>>> 3 pagefault:spf_vma_changed
>>>>> 0 pagefault:spf_vma_noanon
>>>>> 2278 pagefault:spf_vma_notsup
>>>>> 0 pagefault:spf_vma_access
>>>>> 0 pagefault:spf_pmd_changed
>>>>>
>>>>> Very few speculative page faults were recorded as most of the processes
>>>>> involved are monothreaded (sounds that on this architecture some threads
>>>>> were created during the kernel build processing).
>>>>>
>>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>>
>>>>> Average Half load -j 40
>>>>> Run (std deviation)
>>>>> BASE SPF
>>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>>
>>>>> Average Optimal load -j 80
>>>>> Run (std deviation)
>>>>> BASE SPF
>>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>>
>>>>> During a run on the SPF, perf events were captured:
>>>>> Performance counter stats for '../kernbench -M':
>>>>> 116730856 faults
>>>>> 0 spf
>>>>> 3 pagefault:spf_vma_changed
>>>>> 0 pagefault:spf_vma_noanon
>>>>> 476 pagefault:spf_vma_notsup
>>>>> 0 pagefault:spf_vma_access
>>>>> 0 pagefault:spf_pmd_changed
>>>>>
>>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>>> there is no impact on the performance.
>>>>>
>>>>> Ebizzy:
>>>>> -------
>>>>> The test is counting the number of records per second it can manage, the
>>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>>> consistent result I repeated the test 100 times and measure the average
>>>>> result. The number is the record processes per second, the higher is the
>>>>> best.
>>>>>
>>>>> BASE SPF delta
>>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>>
>>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>>> Performance counter stats for './ebizzy -mTt 16':
>>>>> 1706379 faults
>>>>> 1674599 spf
>>>>> 30588 pagefault:spf_vma_changed
>>>>> 0 pagefault:spf_vma_noanon
>>>>> 363 pagefault:spf_vma_notsup
>>>>> 0 pagefault:spf_vma_access
>>>>> 0 pagefault:spf_pmd_changed
>>>>>
>>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>>> Performance counter stats for './ebizzy -mTt 80':
>>>>> 1874773 faults
>>>>> 1461153 spf
>>>>> 413293 pagefault:spf_vma_changed
>>>>> 0 pagefault:spf_vma_noanon
>>>>> 200 pagefault:spf_vma_notsup
>>>>> 0 pagefault:spf_vma_access
>>>>> 0 pagefault:spf_pmd_changed
>>>>>
>>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>>> leading the ebizzy performance boost.
>>>>>
>>>>> ------------------
>>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>>> and Minchan Kim, hopefully.
>>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>>> __do_page_fault().
>>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>>> instead
>>>>> of aborting the speculative page fault handling. Dropping the now
>>>>> useless
>>>>> trace event pagefault:spf_pte_lock.
>>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>>> handling when retrying is needed. This adds a lot of complexity and
>>>>> additional tests done didn't show a significant performance improvement.
>>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>>
>>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>>
>>>>>
>>>>> Laurent Dufour (20):
>>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>>> mm: make pte_unmap_same compatible with SPF
>>>>> mm: introduce INIT_VMA()
>>>>> mm: protect VMA modifications using VMA sequence count
>>>>> mm: protect mremap() against SPF hanlder
>>>>> mm: protect SPF handler against anon_vma changes
>>>>> mm: cache some VMA fields in the vm_fault structure
>>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>>> mm: introduce __vm_normal_page()
>>>>> mm: introduce __page_add_new_anon_rmap()
>>>>> mm: protect mm_rb tree with a rwlock
>>>>> mm: adding speculative page fault failure trace events
>>>>> perf: add a speculative page fault sw event
>>>>> perf tools: add support for the SPF perf event
>>>>> mm: add speculative page fault vmstats
>>>>> powerpc/mm: add speculative page fault
>>>>>
>>>>> Mahendran Ganesh (2):
>>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>>> arm64/mm: add speculative page fault
>>>>>
>>>>> Peter Zijlstra (4):
>>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>>> mm: VMA sequence count
>>>>> mm: provide speculative fault infrastructure
>>>>> x86/mm: add speculative pagefault handling
>>>>>
>>>>> arch/arm64/Kconfig | 1 +
>>>>> arch/arm64/mm/fault.c | 12 +
>>>>> arch/powerpc/Kconfig | 1 +
>>>>> arch/powerpc/mm/fault.c | 16 +
>>>>> arch/x86/Kconfig | 1 +
>>>>> arch/x86/mm/fault.c | 27 +-
>>>>> fs/exec.c | 2 +-
>>>>> fs/proc/task_mmu.c | 5 +-
>>>>> fs/userfaultfd.c | 17 +-
>>>>> include/linux/hugetlb_inline.h | 2 +-
>>>>> include/linux/migrate.h | 4 +-
>>>>> include/linux/mm.h | 136 +++++++-
>>>>> include/linux/mm_types.h | 7 +
>>>>> include/linux/pagemap.h | 4 +-
>>>>> include/linux/rmap.h | 12 +-
>>>>> include/linux/swap.h | 10 +-
>>>>> include/linux/vm_event_item.h | 3 +
>>>>> include/trace/events/pagefault.h | 80 +++++
>>>>> include/uapi/linux/perf_event.h | 1 +
>>>>> kernel/fork.c | 5 +-
>>>>> mm/Kconfig | 22 ++
>>>>> mm/huge_memory.c | 6 +-
>>>>> mm/hugetlb.c | 2 +
>>>>> mm/init-mm.c | 3 +
>>>>> mm/internal.h | 20 ++
>>>>> mm/khugepaged.c | 5 +
>>>>> mm/madvise.c | 6 +-
>>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>>> mm/mempolicy.c | 51 ++-
>>>>> mm/migrate.c | 6 +-
>>>>> mm/mlock.c | 13 +-
>>>>> mm/mmap.c | 229 ++++++++++---
>>>>> mm/mprotect.c | 4 +-
>>>>> mm/mremap.c | 13 +
>>>>> mm/nommu.c | 2 +-
>>>>> mm/rmap.c | 5 +-
>>>>> mm/swap.c | 6 +-
>>>>> mm/swap_state.c | 8 +-
>>>>> mm/vmstat.c | 5 +-
>>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>>> tools/perf/util/evsel.c | 1 +
>>>>> tools/perf/util/parse-events.c | 4 +
>>>>> tools/perf/util/parse-events.l | 1 +
>>>>> tools/perf/util/python.c | 1 +
>>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>>> create mode 100644 include/trace/events/pagefault.h
>>>>>
>>>>> --
>>>>> 2.7.4
>>>>>
>>>>>
>>>>
>>>
>>
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-07-02 8:59 ` Laurent Dufour
@ 2018-07-04 3:23 ` Song, HaiyanX
2018-07-04 7:51 ` Laurent Dufour
0 siblings, 1 reply; 46+ messages in thread
From: Song, HaiyanX @ 2018-07-04 3:23 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
Hi Laurent,
For the test result on Intel 4s skylake platform (192 CPUs, 768G Memory), the below test cases all were run 3 times.
I check the test results, only page_fault3_thread/enable THP have 6% stddev for head commit, other tests have lower stddev.
And I did not find other high variation on test case result.
a). Enable THP
testcase base stddev change head stddev metric
page_fault3/enable THP 10519 ± 3% -20.5% 8368 ±6% will-it-scale.per_thread_ops
page_fault2/enalbe THP 8281 ± 2% -18.8% 6728 will-it-scale.per_thread_ops
brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
b). Disable THP
page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
Best regards,
Haiyan Song
________________________________________
From: Laurent Dufour [ldufour@linux.vnet.ibm.com]
Sent: Monday, July 02, 2018 4:59 PM
To: Song, HaiyanX
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: Re: [PATCH v11 00/26] Speculative page faults
On 11/06/2018 09:49, Song, HaiyanX wrote:
> Hi Laurent,
>
> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
> V9 patch serials.
>
> The regression result is sorted by the metric will-it-scale.per_thread_ops.
> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
> commit id:
> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
> Benchmark: will-it-scale
> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>
> Metrics:
> will-it-scale.per_process_ops=processes/nr_cpu
> will-it-scale.per_thread_ops=threads/nr_cpu
> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
> THP: enable / disable
> nr_task:100%
>
> 1. Regressions:
>
> a). Enable THP
> testcase base change head metric
> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>
> b). Disable THP
> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>
> Notes: for the above values of test result, the higher is better.
I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
get reproducible results. The results have huge variation, even on the vanilla
kernel, and I can't state on any changes due to that.
I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
measure any changes between the vanilla and the SPF patched ones:
test THP enabled 4.17.0-rc4-mm1 spf delta
page_fault3_threads 2697.7 2683.5 -0.53%
page_fault2_threads 170660.6 169574.1 -0.64%
context_switch1_threads 6915269.2 6877507.3 -0.55%
context_switch1_processes 6478076.2 6529493.5 0.79%
brk1 243391.2 238527.5 -2.00%
Tests were run 10 times, no high variation detected.
Did you see high variation on your side ? How many times the test were run to
compute the average values ?
Thanks,
Laurent.
>
> 2. Improvement: not found improvement based on the selected test cases.
>
>
> Best regards
> Haiyan Song
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Monday, May 28, 2018 4:54 PM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> On 28/05/2018 10:22, Haiyan Song wrote:
>> Hi Laurent,
>>
>> Yes, these tests are done on V9 patch.
>
> Do you plan to give this V11 a run ?
>
>>
>>
>> Best regards,
>> Haiyan Song
>>
>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>
>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>> tested on Intel 4s Skylake platform.
>>>
>>> Hi,
>>>
>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>> series" while responding to the v11 header series...
>>> Were these tests done on v9 or v11 ?
>>>
>>> Cheers,
>>> Laurent.
>>>
>>>>
>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>> Commit id:
>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>> Benchmark suite: will-it-scale
>>>> Download link:
>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>> Metrics:
>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>> THP: enable / disable
>>>> nr_task: 100%
>>>>
>>>> 1. Regressions:
>>>> a) THP enabled:
>>>> testcase base change head metric
>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>
>>>> b) THP disabled:
>>>> testcase base change head metric
>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>
>>>> 2. Improvements:
>>>> a) THP enabled:
>>>> testcase base change head metric
>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>
>>>> b) THP disabled:
>>>> testcase base change head metric
>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>
>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>> on head commit is better than that on base commit for this benchmark.
>>>>
>>>>
>>>> Best regards
>>>> Haiyan Song
>>>>
>>>> ________________________________________
>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>> page fault without holding the mm semaphore [1].
>>>>
>>>> The idea is to try to handle user space page faults without holding the
>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>> process since the page fault handler will not wait for other threads memory
>>>> layout change to be done, assuming that this change is done in another part
>>>> of the process's memory space. This type page fault is named speculative
>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>> is failing its processing and a classic page fault is then tried.
>>>>
>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>> freeing operation which was hitting the performance by 20% as reported by
>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>> limiting the locking contention to these operations which are expected to
>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>> our back a reference count is added and 2 services (get_vma() and
>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>> benchmark anymore.
>>>>
>>>> The VMA's attributes checked during the speculative page fault processing
>>>> have to be protected against parallel changes. This is done by using a per
>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>> handler to fast check for parallel changes in progress and to abort the
>>>> speculative page fault in that case.
>>>>
>>>> Once the VMA has been found, the speculative page fault handler would check
>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>> checked during the page fault are modified.
>>>>
>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>> leading to touching this PTE will need to lock the page table, so no
>>>> parallel change is possible at this time.
>>>>
>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>> different from the one recorded at the beginning of the SPF operation, the
>>>> classic page fault handler will be called to handle the operation while
>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>> PTE.
>>>>
>>>> In pseudo code, this could be seen as:
>>>> speculative_page_fault()
>>>> {
>>>> vma = get_vma()
>>>> check vma sequence count
>>>> check vma's support
>>>> disable interrupt
>>>> check pgd,p4d,...,pte
>>>> save pmd and pte in vmf
>>>> save vma sequence counter in vmf
>>>> enable interrupt
>>>> check vma sequence count
>>>> handle_pte_fault(vma)
>>>> ..
>>>> page = alloc_page()
>>>> pte_map_lock()
>>>> disable interrupt
>>>> abort if sequence counter has changed
>>>> abort if pmd or pte has changed
>>>> pte map and lock
>>>> enable interrupt
>>>> if abort
>>>> free page
>>>> abort
>>>> ...
>>>> }
>>>>
>>>> arch_fault_handler()
>>>> {
>>>> if (speculative_page_fault(&vma))
>>>> goto done
>>>> again:
>>>> lock(mmap_sem)
>>>> vma = find_vma();
>>>> handle_pte_fault(vma);
>>>> if retry
>>>> unlock(mmap_sem)
>>>> goto again;
>>>> done:
>>>> handle fault error
>>>> }
>>>>
>>>> Support for THP is not done because when checking for the PMD, we can be
>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>
>>>> This series add a new software performance event named 'speculative-faults'
>>>> or 'spf'. It counts the number of successful page fault event handled
>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>> counting the total number of page fault events while 'spf' is only counting
>>>> the part of the faults processed speculatively.
>>>>
>>>> There are some trace events introduced by this series. They allow
>>>> identifying why the page faults were not processed speculatively. This
>>>> doesn't take in account the faults generated by a monothreaded process
>>>> which directly processed while holding the mmap_sem. This trace events are
>>>> grouped in a system named 'pagefault', they are:
>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>> back.
>>>>
>>>> To record all the related events, the easier is to run perf with the
>>>> following arguments :
>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>
>>>> There is also a dedicated vmstat counter showing the number of successful
>>>> page fault handled speculatively. I can be seen this way:
>>>> $ grep speculative_pgfault /proc/vmstat
>>>>
>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>> on x86, PowerPC and arm64.
>>>>
>>>> ---------------------
>>>> Real Workload results
>>>>
>>>> As mentioned in previous email, we did non official runs using a "popular
>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>> which showed a 30% improvements in the number of transaction processed per
>>>> second. This run has been done on the v6 series, but changes introduced in
>>>> this new version should not impact the performance boost seen.
>>>>
>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>> series:
>>>> vanilla spf
>>>> faults 89.418 101.364 +13%
>>>> spf n/a 97.989
>>>>
>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>> way.
>>>>
>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>> it a try on an android device. He reported that the application launch time
>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>> 20%.
>>>>
>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>
>>>> Application 4.9 4.9+spf delta
>>>> com.tencent.mm 416 389 -7%
>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>> com.tencent.mtt 455 454 0%
>>>> com.qqgame.hlddz 1497 1409 -6%
>>>> com.autonavi.minimap 711 701 -1%
>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>> com.immomo.momo 501 487 -3%
>>>> com.tencent.peng 2145 2112 -2%
>>>> com.smile.gifmaker 491 461 -6%
>>>> com.baidu.BaiduMap 479 366 -23%
>>>> com.taobao.taobao 1341 1198 -11%
>>>> com.baidu.searchbox 333 314 -6%
>>>> com.tencent.mobileqq 394 384 -3%
>>>> com.sina.weibo 907 906 0%
>>>> com.youku.phone 816 731 -11%
>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>> com.UCMobile 415 411 -1%
>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>> com.tencent.qqmusic 336 329 -2%
>>>> com.sankuai.meituan 1661 1302 -22%
>>>> com.netease.cloudmusic 1193 1200 1%
>>>> air.tv.douyu.android 4257 4152 -2%
>>>>
>>>> ------------------
>>>> Benchmarks results
>>>>
>>>> Base kernel is v4.17.0-rc4-mm1
>>>> SPF is BASE + this series
>>>>
>>>> Kernbench:
>>>> ----------
>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>> kernel (kernel is build 5 times):
>>>>
>>>> Average Half load -j 8
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>
>>>> Average Optimal load -j 16
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>
>>>>
>>>> During a run on the SPF, perf events were captured:
>>>> Performance counter stats for '../kernbench -M':
>>>> 526743764 faults
>>>> 210 spf
>>>> 3 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 2278 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> Very few speculative page faults were recorded as most of the processes
>>>> involved are monothreaded (sounds that on this architecture some threads
>>>> were created during the kernel build processing).
>>>>
>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>
>>>> Average Half load -j 40
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>
>>>> Average Optimal load -j 80
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>
>>>> During a run on the SPF, perf events were captured:
>>>> Performance counter stats for '../kernbench -M':
>>>> 116730856 faults
>>>> 0 spf
>>>> 3 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 476 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>> there is no impact on the performance.
>>>>
>>>> Ebizzy:
>>>> -------
>>>> The test is counting the number of records per second it can manage, the
>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>> consistent result I repeated the test 100 times and measure the average
>>>> result. The number is the record processes per second, the higher is the
>>>> best.
>>>>
>>>> BASE SPF delta
>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>
>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>> Performance counter stats for './ebizzy -mTt 16':
>>>> 1706379 faults
>>>> 1674599 spf
>>>> 30588 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 363 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>> Performance counter stats for './ebizzy -mTt 80':
>>>> 1874773 faults
>>>> 1461153 spf
>>>> 413293 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 200 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>> leading the ebizzy performance boost.
>>>>
>>>> ------------------
>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>> and Minchan Kim, hopefully.
>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>> __do_page_fault().
>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>> instead
>>>> of aborting the speculative page fault handling. Dropping the now
>>>> useless
>>>> trace event pagefault:spf_pte_lock.
>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>> handling when retrying is needed. This adds a lot of complexity and
>>>> additional tests done didn't show a significant performance improvement.
>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>
>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>
>>>>
>>>> Laurent Dufour (20):
>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>> mm: make pte_unmap_same compatible with SPF
>>>> mm: introduce INIT_VMA()
>>>> mm: protect VMA modifications using VMA sequence count
>>>> mm: protect mremap() against SPF hanlder
>>>> mm: protect SPF handler against anon_vma changes
>>>> mm: cache some VMA fields in the vm_fault structure
>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>> mm: introduce __vm_normal_page()
>>>> mm: introduce __page_add_new_anon_rmap()
>>>> mm: protect mm_rb tree with a rwlock
>>>> mm: adding speculative page fault failure trace events
>>>> perf: add a speculative page fault sw event
>>>> perf tools: add support for the SPF perf event
>>>> mm: add speculative page fault vmstats
>>>> powerpc/mm: add speculative page fault
>>>>
>>>> Mahendran Ganesh (2):
>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> arm64/mm: add speculative page fault
>>>>
>>>> Peter Zijlstra (4):
>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>> mm: VMA sequence count
>>>> mm: provide speculative fault infrastructure
>>>> x86/mm: add speculative pagefault handling
>>>>
>>>> arch/arm64/Kconfig | 1 +
>>>> arch/arm64/mm/fault.c | 12 +
>>>> arch/powerpc/Kconfig | 1 +
>>>> arch/powerpc/mm/fault.c | 16 +
>>>> arch/x86/Kconfig | 1 +
>>>> arch/x86/mm/fault.c | 27 +-
>>>> fs/exec.c | 2 +-
>>>> fs/proc/task_mmu.c | 5 +-
>>>> fs/userfaultfd.c | 17 +-
>>>> include/linux/hugetlb_inline.h | 2 +-
>>>> include/linux/migrate.h | 4 +-
>>>> include/linux/mm.h | 136 +++++++-
>>>> include/linux/mm_types.h | 7 +
>>>> include/linux/pagemap.h | 4 +-
>>>> include/linux/rmap.h | 12 +-
>>>> include/linux/swap.h | 10 +-
>>>> include/linux/vm_event_item.h | 3 +
>>>> include/trace/events/pagefault.h | 80 +++++
>>>> include/uapi/linux/perf_event.h | 1 +
>>>> kernel/fork.c | 5 +-
>>>> mm/Kconfig | 22 ++
>>>> mm/huge_memory.c | 6 +-
>>>> mm/hugetlb.c | 2 +
>>>> mm/init-mm.c | 3 +
>>>> mm/internal.h | 20 ++
>>>> mm/khugepaged.c | 5 +
>>>> mm/madvise.c | 6 +-
>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>> mm/mempolicy.c | 51 ++-
>>>> mm/migrate.c | 6 +-
>>>> mm/mlock.c | 13 +-
>>>> mm/mmap.c | 229 ++++++++++---
>>>> mm/mprotect.c | 4 +-
>>>> mm/mremap.c | 13 +
>>>> mm/nommu.c | 2 +-
>>>> mm/rmap.c | 5 +-
>>>> mm/swap.c | 6 +-
>>>> mm/swap_state.c | 8 +-
>>>> mm/vmstat.c | 5 +-
>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>> tools/perf/util/evsel.c | 1 +
>>>> tools/perf/util/parse-events.c | 4 +
>>>> tools/perf/util/parse-events.l | 1 +
>>>> tools/perf/util/python.c | 1 +
>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>> create mode 100644 include/trace/events/pagefault.h
>>>>
>>>> --
>>>> 2.7.4
>>>>
>>>>
>>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-06-11 7:49 ` Song, HaiyanX
2018-06-11 15:15 ` Laurent Dufour
@ 2018-07-02 8:59 ` Laurent Dufour
2018-07-04 3:23 ` Song, HaiyanX
1 sibling, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2018-07-02 8:59 UTC (permalink / raw)
To: Song, HaiyanX
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
On 11/06/2018 09:49, Song, HaiyanX wrote:
> Hi Laurent,
>
> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
> V9 patch serials.
>
> The regression result is sorted by the metric will-it-scale.per_thread_ops.
> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
> commit id:
> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
> Benchmark: will-it-scale
> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>
> Metrics:
> will-it-scale.per_process_ops=processes/nr_cpu
> will-it-scale.per_thread_ops=threads/nr_cpu
> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
> THP: enable / disable
> nr_task:100%
>
> 1. Regressions:
>
> a). Enable THP
> testcase base change head metric
> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>
> b). Disable THP
> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>
> Notes: for the above values of test result, the higher is better.
I tried the same tests on my PowerPC victim VM (1024 CPUs, 11TB) and I can't
get reproducible results. The results have huge variation, even on the vanilla
kernel, and I can't state on any changes due to that.
I tried on smaller node (80 CPUs, 32G), and the tests ran better, but I didn't
measure any changes between the vanilla and the SPF patched ones:
test THP enabled 4.17.0-rc4-mm1 spf delta
page_fault3_threads 2697.7 2683.5 -0.53%
page_fault2_threads 170660.6 169574.1 -0.64%
context_switch1_threads 6915269.2 6877507.3 -0.55%
context_switch1_processes 6478076.2 6529493.5 0.79%
brk1 243391.2 238527.5 -2.00%
Tests were run 10 times, no high variation detected.
Did you see high variation on your side ? How many times the test were run to
compute the average values ?
Thanks,
Laurent.
>
> 2. Improvement: not found improvement based on the selected test cases.
>
>
> Best regards
> Haiyan Song
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Monday, May 28, 2018 4:54 PM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> On 28/05/2018 10:22, Haiyan Song wrote:
>> Hi Laurent,
>>
>> Yes, these tests are done on V9 patch.
>
> Do you plan to give this V11 a run ?
>
>>
>>
>> Best regards,
>> Haiyan Song
>>
>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>
>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>> tested on Intel 4s Skylake platform.
>>>
>>> Hi,
>>>
>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>> series" while responding to the v11 header series...
>>> Were these tests done on v9 or v11 ?
>>>
>>> Cheers,
>>> Laurent.
>>>
>>>>
>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>> Commit id:
>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>> Benchmark suite: will-it-scale
>>>> Download link:
>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>> Metrics:
>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>> THP: enable / disable
>>>> nr_task: 100%
>>>>
>>>> 1. Regressions:
>>>> a) THP enabled:
>>>> testcase base change head metric
>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>
>>>> b) THP disabled:
>>>> testcase base change head metric
>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>
>>>> 2. Improvements:
>>>> a) THP enabled:
>>>> testcase base change head metric
>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>
>>>> b) THP disabled:
>>>> testcase base change head metric
>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>
>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>> on head commit is better than that on base commit for this benchmark.
>>>>
>>>>
>>>> Best regards
>>>> Haiyan Song
>>>>
>>>> ________________________________________
>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>> page fault without holding the mm semaphore [1].
>>>>
>>>> The idea is to try to handle user space page faults without holding the
>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>> process since the page fault handler will not wait for other threads memory
>>>> layout change to be done, assuming that this change is done in another part
>>>> of the process's memory space. This type page fault is named speculative
>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>> is failing its processing and a classic page fault is then tried.
>>>>
>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>> freeing operation which was hitting the performance by 20% as reported by
>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>> limiting the locking contention to these operations which are expected to
>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>> our back a reference count is added and 2 services (get_vma() and
>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>> benchmark anymore.
>>>>
>>>> The VMA's attributes checked during the speculative page fault processing
>>>> have to be protected against parallel changes. This is done by using a per
>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>> handler to fast check for parallel changes in progress and to abort the
>>>> speculative page fault in that case.
>>>>
>>>> Once the VMA has been found, the speculative page fault handler would check
>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>> checked during the page fault are modified.
>>>>
>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>> leading to touching this PTE will need to lock the page table, so no
>>>> parallel change is possible at this time.
>>>>
>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>> different from the one recorded at the beginning of the SPF operation, the
>>>> classic page fault handler will be called to handle the operation while
>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>> PTE.
>>>>
>>>> In pseudo code, this could be seen as:
>>>> speculative_page_fault()
>>>> {
>>>> vma = get_vma()
>>>> check vma sequence count
>>>> check vma's support
>>>> disable interrupt
>>>> check pgd,p4d,...,pte
>>>> save pmd and pte in vmf
>>>> save vma sequence counter in vmf
>>>> enable interrupt
>>>> check vma sequence count
>>>> handle_pte_fault(vma)
>>>> ..
>>>> page = alloc_page()
>>>> pte_map_lock()
>>>> disable interrupt
>>>> abort if sequence counter has changed
>>>> abort if pmd or pte has changed
>>>> pte map and lock
>>>> enable interrupt
>>>> if abort
>>>> free page
>>>> abort
>>>> ...
>>>> }
>>>>
>>>> arch_fault_handler()
>>>> {
>>>> if (speculative_page_fault(&vma))
>>>> goto done
>>>> again:
>>>> lock(mmap_sem)
>>>> vma = find_vma();
>>>> handle_pte_fault(vma);
>>>> if retry
>>>> unlock(mmap_sem)
>>>> goto again;
>>>> done:
>>>> handle fault error
>>>> }
>>>>
>>>> Support for THP is not done because when checking for the PMD, we can be
>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>
>>>> This series add a new software performance event named 'speculative-faults'
>>>> or 'spf'. It counts the number of successful page fault event handled
>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>> counting the total number of page fault events while 'spf' is only counting
>>>> the part of the faults processed speculatively.
>>>>
>>>> There are some trace events introduced by this series. They allow
>>>> identifying why the page faults were not processed speculatively. This
>>>> doesn't take in account the faults generated by a monothreaded process
>>>> which directly processed while holding the mmap_sem. This trace events are
>>>> grouped in a system named 'pagefault', they are:
>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>> back.
>>>>
>>>> To record all the related events, the easier is to run perf with the
>>>> following arguments :
>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>
>>>> There is also a dedicated vmstat counter showing the number of successful
>>>> page fault handled speculatively. I can be seen this way:
>>>> $ grep speculative_pgfault /proc/vmstat
>>>>
>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>> on x86, PowerPC and arm64.
>>>>
>>>> ---------------------
>>>> Real Workload results
>>>>
>>>> As mentioned in previous email, we did non official runs using a "popular
>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>> which showed a 30% improvements in the number of transaction processed per
>>>> second. This run has been done on the v6 series, but changes introduced in
>>>> this new version should not impact the performance boost seen.
>>>>
>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>> series:
>>>> vanilla spf
>>>> faults 89.418 101.364 +13%
>>>> spf n/a 97.989
>>>>
>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>> way.
>>>>
>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>> it a try on an android device. He reported that the application launch time
>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>> 20%.
>>>>
>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>
>>>> Application 4.9 4.9+spf delta
>>>> com.tencent.mm 416 389 -7%
>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>> com.tencent.mtt 455 454 0%
>>>> com.qqgame.hlddz 1497 1409 -6%
>>>> com.autonavi.minimap 711 701 -1%
>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>> com.immomo.momo 501 487 -3%
>>>> com.tencent.peng 2145 2112 -2%
>>>> com.smile.gifmaker 491 461 -6%
>>>> com.baidu.BaiduMap 479 366 -23%
>>>> com.taobao.taobao 1341 1198 -11%
>>>> com.baidu.searchbox 333 314 -6%
>>>> com.tencent.mobileqq 394 384 -3%
>>>> com.sina.weibo 907 906 0%
>>>> com.youku.phone 816 731 -11%
>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>> com.UCMobile 415 411 -1%
>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>> com.tencent.qqmusic 336 329 -2%
>>>> com.sankuai.meituan 1661 1302 -22%
>>>> com.netease.cloudmusic 1193 1200 1%
>>>> air.tv.douyu.android 4257 4152 -2%
>>>>
>>>> ------------------
>>>> Benchmarks results
>>>>
>>>> Base kernel is v4.17.0-rc4-mm1
>>>> SPF is BASE + this series
>>>>
>>>> Kernbench:
>>>> ----------
>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>> kernel (kernel is build 5 times):
>>>>
>>>> Average Half load -j 8
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>
>>>> Average Optimal load -j 16
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>
>>>>
>>>> During a run on the SPF, perf events were captured:
>>>> Performance counter stats for '../kernbench -M':
>>>> 526743764 faults
>>>> 210 spf
>>>> 3 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 2278 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> Very few speculative page faults were recorded as most of the processes
>>>> involved are monothreaded (sounds that on this architecture some threads
>>>> were created during the kernel build processing).
>>>>
>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>
>>>> Average Half load -j 40
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>
>>>> Average Optimal load -j 80
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>
>>>> During a run on the SPF, perf events were captured:
>>>> Performance counter stats for '../kernbench -M':
>>>> 116730856 faults
>>>> 0 spf
>>>> 3 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 476 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>> there is no impact on the performance.
>>>>
>>>> Ebizzy:
>>>> -------
>>>> The test is counting the number of records per second it can manage, the
>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>> consistent result I repeated the test 100 times and measure the average
>>>> result. The number is the record processes per second, the higher is the
>>>> best.
>>>>
>>>> BASE SPF delta
>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>
>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>> Performance counter stats for './ebizzy -mTt 16':
>>>> 1706379 faults
>>>> 1674599 spf
>>>> 30588 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 363 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>> Performance counter stats for './ebizzy -mTt 80':
>>>> 1874773 faults
>>>> 1461153 spf
>>>> 413293 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 200 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>> leading the ebizzy performance boost.
>>>>
>>>> ------------------
>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>> and Minchan Kim, hopefully.
>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>> __do_page_fault().
>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>> instead
>>>> of aborting the speculative page fault handling. Dropping the now
>>>> useless
>>>> trace event pagefault:spf_pte_lock.
>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>> handling when retrying is needed. This adds a lot of complexity and
>>>> additional tests done didn't show a significant performance improvement.
>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>
>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>
>>>>
>>>> Laurent Dufour (20):
>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>> mm: make pte_unmap_same compatible with SPF
>>>> mm: introduce INIT_VMA()
>>>> mm: protect VMA modifications using VMA sequence count
>>>> mm: protect mremap() against SPF hanlder
>>>> mm: protect SPF handler against anon_vma changes
>>>> mm: cache some VMA fields in the vm_fault structure
>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>> mm: introduce __vm_normal_page()
>>>> mm: introduce __page_add_new_anon_rmap()
>>>> mm: protect mm_rb tree with a rwlock
>>>> mm: adding speculative page fault failure trace events
>>>> perf: add a speculative page fault sw event
>>>> perf tools: add support for the SPF perf event
>>>> mm: add speculative page fault vmstats
>>>> powerpc/mm: add speculative page fault
>>>>
>>>> Mahendran Ganesh (2):
>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> arm64/mm: add speculative page fault
>>>>
>>>> Peter Zijlstra (4):
>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>> mm: VMA sequence count
>>>> mm: provide speculative fault infrastructure
>>>> x86/mm: add speculative pagefault handling
>>>>
>>>> arch/arm64/Kconfig | 1 +
>>>> arch/arm64/mm/fault.c | 12 +
>>>> arch/powerpc/Kconfig | 1 +
>>>> arch/powerpc/mm/fault.c | 16 +
>>>> arch/x86/Kconfig | 1 +
>>>> arch/x86/mm/fault.c | 27 +-
>>>> fs/exec.c | 2 +-
>>>> fs/proc/task_mmu.c | 5 +-
>>>> fs/userfaultfd.c | 17 +-
>>>> include/linux/hugetlb_inline.h | 2 +-
>>>> include/linux/migrate.h | 4 +-
>>>> include/linux/mm.h | 136 +++++++-
>>>> include/linux/mm_types.h | 7 +
>>>> include/linux/pagemap.h | 4 +-
>>>> include/linux/rmap.h | 12 +-
>>>> include/linux/swap.h | 10 +-
>>>> include/linux/vm_event_item.h | 3 +
>>>> include/trace/events/pagefault.h | 80 +++++
>>>> include/uapi/linux/perf_event.h | 1 +
>>>> kernel/fork.c | 5 +-
>>>> mm/Kconfig | 22 ++
>>>> mm/huge_memory.c | 6 +-
>>>> mm/hugetlb.c | 2 +
>>>> mm/init-mm.c | 3 +
>>>> mm/internal.h | 20 ++
>>>> mm/khugepaged.c | 5 +
>>>> mm/madvise.c | 6 +-
>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>> mm/mempolicy.c | 51 ++-
>>>> mm/migrate.c | 6 +-
>>>> mm/mlock.c | 13 +-
>>>> mm/mmap.c | 229 ++++++++++---
>>>> mm/mprotect.c | 4 +-
>>>> mm/mremap.c | 13 +
>>>> mm/nommu.c | 2 +-
>>>> mm/rmap.c | 5 +-
>>>> mm/swap.c | 6 +-
>>>> mm/swap_state.c | 8 +-
>>>> mm/vmstat.c | 5 +-
>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>> tools/perf/util/evsel.c | 1 +
>>>> tools/perf/util/parse-events.c | 4 +
>>>> tools/perf/util/parse-events.l | 1 +
>>>> tools/perf/util/python.c | 1 +
>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>> create mode 100644 include/trace/events/pagefault.h
>>>>
>>>> --
>>>> 2.7.4
>>>>
>>>>
>>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-06-11 15:15 ` Laurent Dufour
@ 2018-06-19 9:16 ` Haiyan Song
0 siblings, 0 replies; 46+ messages in thread
From: Haiyan Song @ 2018-06-19 9:16 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
[-- Attachment #1: Type: text/plain, Size: 31691 bytes --]
On Mon, Jun 11, 2018 at 05:15:22PM +0200, Laurent Dufour wrote:
Hi Laurent,
For perf date tested on Intel 4s Skylake platform, here attached the compare result
between base and head commit in attachment, which include the perf-profile comparision information.
And also attached some perf-profile.json captured from test result for page_fault2 and page_fault3 for
checking the regression, thanks.
Best regards,
Haiyan Song
> Hi Haiyan,
>
> I don't have access to the same hardware you ran the test on, but I give a try
> to those test on a Power8 system (2 sockets, 5 cores/s, 8 threads/c, 80 CPUs 32G).
> I run each will-it-scale test 10 times and compute the average.
>
> test THP enabled 4.17.0-rc4-mm1 spf delta
> page_fault3_threads 2697.7 2683.5 -0.53%
> page_fault2_threads 170660.6 169574.1 -0.64%
> context_switch1_threads 6915269.2 6877507.3 -0.55%
> context_switch1_processes 6478076.2 6529493.5 0.79%
> rk1 243391.2 238527.5 -2.00%
>
> Test were launched with the arguments '-t 80 -s 5', only the average report is
> taken in account. Note that page size is 64K by default on ppc64.
>
> It would be nice if you could capture some perf data to figure out why the
> page_fault2/3 are showing such a performance regression.
>
> Thanks,
> Laurent.
>
> On 11/06/2018 09:49, Song, HaiyanX wrote:
> > Hi Laurent,
> >
> > Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
> > tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
> > V9 patch serials.
> >
> > The regression result is sorted by the metric will-it-scale.per_thread_ops.
> > branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
> > commit id:
> > head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
> > base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
> > Benchmark: will-it-scale
> > Download link: https://github.com/antonblanchard/will-it-scale/tree/master
> >
> > Metrics:
> > will-it-scale.per_process_ops=processes/nr_cpu
> > will-it-scale.per_thread_ops=threads/nr_cpu
> > test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
> > THP: enable / disable
> > nr_task:100%
> >
> > 1. Regressions:
> >
> > a). Enable THP
> > testcase base change head metric
> > page_fault3/enable THP 10519 -20.5% 8368 will-it-scale.per_thread_ops
> > page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
> > brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
> > context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
> > context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
> >
> > b). Disable THP
> > page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
> > page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
> > brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
> > context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
> > brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
> > page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
> > context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
> >
> > Notes: for the above values of test result, the higher is better.
> >
> > 2. Improvement: not found improvement based on the selected test cases.
> >
> >
> > Best regards
> > Haiyan Song
> > ________________________________________
> > From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> > Sent: Monday, May 28, 2018 4:54 PM
> > To: Song, HaiyanX
> > Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> > Subject: Re: [PATCH v11 00/26] Speculative page faults
> >
> > On 28/05/2018 10:22, Haiyan Song wrote:
> >> Hi Laurent,
> >>
> >> Yes, these tests are done on V9 patch.
> >
> > Do you plan to give this V11 a run ?
> >
> >>
> >>
> >> Best regards,
> >> Haiyan Song
> >>
> >> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
> >>> On 28/05/2018 07:23, Song, HaiyanX wrote:
> >>>>
> >>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
> >>>> tested on Intel 4s Skylake platform.
> >>>
> >>> Hi,
> >>>
> >>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
> >>> series" while responding to the v11 header series...
> >>> Were these tests done on v9 or v11 ?
> >>>
> >>> Cheers,
> >>> Laurent.
> >>>
> >>>>
> >>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
> >>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
> >>>> Commit id:
> >>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
> >>>> head commit: 0355322b3577eeab7669066df42c550a56801110
> >>>> Benchmark suite: will-it-scale
> >>>> Download link:
> >>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
> >>>> Metrics:
> >>>> will-it-scale.per_process_ops=processes/nr_cpu
> >>>> will-it-scale.per_thread_ops=threads/nr_cpu
> >>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
> >>>> THP: enable / disable
> >>>> nr_task: 100%
> >>>>
> >>>> 1. Regressions:
> >>>> a) THP enabled:
> >>>> testcase base change head metric
> >>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
> >>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
> >>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
> >>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
> >>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
> >>>>
> >>>> b) THP disabled:
> >>>> testcase base change head metric
> >>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
> >>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
> >>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
> >>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
> >>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
> >>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
> >>>>
> >>>> 2. Improvements:
> >>>> a) THP enabled:
> >>>> testcase base change head metric
> >>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
> >>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
> >>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
> >>>>
> >>>> b) THP disabled:
> >>>> testcase base change head metric
> >>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
> >>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
> >>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
> >>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
> >>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
> >>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
> >>>>
> >>>> Notes: for above values in column "change", the higher value means that the related testcase result
> >>>> on head commit is better than that on base commit for this benchmark.
> >>>>
> >>>>
> >>>> Best regards
> >>>> Haiyan Song
> >>>>
> >>>> ________________________________________
> >>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> >>>> Sent: Thursday, May 17, 2018 7:06 PM
> >>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
> >>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> >>>> Subject: [PATCH v11 00/26] Speculative page faults
> >>>>
> >>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
> >>>> page fault without holding the mm semaphore [1].
> >>>>
> >>>> The idea is to try to handle user space page faults without holding the
> >>>> mmap_sem. This should allow better concurrency for massively threaded
> >>>> process since the page fault handler will not wait for other threads memory
> >>>> layout change to be done, assuming that this change is done in another part
> >>>> of the process's memory space. This type page fault is named speculative
> >>>> page fault. If the speculative page fault fails because of a concurrency is
> >>>> detected or because underlying PMD or PTE tables are not yet allocating, it
> >>>> is failing its processing and a classic page fault is then tried.
> >>>>
> >>>> The speculative page fault (SPF) has to look for the VMA matching the fault
> >>>> address without holding the mmap_sem, this is done by introducing a rwlock
> >>>> which protects the access to the mm_rb tree. Previously this was done using
> >>>> SRCU but it was introducing a lot of scheduling to process the VMA's
> >>>> freeing operation which was hitting the performance by 20% as reported by
> >>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
> >>>> limiting the locking contention to these operations which are expected to
> >>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
> >>>> our back a reference count is added and 2 services (get_vma() and
> >>>> put_vma()) are introduced to handle the reference count. Once a VMA is
> >>>> fetched from the RB tree using get_vma(), it must be later freed using
> >>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
> >>>> benchmark anymore.
> >>>>
> >>>> The VMA's attributes checked during the speculative page fault processing
> >>>> have to be protected against parallel changes. This is done by using a per
> >>>> VMA sequence lock. This sequence lock allows the speculative page fault
> >>>> handler to fast check for parallel changes in progress and to abort the
> >>>> speculative page fault in that case.
> >>>>
> >>>> Once the VMA has been found, the speculative page fault handler would check
> >>>> for the VMA's attributes to verify that the page fault has to be handled
> >>>> correctly or not. Thus, the VMA is protected through a sequence lock which
> >>>> allows fast detection of concurrent VMA changes. If such a change is
> >>>> detected, the speculative page fault is aborted and a *classic* page fault
> >>>> is tried. VMA sequence lockings are added when VMA attributes which are
> >>>> checked during the page fault are modified.
> >>>>
> >>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
> >>>> so once the page table is locked, the VMA is valid, so any other changes
> >>>> leading to touching this PTE will need to lock the page table, so no
> >>>> parallel change is possible at this time.
> >>>>
> >>>> The locking of the PTE is done with interrupts disabled, this allows
> >>>> checking for the PMD to ensure that there is not an ongoing collapsing
> >>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
> >>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
> >>>> valid at the time the PTE is locked, we have the guarantee that the
> >>>> collapsing operation will have to wait on the PTE lock to move forward.
> >>>> This allows the SPF handler to map the PTE safely. If the PMD value is
> >>>> different from the one recorded at the beginning of the SPF operation, the
> >>>> classic page fault handler will be called to handle the operation while
> >>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
> >>>> the lock is done using spin_trylock() to avoid dead lock when handling a
> >>>> page fault while a TLB invalidate is requested by another CPU holding the
> >>>> PTE.
> >>>>
> >>>> In pseudo code, this could be seen as:
> >>>> speculative_page_fault()
> >>>> {
> >>>> vma = get_vma()
> >>>> check vma sequence count
> >>>> check vma's support
> >>>> disable interrupt
> >>>> check pgd,p4d,...,pte
> >>>> save pmd and pte in vmf
> >>>> save vma sequence counter in vmf
> >>>> enable interrupt
> >>>> check vma sequence count
> >>>> handle_pte_fault(vma)
> >>>> ..
> >>>> page = alloc_page()
> >>>> pte_map_lock()
> >>>> disable interrupt
> >>>> abort if sequence counter has changed
> >>>> abort if pmd or pte has changed
> >>>> pte map and lock
> >>>> enable interrupt
> >>>> if abort
> >>>> free page
> >>>> abort
> >>>> ...
> >>>> }
> >>>>
> >>>> arch_fault_handler()
> >>>> {
> >>>> if (speculative_page_fault(&vma))
> >>>> goto done
> >>>> again:
> >>>> lock(mmap_sem)
> >>>> vma = find_vma();
> >>>> handle_pte_fault(vma);
> >>>> if retry
> >>>> unlock(mmap_sem)
> >>>> goto again;
> >>>> done:
> >>>> handle fault error
> >>>> }
> >>>>
> >>>> Support for THP is not done because when checking for the PMD, we can be
> >>>> confused by an in progress collapsing operation done by khugepaged. The
> >>>> issue is that pmd_none() could be true either if the PMD is not already
> >>>> populated or if the underlying PTE are in the way to be collapsed. So we
> >>>> cannot safely allocate a PMD if pmd_none() is true.
> >>>>
> >>>> This series add a new software performance event named 'speculative-faults'
> >>>> or 'spf'. It counts the number of successful page fault event handled
> >>>> speculatively. When recording 'faults,spf' events, the faults one is
> >>>> counting the total number of page fault events while 'spf' is only counting
> >>>> the part of the faults processed speculatively.
> >>>>
> >>>> There are some trace events introduced by this series. They allow
> >>>> identifying why the page faults were not processed speculatively. This
> >>>> doesn't take in account the faults generated by a monothreaded process
> >>>> which directly processed while holding the mmap_sem. This trace events are
> >>>> grouped in a system named 'pagefault', they are:
> >>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
> >>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
> >>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
> >>>> - pagefault:spf_vma_access : the VMA's access right are not respected
> >>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
> >>>> back.
> >>>>
> >>>> To record all the related events, the easier is to run perf with the
> >>>> following arguments :
> >>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
> >>>>
> >>>> There is also a dedicated vmstat counter showing the number of successful
> >>>> page fault handled speculatively. I can be seen this way:
> >>>> $ grep speculative_pgfault /proc/vmstat
> >>>>
> >>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
> >>>> on x86, PowerPC and arm64.
> >>>>
> >>>> ---------------------
> >>>> Real Workload results
> >>>>
> >>>> As mentioned in previous email, we did non official runs using a "popular
> >>>> in memory multithreaded database product" on 176 cores SMT8 Power system
> >>>> which showed a 30% improvements in the number of transaction processed per
> >>>> second. This run has been done on the v6 series, but changes introduced in
> >>>> this new version should not impact the performance boost seen.
> >>>>
> >>>> Here are the perf data captured during 2 of these runs on top of the v8
> >>>> series:
> >>>> vanilla spf
> >>>> faults 89.418 101.364 +13%
> >>>> spf n/a 97.989
> >>>>
> >>>> With the SPF kernel, most of the page fault were processed in a speculative
> >>>> way.
> >>>>
> >>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
> >>>> it a try on an android device. He reported that the application launch time
> >>>> was improved in average by 6%, and for large applications (~100 threads) by
> >>>> 20%.
> >>>>
> >>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
> >>>> MSM845 (8 cores) with 6GB (the less is better):
> >>>>
> >>>> Application 4.9 4.9+spf delta
> >>>> com.tencent.mm 416 389 -7%
> >>>> com.eg.android.AlipayGphone 1135 986 -13%
> >>>> com.tencent.mtt 455 454 0%
> >>>> com.qqgame.hlddz 1497 1409 -6%
> >>>> com.autonavi.minimap 711 701 -1%
> >>>> com.tencent.tmgp.sgame 788 748 -5%
> >>>> com.immomo.momo 501 487 -3%
> >>>> com.tencent.peng 2145 2112 -2%
> >>>> com.smile.gifmaker 491 461 -6%
> >>>> com.baidu.BaiduMap 479 366 -23%
> >>>> com.taobao.taobao 1341 1198 -11%
> >>>> com.baidu.searchbox 333 314 -6%
> >>>> com.tencent.mobileqq 394 384 -3%
> >>>> com.sina.weibo 907 906 0%
> >>>> com.youku.phone 816 731 -11%
> >>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
> >>>> com.UCMobile 415 411 -1%
> >>>> com.tencent.tmgp.ak 1464 1431 -2%
> >>>> com.tencent.qqmusic 336 329 -2%
> >>>> com.sankuai.meituan 1661 1302 -22%
> >>>> com.netease.cloudmusic 1193 1200 1%
> >>>> air.tv.douyu.android 4257 4152 -2%
> >>>>
> >>>> ------------------
> >>>> Benchmarks results
> >>>>
> >>>> Base kernel is v4.17.0-rc4-mm1
> >>>> SPF is BASE + this series
> >>>>
> >>>> Kernbench:
> >>>> ----------
> >>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
> >>>> kernel (kernel is build 5 times):
> >>>>
> >>>> Average Half load -j 8
> >>>> Run (std deviation)
> >>>> BASE SPF
> >>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
> >>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
> >>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
> >>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
> >>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
> >>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
> >>>>
> >>>> Average Optimal load -j 16
> >>>> Run (std deviation)
> >>>> BASE SPF
> >>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
> >>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
> >>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
> >>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
> >>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
> >>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
> >>>>
> >>>>
> >>>> During a run on the SPF, perf events were captured:
> >>>> Performance counter stats for '../kernbench -M':
> >>>> 526743764 faults
> >>>> 210 spf
> >>>> 3 pagefault:spf_vma_changed
> >>>> 0 pagefault:spf_vma_noanon
> >>>> 2278 pagefault:spf_vma_notsup
> >>>> 0 pagefault:spf_vma_access
> >>>> 0 pagefault:spf_pmd_changed
> >>>>
> >>>> Very few speculative page faults were recorded as most of the processes
> >>>> involved are monothreaded (sounds that on this architecture some threads
> >>>> were created during the kernel build processing).
> >>>>
> >>>> Here are the kerbench results on a 80 CPUs Power8 system:
> >>>>
> >>>> Average Half load -j 40
> >>>> Run (std deviation)
> >>>> BASE SPF
> >>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
> >>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
> >>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
> >>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
> >>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
> >>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
> >>>>
> >>>> Average Optimal load -j 80
> >>>> Run (std deviation)
> >>>> BASE SPF
> >>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
> >>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
> >>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
> >>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
> >>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
> >>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
> >>>>
> >>>> During a run on the SPF, perf events were captured:
> >>>> Performance counter stats for '../kernbench -M':
> >>>> 116730856 faults
> >>>> 0 spf
> >>>> 3 pagefault:spf_vma_changed
> >>>> 0 pagefault:spf_vma_noanon
> >>>> 476 pagefault:spf_vma_notsup
> >>>> 0 pagefault:spf_vma_access
> >>>> 0 pagefault:spf_pmd_changed
> >>>>
> >>>> Most of the processes involved are monothreaded so SPF is not activated but
> >>>> there is no impact on the performance.
> >>>>
> >>>> Ebizzy:
> >>>> -------
> >>>> The test is counting the number of records per second it can manage, the
> >>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
> >>>> consistent result I repeated the test 100 times and measure the average
> >>>> result. The number is the record processes per second, the higher is the
> >>>> best.
> >>>>
> >>>> BASE SPF delta
> >>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
> >>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
> >>>>
> >>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
> >>>> Performance counter stats for './ebizzy -mTt 16':
> >>>> 1706379 faults
> >>>> 1674599 spf
> >>>> 30588 pagefault:spf_vma_changed
> >>>> 0 pagefault:spf_vma_noanon
> >>>> 363 pagefault:spf_vma_notsup
> >>>> 0 pagefault:spf_vma_access
> >>>> 0 pagefault:spf_pmd_changed
> >>>>
> >>>> And the ones captured during a run on a 80 CPUs Power node:
> >>>> Performance counter stats for './ebizzy -mTt 80':
> >>>> 1874773 faults
> >>>> 1461153 spf
> >>>> 413293 pagefault:spf_vma_changed
> >>>> 0 pagefault:spf_vma_noanon
> >>>> 200 pagefault:spf_vma_notsup
> >>>> 0 pagefault:spf_vma_access
> >>>> 0 pagefault:spf_pmd_changed
> >>>>
> >>>> In ebizzy's case most of the page fault were handled in a speculative way,
> >>>> leading the ebizzy performance boost.
> >>>>
> >>>> ------------------
> >>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
> >>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
> >>>> and Minchan Kim, hopefully.
> >>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
> >>>> __do_page_fault().
> >>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
> >>>> instead
> >>>> of aborting the speculative page fault handling. Dropping the now
> >>>> useless
> >>>> trace event pagefault:spf_pte_lock.
> >>>> - No more try to reuse the fetched VMA during the speculative page fault
> >>>> handling when retrying is needed. This adds a lot of complexity and
> >>>> additional tests done didn't show a significant performance improvement.
> >>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
> >>>>
> >>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
> >>>> [2] https://patchwork.kernel.org/patch/9999687/
> >>>>
> >>>>
> >>>> Laurent Dufour (20):
> >>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
> >>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> >>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> >>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
> >>>> mm: make pte_unmap_same compatible with SPF
> >>>> mm: introduce INIT_VMA()
> >>>> mm: protect VMA modifications using VMA sequence count
> >>>> mm: protect mremap() against SPF hanlder
> >>>> mm: protect SPF handler against anon_vma changes
> >>>> mm: cache some VMA fields in the vm_fault structure
> >>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
> >>>> mm: introduce __lru_cache_add_active_or_unevictable
> >>>> mm: introduce __vm_normal_page()
> >>>> mm: introduce __page_add_new_anon_rmap()
> >>>> mm: protect mm_rb tree with a rwlock
> >>>> mm: adding speculative page fault failure trace events
> >>>> perf: add a speculative page fault sw event
> >>>> perf tools: add support for the SPF perf event
> >>>> mm: add speculative page fault vmstats
> >>>> powerpc/mm: add speculative page fault
> >>>>
> >>>> Mahendran Ganesh (2):
> >>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> >>>> arm64/mm: add speculative page fault
> >>>>
> >>>> Peter Zijlstra (4):
> >>>> mm: prepare for FAULT_FLAG_SPECULATIVE
> >>>> mm: VMA sequence count
> >>>> mm: provide speculative fault infrastructure
> >>>> x86/mm: add speculative pagefault handling
> >>>>
> >>>> arch/arm64/Kconfig | 1 +
> >>>> arch/arm64/mm/fault.c | 12 +
> >>>> arch/powerpc/Kconfig | 1 +
> >>>> arch/powerpc/mm/fault.c | 16 +
> >>>> arch/x86/Kconfig | 1 +
> >>>> arch/x86/mm/fault.c | 27 +-
> >>>> fs/exec.c | 2 +-
> >>>> fs/proc/task_mmu.c | 5 +-
> >>>> fs/userfaultfd.c | 17 +-
> >>>> include/linux/hugetlb_inline.h | 2 +-
> >>>> include/linux/migrate.h | 4 +-
> >>>> include/linux/mm.h | 136 +++++++-
> >>>> include/linux/mm_types.h | 7 +
> >>>> include/linux/pagemap.h | 4 +-
> >>>> include/linux/rmap.h | 12 +-
> >>>> include/linux/swap.h | 10 +-
> >>>> include/linux/vm_event_item.h | 3 +
> >>>> include/trace/events/pagefault.h | 80 +++++
> >>>> include/uapi/linux/perf_event.h | 1 +
> >>>> kernel/fork.c | 5 +-
> >>>> mm/Kconfig | 22 ++
> >>>> mm/huge_memory.c | 6 +-
> >>>> mm/hugetlb.c | 2 +
> >>>> mm/init-mm.c | 3 +
> >>>> mm/internal.h | 20 ++
> >>>> mm/khugepaged.c | 5 +
> >>>> mm/madvise.c | 6 +-
> >>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
> >>>> mm/mempolicy.c | 51 ++-
> >>>> mm/migrate.c | 6 +-
> >>>> mm/mlock.c | 13 +-
> >>>> mm/mmap.c | 229 ++++++++++---
> >>>> mm/mprotect.c | 4 +-
> >>>> mm/mremap.c | 13 +
> >>>> mm/nommu.c | 2 +-
> >>>> mm/rmap.c | 5 +-
> >>>> mm/swap.c | 6 +-
> >>>> mm/swap_state.c | 8 +-
> >>>> mm/vmstat.c | 5 +-
> >>>> tools/include/uapi/linux/perf_event.h | 1 +
> >>>> tools/perf/util/evsel.c | 1 +
> >>>> tools/perf/util/parse-events.c | 4 +
> >>>> tools/perf/util/parse-events.l | 1 +
> >>>> tools/perf/util/python.c | 1 +
> >>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
> >>>> create mode 100644 include/trace/events/pagefault.h
> >>>>
> >>>> --
> >>>> 2.7.4
> >>>>
> >>>>
> >>>
> >>
> >
>
[-- Attachment #2: compare-result.txt --]
[-- Type: text/plain, Size: 185207 bytes --]
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/always/page_fault3/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
44:3 -13% 43:3 perf-profile.calltrace.cycles-pp.error_entry
22:3 -6% 22:3 perf-profile.calltrace.cycles-pp.sync_regs.error_entry
44:3 -13% 44:3 perf-profile.children.cycles-pp.error_entry
21:3 -7% 21:3 perf-profile.self.cycles-pp.error_entry
%stddev %change %stddev
\ | \
10519 +- 3% -20.5% 8368 +- 6% will-it-scale.per_thread_ops
118098 +11.2% 131287 +- 2% will-it-scale.time.involuntary_context_switches
6.084e+08 +- 3% -20.4% 4.845e+08 +- 6% will-it-scale.time.minor_page_faults
7467 +5.0% 7841 will-it-scale.time.percent_of_cpu_this_job_got
44922 +5.0% 47176 will-it-scale.time.system_time
7126337 +- 3% -15.4% 6025689 +- 6% will-it-scale.time.voluntary_context_switches
91905646 -1.3% 90673935 will-it-scale.workload
27.15 +- 6% -8.7% 24.80 +- 10% boot-time.boot
2516213 +- 6% +8.3% 2726303 interrupts.CAL:Function_call_interrupts
388.00 +- 9% +60.2% 621.67 +- 20% irq_exception_noise.softirq_nr
11.28 +- 2% -1.9 9.37 +- 4% mpstat.cpu.idle%
10065 +-140% +243.4% 34559 +- 4% numa-numastat.node0.other_node
18739 -11.6% 16573 +- 3% uptime.idle
29406 +- 2% -11.8% 25929 +- 5% vmstat.system.cs
329614 +- 8% +17.0% 385618 +- 10% meminfo.DirectMap4k
237851 +21.2% 288160 +- 5% meminfo.Inactive
237615 +21.2% 287924 +- 5% meminfo.Inactive(anon)
7917847 -10.7% 7071860 softirqs.RCU
4784181 +- 3% -14.5% 4089039 +- 4% softirqs.SCHED
45666107 +- 7% +12.9% 51535472 +- 3% softirqs.TIMER
2.617e+09 +- 2% -13.9% 2.253e+09 +- 6% cpuidle.C1E.time
6688774 +- 2% -12.8% 5835101 +- 5% cpuidle.C1E.usage
1.022e+10 +- 2% -18.0% 8.376e+09 +- 3% cpuidle.C6.time
13440993 +- 2% -16.3% 11243794 +- 4% cpuidle.C6.usage
54781 +- 16% +37.5% 75347 +- 12% numa-meminfo.node0.Inactive
54705 +- 16% +37.7% 75347 +- 12% numa-meminfo.node0.Inactive(anon)
52522 +35.0% 70886 +- 6% numa-meminfo.node2.Inactive
52443 +34.7% 70653 +- 6% numa-meminfo.node2.Inactive(anon)
31046 +- 6% +30.3% 40457 +- 11% numa-meminfo.node2.SReclaimable
58563 +21.1% 70945 +- 6% proc-vmstat.nr_inactive_anon
58564 +21.1% 70947 +- 6% proc-vmstat.nr_zone_inactive_anon
69701118 -1.2% 68842151 proc-vmstat.pgalloc_normal
2.765e+10 -1.3% 2.729e+10 proc-vmstat.pgfault
69330418 -1.2% 68466824 proc-vmstat.pgfree
118098 +11.2% 131287 +- 2% time.involuntary_context_switches
6.084e+08 +- 3% -20.4% 4.845e+08 +- 6% time.minor_page_faults
7467 +5.0% 7841 time.percent_of_cpu_this_job_got
44922 +5.0% 47176 time.system_time
7126337 +- 3% -15.4% 6025689 +- 6% time.voluntary_context_switches
13653 +- 16% +33.5% 18225 +- 12% numa-vmstat.node0.nr_inactive_anon
13651 +- 16% +33.5% 18224 +- 12% numa-vmstat.node0.nr_zone_inactive_anon
13069 +- 3% +30.1% 17001 +- 4% numa-vmstat.node2.nr_inactive_anon
134.67 +- 42% -49.5% 68.00 +- 31% numa-vmstat.node2.nr_mlock
7758 +- 6% +30.4% 10112 +- 11% numa-vmstat.node2.nr_slab_reclaimable
13066 +- 3% +30.1% 16998 +- 4% numa-vmstat.node2.nr_zone_inactive_anon
1039 +- 11% -17.5% 857.33 slabinfo.Acpi-ParseExt.active_objs
1039 +- 11% -17.5% 857.33 slabinfo.Acpi-ParseExt.num_objs
2566 +- 6% -8.8% 2340 +- 5% slabinfo.biovec-64.active_objs
2566 +- 6% -8.8% 2340 +- 5% slabinfo.biovec-64.num_objs
898.33 +- 3% -9.5% 813.33 +- 3% slabinfo.kmem_cache_node.active_objs
1066 +- 2% -8.0% 981.33 +- 3% slabinfo.kmem_cache_node.num_objs
1940 +2.3% 1984 turbostat.Avg_MHz
6679037 +- 2% -12.7% 5830270 +- 5% turbostat.C1E
2.25 +- 2% -0.3 1.94 +- 6% turbostat.C1E%
13418115 -16.3% 11234510 +- 4% turbostat.C6
8.75 +- 2% -1.6 7.18 +- 3% turbostat.C6%
5.99 +- 2% -14.4% 5.13 +- 4% turbostat.CPU%c1
5.01 +- 3% -20.1% 4.00 +- 4% turbostat.CPU%c6
1.77 +- 3% -34.7% 1.15 turbostat.Pkg%pc2
1.378e+13 +1.2% 1.394e+13 perf-stat.branch-instructions
0.98 -0.0 0.94 perf-stat.branch-miss-rate%
1.344e+11 -2.3% 1.313e+11 perf-stat.branch-misses
1.076e+11 -1.8% 1.057e+11 perf-stat.cache-misses
2.258e+11 -2.1% 2.21e+11 perf-stat.cache-references
17788064 +- 2% -11.9% 15674207 +- 6% perf-stat.context-switches
2.241e+14 +2.4% 2.294e+14 perf-stat.cpu-cycles
1.929e+13 +2.2% 1.971e+13 perf-stat.dTLB-loads
4.01 -0.2 3.83 perf-stat.dTLB-store-miss-rate%
4.519e+11 -1.3% 4.461e+11 perf-stat.dTLB-store-misses
1.082e+13 +3.6% 1.121e+13 perf-stat.dTLB-stores
3.02e+10 +23.2% 3.721e+10 +- 3% perf-stat.iTLB-load-misses
2.721e+08 +- 8% -8.8% 2.481e+08 +- 3% perf-stat.iTLB-loads
6.985e+13 +1.8% 7.111e+13 perf-stat.instructions
2313 -17.2% 1914 +- 3% perf-stat.instructions-per-iTLB-miss
2.764e+10 -1.3% 2.729e+10 perf-stat.minor-faults
1.421e+09 +- 2% -16.4% 1.188e+09 +- 9% perf-stat.node-load-misses
1.538e+10 -9.3% 1.395e+10 perf-stat.node-loads
9.75 +1.4 11.10 perf-stat.node-store-miss-rate%
3.012e+09 +14.1% 3.437e+09 perf-stat.node-store-misses
2.789e+10 -1.3% 2.753e+10 perf-stat.node-stores
2.764e+10 -1.3% 2.729e+10 perf-stat.page-faults
760059 +3.2% 784235 perf-stat.path-length
193545 +- 25% -57.8% 81757 +- 46% sched_debug.cfs_rq:/.MIN_vruntime.avg
26516863 +- 19% -49.7% 13338070 +- 33% sched_debug.cfs_rq:/.MIN_vruntime.max
2202271 +- 21% -53.2% 1029581 +- 38% sched_debug.cfs_rq:/.MIN_vruntime.stddev
193545 +- 25% -57.8% 81757 +- 46% sched_debug.cfs_rq:/.max_vruntime.avg
26516863 +- 19% -49.7% 13338070 +- 33% sched_debug.cfs_rq:/.max_vruntime.max
2202271 +- 21% -53.2% 1029581 +- 38% sched_debug.cfs_rq:/.max_vruntime.stddev
0.32 +- 70% +253.2% 1.14 +- 54% sched_debug.cfs_rq:/.removed.load_avg.avg
4.44 +- 70% +120.7% 9.80 +- 27% sched_debug.cfs_rq:/.removed.load_avg.stddev
14.90 +- 70% +251.0% 52.31 +- 53% sched_debug.cfs_rq:/.removed.runnable_sum.avg
205.71 +- 70% +119.5% 451.60 +- 27% sched_debug.cfs_rq:/.removed.runnable_sum.stddev
0.16 +- 70% +237.9% 0.54 +- 50% sched_debug.cfs_rq:/.removed.util_avg.avg
2.23 +- 70% +114.2% 4.77 +- 24% sched_debug.cfs_rq:/.removed.util_avg.stddev
573.70 +- 5% -9.7% 518.06 +- 6% sched_debug.cfs_rq:/.util_avg.min
114.87 +- 8% +14.1% 131.04 +- 10% sched_debug.cfs_rq:/.util_est_enqueued.avg
64.42 +- 54% -63.9% 23.27 +- 68% sched_debug.cpu.cpu_load[1].max
5.05 +- 48% -55.2% 2.26 +- 51% sched_debug.cpu.cpu_load[1].stddev
57.58 +- 59% -60.3% 22.88 +- 70% sched_debug.cpu.cpu_load[2].max
21019 +- 3% -15.1% 17841 +- 6% sched_debug.cpu.nr_switches.min
20797 +- 3% -15.0% 17670 +- 6% sched_debug.cpu.sched_count.min
10287 +- 3% -15.1% 8736 +- 6% sched_debug.cpu.sched_goidle.avg
13693 +- 2% -10.7% 12233 +- 5% sched_debug.cpu.sched_goidle.max
9976 +- 3% -16.0% 8381 +- 7% sched_debug.cpu.sched_goidle.min
0.00 +- 26% +98.9% 0.00 +- 28% sched_debug.rt_rq:/.rt_time.min
4230 +-141% -100.0% 0.00 latency_stats.avg.trace_module_notify.notifier_call_chain.blocking_notifier_call_chain.do_init_module.load_module.__do_sys_finit_module.do_syscall_64.entry_SYSCALL_64_after_hwframe
28498 +-141% -100.0% 0.00 latency_stats.avg.perf_event_alloc.__do_sys_perf_event_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
4065 +-138% -92.2% 315.33 +- 91% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup_revalidate.lookup_fast.walk_component.link_path_walk.path_lookupat.filename_lookup
0.00 +3.6e+105% 3641 +-141% latency_stats.avg.down.console_lock.console_device.tty_lookup_driver.tty_open.chrdev_open.do_dentry_open.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +2.5e+106% 25040 +-141% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +3.4e+106% 34015 +-141% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_get_acl.get_acl.posix_acl_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open
0.00 +4.8e+106% 47686 +-141% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_do_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open.do_syscall_64
4230 +-141% -100.0% 0.00 latency_stats.max.trace_module_notify.notifier_call_chain.blocking_notifier_call_chain.do_init_module.load_module.__do_sys_finit_module.do_syscall_64.entry_SYSCALL_64_after_hwframe
28498 +-141% -100.0% 0.00 latency_stats.max.perf_event_alloc.__do_sys_perf_event_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
4065 +-138% -92.2% 315.33 +- 91% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup_revalidate.lookup_fast.walk_component.link_path_walk.path_lookupat.filename_lookup
4254 +-134% -88.0% 511.67 +- 90% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
43093 +- 35% +76.6% 76099 +-115% latency_stats.max.blk_execute_rq.scsi_execute.ioctl_internal_command.scsi_set_medium_removal.cdrom_release.[cdrom].sr_block_release.[sr_mod].__blkdev_put.blkdev_close.__fput.task_work_run.exit_to_usermode_loop.do_syscall_64
24139 +- 70% +228.5% 79285 +-105% latency_stats.max.blk_execute_rq.scsi_execute.scsi_test_unit_ready.sr_check_events.[sr_mod].cdrom_check_events.[cdrom].sr_block_check_events.[sr_mod].disk_check_events.disk_clear_events.check_disk_change.sr_block_open.[sr_mod].__blkdev_get.blkdev_get
0.00 +3.6e+105% 3641 +-141% latency_stats.max.down.console_lock.console_device.tty_lookup_driver.tty_open.chrdev_open.do_dentry_open.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +2.5e+106% 25040 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +3.4e+106% 34015 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_get_acl.get_acl.posix_acl_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open
0.00 +6.5e+106% 64518 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_do_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open.do_syscall_64
4230 +-141% -100.0% 0.00 latency_stats.sum.trace_module_notify.notifier_call_chain.blocking_notifier_call_chain.do_init_module.load_module.__do_sys_finit_module.do_syscall_64.entry_SYSCALL_64_after_hwframe
28498 +-141% -100.0% 0.00 latency_stats.sum.perf_event_alloc.__do_sys_perf_event_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
4065 +-138% -92.2% 315.33 +- 91% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup_revalidate.lookup_fast.walk_component.link_path_walk.path_lookupat.filename_lookup
57884 +- 9% +47.3% 85264 +-118% latency_stats.sum.blk_execute_rq.scsi_execute.ioctl_internal_command.scsi_set_medium_removal.cdrom_release.[cdrom].sr_block_release.[sr_mod].__blkdev_put.blkdev_close.__fput.task_work_run.exit_to_usermode_loop.do_syscall_64
0.00 +3.6e+105% 3641 +-141% latency_stats.sum.down.console_lock.console_device.tty_lookup_driver.tty_open.chrdev_open.do_dentry_open.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +2.5e+106% 25040 +-141% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +3.4e+106% 34015 +-141% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_get_acl.get_acl.posix_acl_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open
0.00 +9.5e+106% 95373 +-141% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_do_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open.do_syscall_64
11.70 -11.7 0.00 perf-profile.calltrace.cycles-pp.__do_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
11.52 -11.5 0.00 perf-profile.calltrace.cycles-pp.shmem_fault.__do_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
10.44 -10.4 0.00 perf-profile.calltrace.cycles-pp.shmem_getpage_gfp.shmem_fault.__do_fault.__handle_mm_fault.handle_mm_fault
9.83 -9.8 0.00 perf-profile.calltrace.cycles-pp.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault.__handle_mm_fault
9.55 -9.5 0.00 perf-profile.calltrace.cycles-pp.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
9.35 -9.3 0.00 perf-profile.calltrace.cycles-pp.alloc_set_pte.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
6.81 -6.8 0.00 perf-profile.calltrace.cycles-pp.page_add_file_rmap.alloc_set_pte.finish_fault.__handle_mm_fault.handle_mm_fault
7.71 -0.3 7.45 perf-profile.calltrace.cycles-pp.find_get_entry.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault
0.59 +- 7% -0.2 0.35 +- 70% perf-profile.calltrace.cycles-pp.smp_apic_timer_interrupt.apic_timer_interrupt.__do_page_fault.do_page_fault.page_fault
0.59 +- 7% -0.2 0.35 +- 70% perf-profile.calltrace.cycles-pp.apic_timer_interrupt.__do_page_fault.do_page_fault.page_fault
10.41 -0.2 10.24 perf-profile.calltrace.cycles-pp.native_irq_return_iret
7.68 -0.1 7.60 perf-profile.calltrace.cycles-pp.swapgs_restore_regs_and_return_to_usermode
0.76 -0.1 0.70 perf-profile.calltrace.cycles-pp.down_read_trylock.__do_page_fault.do_page_fault.page_fault
1.38 -0.0 1.34 perf-profile.calltrace.cycles-pp.do_page_fault
1.05 -0.0 1.02 perf-profile.calltrace.cycles-pp.trace_graph_entry.do_page_fault
0.92 +0.0 0.94 perf-profile.calltrace.cycles-pp.find_vma.__do_page_fault.do_page_fault.page_fault
0.91 +0.0 0.93 perf-profile.calltrace.cycles-pp.vmacache_find.find_vma.__do_page_fault.do_page_fault.page_fault
0.65 +0.0 0.67 perf-profile.calltrace.cycles-pp.set_page_dirty.unmap_page_range.unmap_vmas.unmap_region.do_munmap
0.62 +0.0 0.66 perf-profile.calltrace.cycles-pp.page_mapping.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault
4.15 +0.1 4.27 perf-profile.calltrace.cycles-pp.page_remove_rmap.unmap_page_range.unmap_vmas.unmap_region.do_munmap
10.17 +0.2 10.39 perf-profile.calltrace.cycles-pp.munmap
9.56 +0.2 9.78 perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.munmap
9.56 +0.2 9.78 perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.munmap
9.56 +0.2 9.78 perf-profile.calltrace.cycles-pp.unmap_region.do_munmap.vm_munmap.__x64_sys_munmap.do_syscall_64
9.54 +0.2 9.76 perf-profile.calltrace.cycles-pp.unmap_page_range.unmap_vmas.unmap_region.do_munmap.vm_munmap
9.54 +0.2 9.76 perf-profile.calltrace.cycles-pp.unmap_vmas.unmap_region.do_munmap.vm_munmap.__x64_sys_munmap
9.56 +0.2 9.78 perf-profile.calltrace.cycles-pp.do_munmap.vm_munmap.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe
9.56 +0.2 9.78 perf-profile.calltrace.cycles-pp.vm_munmap.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe.munmap
9.56 +0.2 9.78 perf-profile.calltrace.cycles-pp.__x64_sys_munmap.do_syscall_64.entry_SYSCALL_64_after_hwframe.munmap
0.00 +0.6 0.56 +- 2% perf-profile.calltrace.cycles-pp.lock_page_memcg.page_add_file_rmap.alloc_set_pte.finish_fault.handle_pte_fault
0.00 +0.6 0.59 perf-profile.calltrace.cycles-pp.page_mapping.set_page_dirty.fault_dirty_shared_page.handle_pte_fault.__handle_mm_fault
0.00 +0.6 0.60 perf-profile.calltrace.cycles-pp.current_time.file_update_time.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +0.7 0.68 perf-profile.calltrace.cycles-pp.___might_sleep.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault
0.00 +0.7 0.74 perf-profile.calltrace.cycles-pp.unlock_page.fault_dirty_shared_page.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +0.8 0.80 perf-profile.calltrace.cycles-pp.set_page_dirty.fault_dirty_shared_page.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +0.9 0.88 perf-profile.calltrace.cycles-pp._raw_spin_lock.pte_map_lock.alloc_set_pte.finish_fault.handle_pte_fault
0.00 +0.9 0.91 perf-profile.calltrace.cycles-pp.__set_page_dirty_no_writeback.fault_dirty_shared_page.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +1.3 1.27 perf-profile.calltrace.cycles-pp.pte_map_lock.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault
0.00 +1.3 1.30 perf-profile.calltrace.cycles-pp.file_update_time.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +2.8 2.76 perf-profile.calltrace.cycles-pp.fault_dirty_shared_page.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +6.8 6.81 perf-profile.calltrace.cycles-pp.page_add_file_rmap.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault
0.00 +9.4 9.39 perf-profile.calltrace.cycles-pp.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +9.6 9.59 perf-profile.calltrace.cycles-pp.finish_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +9.8 9.77 perf-profile.calltrace.cycles-pp.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault.handle_pte_fault
0.00 +10.4 10.37 perf-profile.calltrace.cycles-pp.shmem_getpage_gfp.shmem_fault.__do_fault.handle_pte_fault.__handle_mm_fault
0.00 +11.5 11.46 perf-profile.calltrace.cycles-pp.shmem_fault.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +11.6 11.60 perf-profile.calltrace.cycles-pp.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +26.6 26.62 perf-profile.calltrace.cycles-pp.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
7.88 -0.3 7.61 perf-profile.children.cycles-pp.find_get_entry
1.34 +- 8% -0.2 1.16 +- 2% perf-profile.children.cycles-pp.hrtimer_interrupt
10.41 -0.2 10.24 perf-profile.children.cycles-pp.native_irq_return_iret
0.38 +- 28% -0.1 0.26 +- 4% perf-profile.children.cycles-pp.tick_sched_timer
11.80 -0.1 11.68 perf-profile.children.cycles-pp.__do_fault
0.55 +- 15% -0.1 0.43 +- 2% perf-profile.children.cycles-pp.__hrtimer_run_queues
0.60 -0.1 0.51 perf-profile.children.cycles-pp.pmd_devmap_trans_unstable
0.38 +- 13% -0.1 0.29 +- 4% perf-profile.children.cycles-pp.ktime_get
7.68 -0.1 7.60 perf-profile.children.cycles-pp.swapgs_restore_regs_and_return_to_usermode
5.18 -0.1 5.12 perf-profile.children.cycles-pp.trace_graph_entry
0.79 -0.1 0.73 perf-profile.children.cycles-pp.down_read_trylock
7.83 -0.1 7.76 perf-profile.children.cycles-pp.sync_regs
3.01 -0.1 2.94 perf-profile.children.cycles-pp.fault_dirty_shared_page
1.02 -0.1 0.96 perf-profile.children.cycles-pp._raw_spin_lock
4.66 -0.1 4.61 perf-profile.children.cycles-pp.prepare_ftrace_return
0.37 +- 8% -0.1 0.32 +- 3% perf-profile.children.cycles-pp.current_kernel_time64
5.26 -0.1 5.21 perf-profile.children.cycles-pp.ftrace_graph_caller
0.66 +- 5% -0.1 0.61 perf-profile.children.cycles-pp.current_time
0.18 +- 5% -0.0 0.15 +- 3% perf-profile.children.cycles-pp.update_process_times
0.27 -0.0 0.26 perf-profile.children.cycles-pp._cond_resched
0.16 -0.0 0.15 +- 3% perf-profile.children.cycles-pp.rcu_all_qs
0.94 +0.0 0.95 perf-profile.children.cycles-pp.vmacache_find
0.48 +0.0 0.50 perf-profile.children.cycles-pp.__mod_node_page_state
0.17 +0.0 0.19 +- 2% perf-profile.children.cycles-pp.__unlock_page_memcg
1.07 +0.0 1.10 perf-profile.children.cycles-pp.find_vma
0.79 +- 3% +0.1 0.86 +- 2% perf-profile.children.cycles-pp.lock_page_memcg
4.29 +0.1 4.40 perf-profile.children.cycles-pp.page_remove_rmap
1.39 +- 2% +0.1 1.52 perf-profile.children.cycles-pp.file_update_time
0.00 +0.2 0.16 perf-profile.children.cycles-pp.__vm_normal_page
9.63 +0.2 9.84 perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
9.63 +0.2 9.84 perf-profile.children.cycles-pp.do_syscall_64
9.63 +0.2 9.84 perf-profile.children.cycles-pp.unmap_page_range
10.17 +0.2 10.39 perf-profile.children.cycles-pp.munmap
9.56 +0.2 9.78 perf-profile.children.cycles-pp.unmap_region
9.56 +0.2 9.78 perf-profile.children.cycles-pp.do_munmap
9.56 +0.2 9.78 perf-profile.children.cycles-pp.vm_munmap
9.56 +0.2 9.78 perf-profile.children.cycles-pp.__x64_sys_munmap
9.54 +0.2 9.77 perf-profile.children.cycles-pp.unmap_vmas
1.01 +0.2 1.25 perf-profile.children.cycles-pp.___might_sleep
0.00 +1.6 1.59 perf-profile.children.cycles-pp.pte_map_lock
0.00 +26.9 26.89 perf-profile.children.cycles-pp.handle_pte_fault
4.25 -1.0 3.24 perf-profile.self.cycles-pp.__handle_mm_fault
1.42 -0.3 1.11 perf-profile.self.cycles-pp.alloc_set_pte
4.87 -0.3 4.59 perf-profile.self.cycles-pp.find_get_entry
10.41 -0.2 10.24 perf-profile.self.cycles-pp.native_irq_return_iret
0.37 +- 13% -0.1 0.28 +- 4% perf-profile.self.cycles-pp.ktime_get
0.60 -0.1 0.51 perf-profile.self.cycles-pp.pmd_devmap_trans_unstable
7.50 -0.1 7.42 perf-profile.self.cycles-pp.swapgs_restore_regs_and_return_to_usermode
7.83 -0.1 7.76 perf-profile.self.cycles-pp.sync_regs
4.85 -0.1 4.79 perf-profile.self.cycles-pp.trace_graph_entry
1.01 -0.1 0.95 perf-profile.self.cycles-pp._raw_spin_lock
0.78 -0.1 0.73 perf-profile.self.cycles-pp.down_read_trylock
0.36 +- 9% -0.1 0.31 +- 4% perf-profile.self.cycles-pp.current_kernel_time64
0.28 -0.0 0.23 +- 2% perf-profile.self.cycles-pp.__do_fault
1.04 -0.0 1.00 perf-profile.self.cycles-pp.find_lock_entry
0.30 -0.0 0.28 +- 3% perf-profile.self.cycles-pp.fault_dirty_shared_page
0.70 -0.0 0.67 perf-profile.self.cycles-pp.prepare_ftrace_return
0.44 -0.0 0.42 perf-profile.self.cycles-pp.do_page_fault
0.16 -0.0 0.14 perf-profile.self.cycles-pp.rcu_all_qs
0.78 -0.0 0.77 perf-profile.self.cycles-pp.shmem_getpage_gfp
0.20 -0.0 0.19 perf-profile.self.cycles-pp._cond_resched
0.50 +0.0 0.51 perf-profile.self.cycles-pp.set_page_dirty
0.93 +0.0 0.95 perf-profile.self.cycles-pp.vmacache_find
0.36 +- 2% +0.0 0.38 perf-profile.self.cycles-pp.__might_sleep
0.47 +0.0 0.50 perf-profile.self.cycles-pp.__mod_node_page_state
0.17 +0.0 0.19 +- 2% perf-profile.self.cycles-pp.__unlock_page_memcg
2.34 +0.0 2.38 perf-profile.self.cycles-pp.unmap_page_range
0.78 +- 3% +0.1 0.85 +- 2% perf-profile.self.cycles-pp.lock_page_memcg
2.17 +0.1 2.24 perf-profile.self.cycles-pp.__do_page_fault
0.00 +0.2 0.16 +- 3% perf-profile.self.cycles-pp.__vm_normal_page
1.00 +0.2 1.24 perf-profile.self.cycles-pp.___might_sleep
0.00 +0.7 0.70 perf-profile.self.cycles-pp.pte_map_lock
0.00 +1.4 1.42 +- 2% perf-profile.self.cycles-pp.handle_pte_fault
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/never/context_switch1/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
:3 33% 1:3 dmesg.WARNING:at#for_ip_interrupt_entry/0x
2:3 -67% :3 kmsg.pstore:crypto_comp_decompress_failed,ret=
2:3 -67% :3 kmsg.pstore:decompression_failed
%stddev %change %stddev
\ | \
224431 -1.3% 221567 will-it-scale.per_process_ops
237006 -2.2% 231907 will-it-scale.per_thread_ops
1.601e+09 +- 29% -46.9% 8.501e+08 +- 12% will-it-scale.time.involuntary_context_switches
5429 -1.6% 5344 will-it-scale.time.user_time
88596221 -1.7% 87067269 will-it-scale.workload
6863 +- 6% -9.7% 6200 boot-time.idle
144908 +- 40% -66.8% 48173 +- 93% meminfo.CmaFree
0.00 +- 70% +0.0 0.00 mpstat.cpu.iowait%
448336 +- 14% -34.8% 292125 +- 3% turbostat.C1
7684 +- 6% -9.5% 6957 uptime.idle
1.601e+09 +- 29% -46.9% 8.501e+08 +- 12% time.involuntary_context_switches
5429 -1.6% 5344 time.user_time
44013162 -1.7% 43243125 vmstat.system.cs
207684 -1.1% 205485 vmstat.system.in
2217033 +- 15% -15.8% 1866876 +- 2% cpuidle.C1.time
451218 +- 14% -34.7% 294841 +- 2% cpuidle.C1.usage
24839 +- 10% -19.9% 19896 cpuidle.POLL.time
7656 +- 11% -38.9% 4676 +- 8% cpuidle.POLL.usage
5.48 +- 49% -67.3% 1.79 +-100% irq_exception_noise.__do_page_fault.95th
9.46 +- 21% -58.2% 3.95 +- 64% irq_exception_noise.__do_page_fault.99th
35.67 +- 8% +1394.4% 533.00 +- 96% irq_exception_noise.irq_nr
52109 +- 3% -16.0% 43784 +- 4% irq_exception_noise.softirq_time
36226 +- 40% -66.7% 12048 +- 93% proc-vmstat.nr_free_cma
25916 -1.0% 25659 proc-vmstat.nr_slab_reclaimable
16279 +- 8% +2646.1% 447053 +- 82% proc-vmstat.pgalloc_movable
2231117 -18.4% 1820828 +- 20% proc-vmstat.pgalloc_normal
1109316 +- 46% -86.9% 145207 +-109% numa-numastat.node1.local_node
1114700 +- 45% -84.5% 172877 +- 85% numa-numastat.node1.numa_hit
5523 +-140% +402.8% 27768 +- 39% numa-numastat.node1.other_node
29013 +- 29% +3048.1% 913379 +- 73% numa-numastat.node3.local_node
65032 +- 13% +1335.1% 933270 +- 70% numa-numastat.node3.numa_hit
36018 -44.8% 19897 +- 75% numa-numastat.node3.other_node
12.79 +- 21% +7739.1% 1002 +-136% sched_debug.cpu.cpu_load[1].max
1.82 +- 10% +3901.1% 72.92 +-135% sched_debug.cpu.cpu_load[1].stddev
1.71 +- 4% +5055.8% 88.08 +-137% sched_debug.cpu.cpu_load[2].stddev
12.33 +- 23% +9061.9% 1129 +-139% sched_debug.cpu.cpu_load[3].max
1.78 +- 10% +4514.8% 82.18 +-137% sched_debug.cpu.cpu_load[3].stddev
4692 +- 72% +154.5% 11945 +- 29% sched_debug.cpu.max_idle_balance_cost.stddev
23979 -8.3% 21983 slabinfo.kmalloc-96.active_objs
1358 +- 6% -17.9% 1114 +- 3% slabinfo.nsproxy.active_objs
1358 +- 6% -17.9% 1114 +- 3% slabinfo.nsproxy.num_objs
15229 +12.4% 17119 slabinfo.pde_opener.active_objs
15229 +12.4% 17119 slabinfo.pde_opener.num_objs
59541 +- 8% -10.1% 53537 +- 8% slabinfo.vm_area_struct.active_objs
59612 +- 8% -10.1% 53604 +- 8% slabinfo.vm_area_struct.num_objs
4.163e+13 -1.4% 4.105e+13 perf-stat.branch-instructions
6.537e+11 -1.2% 6.459e+11 perf-stat.branch-misses
2.667e+10 -1.7% 2.621e+10 perf-stat.context-switches
1.21 +1.3% 1.22 perf-stat.cpi
150508 -9.8% 135825 +- 3% perf-stat.cpu-migrations
5.75 +- 33% +5.4 11.11 +- 26% perf-stat.iTLB-load-miss-rate%
3.619e+09 +- 36% +100.9% 7.272e+09 +- 30% perf-stat.iTLB-load-misses
2.089e+14 -1.3% 2.062e+14 perf-stat.instructions
64607 +- 29% -50.5% 31964 +- 37% perf-stat.instructions-per-iTLB-miss
0.83 -1.3% 0.82 perf-stat.ipc
3972 +- 4% -14.7% 3388 +- 8% numa-meminfo.node0.PageTables
207919 +- 25% -57.2% 88989 +- 74% numa-meminfo.node1.Active
207715 +- 26% -57.3% 88785 +- 74% numa-meminfo.node1.Active(anon)
356529 -34.3% 234069 +- 2% numa-meminfo.node1.FilePages
789129 +- 5% -19.8% 633161 +- 12% numa-meminfo.node1.MemUsed
34777 +- 8% -48.2% 18010 +- 30% numa-meminfo.node1.SReclaimable
69641 +- 4% -20.7% 55250 +- 12% numa-meminfo.node1.SUnreclaim
125526 +- 4% -96.3% 4602 +- 41% numa-meminfo.node1.Shmem
104419 -29.8% 73261 +- 16% numa-meminfo.node1.Slab
103661 +- 17% -72.0% 29029 +- 99% numa-meminfo.node2.Active
103661 +- 17% -72.2% 28829 +-101% numa-meminfo.node2.Active(anon)
103564 +- 18% -72.0% 29007 +-100% numa-meminfo.node2.AnonPages
671654 +- 7% -14.6% 573598 +- 4% numa-meminfo.node2.MemUsed
44206 +-127% +301.4% 177465 +- 42% numa-meminfo.node3.Active
44206 +-127% +301.0% 177263 +- 42% numa-meminfo.node3.Active(anon)
8738 +12.2% 9805 +- 8% numa-meminfo.node3.KernelStack
603605 +- 9% +27.8% 771554 +- 14% numa-meminfo.node3.MemUsed
14438 +- 6% +122.9% 32181 +- 42% numa-meminfo.node3.SReclaimable
2786 +-137% +3302.0% 94792 +- 71% numa-meminfo.node3.Shmem
71461 +- 7% +45.2% 103771 +- 29% numa-meminfo.node3.Slab
247197 +- 4% -7.8% 227843 numa-meminfo.node3.Unevictable
991.67 +- 4% -14.7% 846.00 +- 8% numa-vmstat.node0.nr_page_table_pages
51926 +- 26% -57.3% 22196 +- 74% numa-vmstat.node1.nr_active_anon
89137 -34.4% 58516 +- 2% numa-vmstat.node1.nr_file_pages
1679 +- 5% -10.8% 1498 +- 4% numa-vmstat.node1.nr_mapped
31386 +- 4% -96.3% 1150 +- 41% numa-vmstat.node1.nr_shmem
8694 +- 8% -48.2% 4502 +- 30% numa-vmstat.node1.nr_slab_reclaimable
17410 +- 4% -20.7% 13812 +- 12% numa-vmstat.node1.nr_slab_unreclaimable
51926 +- 26% -57.3% 22196 +- 74% numa-vmstat.node1.nr_zone_active_anon
1037174 +- 24% -57.0% 446205 +- 35% numa-vmstat.node1.numa_hit
961611 +- 26% -65.8% 328687 +- 50% numa-vmstat.node1.numa_local
75563 +- 44% +55.5% 117517 +- 9% numa-vmstat.node1.numa_other
25914 +- 17% -72.2% 7206 +-101% numa-vmstat.node2.nr_active_anon
25891 +- 18% -72.0% 7251 +-100% numa-vmstat.node2.nr_anon_pages
25914 +- 17% -72.2% 7206 +-101% numa-vmstat.node2.nr_zone_active_anon
11051 +-127% +301.0% 44309 +- 42% numa-vmstat.node3.nr_active_anon
36227 +- 40% -66.7% 12049 +- 93% numa-vmstat.node3.nr_free_cma
0.33 +-141% +25000.0% 83.67 +- 81% numa-vmstat.node3.nr_inactive_file
8739 +12.2% 9806 +- 8% numa-vmstat.node3.nr_kernel_stack
696.67 +-137% +3299.7% 23684 +- 71% numa-vmstat.node3.nr_shmem
3609 +- 6% +122.9% 8044 +- 42% numa-vmstat.node3.nr_slab_reclaimable
61799 +- 4% -7.8% 56960 numa-vmstat.node3.nr_unevictable
11053 +-127% +301.4% 44361 +- 42% numa-vmstat.node3.nr_zone_active_anon
0.33 +-141% +25000.0% 83.67 +- 81% numa-vmstat.node3.nr_zone_inactive_file
61799 +- 4% -7.8% 56960 numa-vmstat.node3.nr_zone_unevictable
217951 +- 8% +280.8% 829976 +- 65% numa-vmstat.node3.numa_hit
91303 +- 19% +689.3% 720647 +- 77% numa-vmstat.node3.numa_local
126648 -13.7% 109329 +- 13% numa-vmstat.node3.numa_other
8.54 -0.1 8.40 perf-profile.calltrace.cycles-pp.dequeue_task_fair.__schedule.schedule.pipe_wait.pipe_read
5.04 -0.1 4.94 perf-profile.calltrace.cycles-pp.__switch_to.read
3.43 -0.1 3.35 perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.write
2.77 -0.1 2.72 perf-profile.calltrace.cycles-pp.reweight_entity.enqueue_task_fair.ttwu_do_activate.try_to_wake_up.autoremove_wake_function
1.99 -0.0 1.94 perf-profile.calltrace.cycles-pp.copy_page_to_iter.pipe_read.__vfs_read.vfs_read.ksys_read
0.60 +- 2% -0.0 0.57 +- 2% perf-profile.calltrace.cycles-pp.find_next_bit.cpumask_next_wrap.select_idle_sibling.select_task_rq_fair.try_to_wake_up
0.81 -0.0 0.78 perf-profile.calltrace.cycles-pp.___perf_sw_event.__schedule.schedule.pipe_wait.pipe_read
0.78 +0.0 0.80 perf-profile.calltrace.cycles-pp.__fdget_pos.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe.write
0.73 +0.0 0.75 perf-profile.calltrace.cycles-pp.__fget_light.__fdget_pos.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.92 +0.0 0.95 perf-profile.calltrace.cycles-pp.check_preempt_wakeup.check_preempt_curr.ttwu_do_wakeup.try_to_wake_up.autoremove_wake_function
2.11 +0.0 2.15 perf-profile.calltrace.cycles-pp.security_file_permission.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
7.00 -0.1 6.86 perf-profile.children.cycles-pp.syscall_return_via_sysret
5.26 -0.1 5.14 perf-profile.children.cycles-pp.__switch_to
5.65 -0.1 5.56 perf-profile.children.cycles-pp.reweight_entity
2.17 -0.1 2.12 perf-profile.children.cycles-pp.copy_page_to_iter
2.94 -0.0 2.90 perf-profile.children.cycles-pp.update_cfs_group
3.11 -0.0 3.07 perf-profile.children.cycles-pp.pick_next_task_fair
2.59 -0.0 2.55 perf-profile.children.cycles-pp.load_new_mm_cr3
1.92 -0.0 1.88 perf-profile.children.cycles-pp._raw_spin_lock_irqsave
1.11 -0.0 1.08 +- 2% perf-profile.children.cycles-pp.find_next_bit
0.59 -0.0 0.56 perf-profile.children.cycles-pp.finish_task_switch
0.14 +- 15% -0.0 0.11 +- 16% perf-profile.children.cycles-pp.write@plt
1.21 -0.0 1.18 perf-profile.children.cycles-pp.set_next_entity
0.85 -0.0 0.82 perf-profile.children.cycles-pp.___perf_sw_event
0.13 +- 3% -0.0 0.11 +- 4% perf-profile.children.cycles-pp.timespec_trunc
0.47 +- 2% -0.0 0.45 perf-profile.children.cycles-pp.anon_pipe_buf_release
0.38 +- 2% -0.0 0.36 perf-profile.children.cycles-pp.file_update_time
0.74 -0.0 0.73 perf-profile.children.cycles-pp.copyout
0.41 +- 2% -0.0 0.39 perf-profile.children.cycles-pp.copy_user_enhanced_fast_string
0.32 -0.0 0.30 perf-profile.children.cycles-pp.__x64_sys_read
0.14 -0.0 0.12 +- 3% perf-profile.children.cycles-pp.current_kernel_time64
0.91 +0.0 0.92 perf-profile.children.cycles-pp.touch_atime
0.40 +0.0 0.41 perf-profile.children.cycles-pp._cond_resched
0.18 +- 2% +0.0 0.20 perf-profile.children.cycles-pp.activate_task
0.05 +0.0 0.07 +- 6% perf-profile.children.cycles-pp.default_wake_function
0.24 +0.0 0.27 +- 3% perf-profile.children.cycles-pp.rcu_all_qs
0.60 +- 2% +0.0 0.64 +- 2% perf-profile.children.cycles-pp.update_min_vruntime
0.42 +- 4% +0.0 0.46 +- 4% perf-profile.children.cycles-pp.probe_sched_switch
1.33 +0.0 1.38 perf-profile.children.cycles-pp.__fget_light
0.53 +- 2% +0.1 0.58 perf-profile.children.cycles-pp.entry_SYSCALL_64_stage2
0.31 +0.1 0.36 +- 2% perf-profile.children.cycles-pp.generic_pipe_buf_confirm
4.35 +0.1 4.41 perf-profile.children.cycles-pp.switch_mm_irqs_off
2.52 +0.1 2.58 perf-profile.children.cycles-pp.selinux_file_permission
0.00 +0.1 0.07 +- 11% perf-profile.children.cycles-pp.hrtick_update
7.00 -0.1 6.86 perf-profile.self.cycles-pp.syscall_return_via_sysret
5.26 -0.1 5.14 perf-profile.self.cycles-pp.__switch_to
0.29 -0.1 0.19 +- 2% perf-profile.self.cycles-pp.ksys_read
1.49 -0.1 1.43 perf-profile.self.cycles-pp.dequeue_task_fair
2.41 -0.1 2.35 perf-profile.self.cycles-pp.__schedule
1.46 -0.0 1.41 perf-profile.self.cycles-pp.select_task_rq_fair
2.94 -0.0 2.90 perf-profile.self.cycles-pp.update_cfs_group
0.44 -0.0 0.40 perf-profile.self.cycles-pp.dequeue_entity
0.48 -0.0 0.44 perf-profile.self.cycles-pp.finish_task_switch
2.59 -0.0 2.55 perf-profile.self.cycles-pp.load_new_mm_cr3
1.11 -0.0 1.08 +- 2% perf-profile.self.cycles-pp.find_next_bit
1.91 -0.0 1.88 perf-profile.self.cycles-pp._raw_spin_lock_irqsave
0.78 -0.0 0.75 perf-profile.self.cycles-pp.___perf_sw_event
0.14 +- 15% -0.0 0.11 +- 16% perf-profile.self.cycles-pp.write@plt
0.37 -0.0 0.35 +- 2% perf-profile.self.cycles-pp.__wake_up_common_lock
0.20 +- 2% -0.0 0.17 +- 2% perf-profile.self.cycles-pp.__fdget_pos
0.47 +- 2% -0.0 0.44 perf-profile.self.cycles-pp.anon_pipe_buf_release
0.87 -0.0 0.85 perf-profile.self.cycles-pp.copy_user_generic_unrolled
0.13 +- 3% -0.0 0.11 +- 4% perf-profile.self.cycles-pp.timespec_trunc
0.41 +- 2% -0.0 0.39 perf-profile.self.cycles-pp.copy_user_enhanced_fast_string
0.38 -0.0 0.36 perf-profile.self.cycles-pp.__wake_up_common
0.32 -0.0 0.30 perf-profile.self.cycles-pp.__x64_sys_read
0.14 +- 3% -0.0 0.12 +- 3% perf-profile.self.cycles-pp.current_kernel_time64
0.30 -0.0 0.28 perf-profile.self.cycles-pp.set_next_entity
0.28 +- 3% +0.0 0.30 perf-profile.self.cycles-pp._cond_resched
0.18 +- 2% +0.0 0.20 perf-profile.self.cycles-pp.activate_task
0.17 +- 2% +0.0 0.19 perf-profile.self.cycles-pp.__might_fault
0.05 +0.0 0.07 +- 6% perf-profile.self.cycles-pp.default_wake_function
0.17 +- 2% +0.0 0.20 perf-profile.self.cycles-pp.ttwu_do_activate
0.66 +0.0 0.69 perf-profile.self.cycles-pp.write
0.24 +0.0 0.27 +- 3% perf-profile.self.cycles-pp.rcu_all_qs
0.67 +0.0 0.70 perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
0.60 +- 2% +0.0 0.64 +- 2% perf-profile.self.cycles-pp.update_min_vruntime
0.42 +- 4% +0.0 0.46 +- 4% perf-profile.self.cycles-pp.probe_sched_switch
1.33 +0.0 1.37 perf-profile.self.cycles-pp.__fget_light
1.61 +0.0 1.66 perf-profile.self.cycles-pp.pipe_read
0.53 +- 2% +0.1 0.58 perf-profile.self.cycles-pp.entry_SYSCALL_64_stage2
0.31 +0.1 0.36 +- 2% perf-profile.self.cycles-pp.generic_pipe_buf_confirm
1.04 +0.1 1.11 perf-profile.self.cycles-pp.pipe_write
0.00 +0.1 0.07 +- 11% perf-profile.self.cycles-pp.hrtick_update
2.00 +0.1 2.08 perf-profile.self.cycles-pp.switch_mm_irqs_off
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/never/page_fault3/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
1:3 -33% :3 dmesg.WARNING:stack_going_in_the_wrong_direction?ip=file_update_time/0x
:3 33% 1:3 stderr.mount.nfs:Connection_timed_out
34:3 -401% 22:3 perf-profile.calltrace.cycles-pp.error_entry.testcase
17:3 -207% 11:3 perf-profile.calltrace.cycles-pp.sync_regs.error_entry.testcase
34:3 -404% 22:3 perf-profile.children.cycles-pp.error_entry
0:3 -2% 0:3 perf-profile.children.cycles-pp.error_exit
16:3 -196% 11:3 perf-profile.self.cycles-pp.error_entry
0:3 -2% 0:3 perf-profile.self.cycles-pp.error_exit
%stddev %change %stddev
\ | \
467454 -1.8% 459251 will-it-scale.per_process_ops
10856 +- 4% -23.1% 8344 +- 7% will-it-scale.per_thread_ops
118134 +- 2% +11.7% 131943 will-it-scale.time.involuntary_context_switches
6.277e+08 +- 4% -23.1% 4.827e+08 +- 7% will-it-scale.time.minor_page_faults
7406 +5.8% 7839 will-it-scale.time.percent_of_cpu_this_job_got
44526 +5.8% 47106 will-it-scale.time.system_time
7351468 +- 5% -18.3% 6009014 +- 7% will-it-scale.time.voluntary_context_switches
91835846 -2.2% 89778599 will-it-scale.workload
2534640 +4.3% 2643005 +- 2% interrupts.CAL:Function_call_interrupts
2819 +- 5% +22.9% 3464 +- 18% kthread_noise.total_time
30273 +- 4% -12.7% 26415 +- 5% vmstat.system.cs
1.52 +- 2% +15.2% 1.75 +- 2% irq_exception_noise.__do_page_fault.99th
296.67 +- 12% -36.7% 187.67 +- 12% irq_exception_noise.softirq_time
230900 +- 3% +30.3% 300925 +- 3% meminfo.Inactive
230184 +- 3% +30.4% 300180 +- 3% meminfo.Inactive(anon)
11.62 +- 3% -2.2 9.40 +- 5% mpstat.cpu.idle%
0.00 +- 14% -0.0 0.00 +- 4% mpstat.cpu.iowait%
7992174 -11.1% 7101976 +- 3% softirqs.RCU
4973624 +- 2% -12.9% 4333370 +- 2% softirqs.SCHED
118134 +- 2% +11.7% 131943 time.involuntary_context_switches
6.277e+08 +- 4% -23.1% 4.827e+08 +- 7% time.minor_page_faults
7406 +5.8% 7839 time.percent_of_cpu_this_job_got
44526 +5.8% 47106 time.system_time
7351468 +- 5% -18.3% 6009014 +- 7% time.voluntary_context_switches
2.702e+09 +- 5% -16.7% 2.251e+09 +- 7% cpuidle.C1E.time
6834329 +- 5% -15.8% 5756243 +- 7% cpuidle.C1E.usage
1.046e+10 +- 3% -19.8% 8.389e+09 +- 4% cpuidle.C6.time
13961845 +- 3% -19.3% 11265555 +- 4% cpuidle.C6.usage
1309307 +- 7% -14.8% 1116168 +- 8% cpuidle.POLL.time
19774 +- 6% -13.7% 17063 +- 7% cpuidle.POLL.usage
2523 +- 4% -11.1% 2243 +- 4% slabinfo.biovec-64.active_objs
2523 +- 4% -11.1% 2243 +- 4% slabinfo.biovec-64.num_objs
2610 +- 8% -33.7% 1731 +- 22% slabinfo.dmaengine-unmap-16.active_objs
2610 +- 8% -33.7% 1731 +- 22% slabinfo.dmaengine-unmap-16.num_objs
5118 +- 17% -22.6% 3962 +- 9% slabinfo.eventpoll_pwq.active_objs
5118 +- 17% -22.6% 3962 +- 9% slabinfo.eventpoll_pwq.num_objs
4583 +- 3% -14.0% 3941 +- 4% slabinfo.sock_inode_cache.active_objs
4583 +- 3% -14.0% 3941 +- 4% slabinfo.sock_inode_cache.num_objs
1933 +2.6% 1984 turbostat.Avg_MHz
6832021 +- 5% -15.8% 5754156 +- 7% turbostat.C1E
2.32 +- 5% -0.4 1.94 +- 7% turbostat.C1E%
13954211 +- 3% -19.3% 11259436 +- 4% turbostat.C6
8.97 +- 3% -1.8 7.20 +- 4% turbostat.C6%
6.18 +- 4% -17.1% 5.13 +- 5% turbostat.CPU%c1
5.12 +- 3% -21.7% 4.01 +- 4% turbostat.CPU%c6
1.76 +- 2% -34.7% 1.15 +- 2% turbostat.Pkg%pc2
57314 +- 4% +30.4% 74717 +- 4% proc-vmstat.nr_inactive_anon
57319 +- 4% +30.4% 74719 +- 4% proc-vmstat.nr_zone_inactive_anon
24415 +- 19% -62.2% 9236 +- 7% proc-vmstat.numa_hint_faults
69661453 -1.8% 68405712 proc-vmstat.numa_hit
69553390 -1.8% 68297790 proc-vmstat.numa_local
8792 +- 29% -92.6% 654.33 +- 23% proc-vmstat.numa_pages_migrated
40251 +- 32% -76.5% 9474 +- 3% proc-vmstat.numa_pte_updates
69522532 -1.6% 68383074 proc-vmstat.pgalloc_normal
2.762e+10 -2.2% 2.701e+10 proc-vmstat.pgfault
68825100 -1.5% 67772256 proc-vmstat.pgfree
8792 +- 29% -92.6% 654.33 +- 23% proc-vmstat.pgmigrate_success
57992 +- 6% +56.2% 90591 +- 3% numa-meminfo.node0.Inactive
57916 +- 6% +56.3% 90513 +- 3% numa-meminfo.node0.Inactive(anon)
37285 +- 12% +36.0% 50709 +- 5% numa-meminfo.node0.SReclaimable
110971 +- 8% +22.7% 136209 +- 8% numa-meminfo.node0.Slab
23601 +- 55% +559.5% 155651 +- 36% numa-meminfo.node1.AnonPages
62484 +- 12% +17.5% 73417 +- 3% numa-meminfo.node1.Inactive
62323 +- 12% +17.2% 73023 +- 4% numa-meminfo.node1.Inactive(anon)
109714 +- 63% -85.6% 15832 +- 96% numa-meminfo.node2.AnonPages
52236 +- 13% +22.7% 64074 +- 3% numa-meminfo.node2.Inactive
51922 +- 12% +23.2% 63963 +- 3% numa-meminfo.node2.Inactive(anon)
60241 +- 11% +21.9% 73442 +- 8% numa-meminfo.node3.Inactive
60077 +- 12% +22.0% 73279 +- 8% numa-meminfo.node3.Inactive(anon)
14093 +- 6% +55.9% 21977 +- 3% numa-vmstat.node0.nr_inactive_anon
9321 +- 12% +36.0% 12675 +- 5% numa-vmstat.node0.nr_slab_reclaimable
14090 +- 6% +56.0% 21977 +- 3% numa-vmstat.node0.nr_zone_inactive_anon
5900 +- 55% +559.4% 38909 +- 36% numa-vmstat.node1.nr_anon_pages
15413 +- 12% +14.8% 17688 +- 4% numa-vmstat.node1.nr_inactive_anon
15413 +- 12% +14.8% 17688 +- 4% numa-vmstat.node1.nr_zone_inactive_anon
27430 +- 63% -85.6% 3960 +- 96% numa-vmstat.node2.nr_anon_pages
12928 +- 12% +20.0% 15508 +- 3% numa-vmstat.node2.nr_inactive_anon
12927 +- 12% +20.0% 15507 +- 3% numa-vmstat.node2.nr_zone_inactive_anon
6229 +- 10% +117.5% 13547 +- 44% numa-vmstat.node3
14669 +- 11% +19.6% 17537 +- 7% numa-vmstat.node3.nr_inactive_anon
14674 +- 11% +19.5% 17541 +- 7% numa-vmstat.node3.nr_zone_inactive_anon
24617 +-141% -100.0% 0.00 latency_stats.avg.io_schedule.nfs_lock_and_join_requests.nfs_updatepage.nfs_write_end.generic_perform_write.nfs_file_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
5049 +-105% -99.4% 28.33 +- 82% latency_stats.avg.call_rwsem_down_write_failed.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
152457 +- 27% +233.6% 508656 +- 92% latency_stats.avg.max
0.00 +3.9e+107% 390767 +-141% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_openat
24617 +-141% -100.0% 0.00 latency_stats.max.io_schedule.nfs_lock_and_join_requests.nfs_updatepage.nfs_write_end.generic_perform_write.nfs_file_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
4240 +-141% -100.0% 0.00 latency_stats.max.call_rwsem_down_write_failed.do_unlinkat.do_syscall_64.entry_SYSCALL_64_after_hwframe
8565 +- 70% -99.1% 80.33 +-115% latency_stats.max.call_rwsem_down_write_failed.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
204835 +- 6% +457.6% 1142244 +-114% latency_stats.max.max
0.00 +5.1e+105% 5057 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_access.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_openat.do_filp_open
0.00 +1e+108% 995083 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_openat
13175 +- 4% -100.0% 0.00 latency_stats.sum.io_schedule.__lock_page_or_retry.filemap_fault.__do_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault.page_fault
24617 +-141% -100.0% 0.00 latency_stats.sum.io_schedule.nfs_lock_and_join_requests.nfs_updatepage.nfs_write_end.generic_perform_write.nfs_file_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
4260 +-141% -100.0% 0.00 latency_stats.sum.call_rwsem_down_write_failed.do_unlinkat.do_syscall_64.entry_SYSCALL_64_after_hwframe
8640 +- 70% -97.5% 216.33 +-108% latency_stats.sum.call_rwsem_down_write_failed.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
6673 +- 89% -92.8% 477.67 +- 74% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
0.00 +4.2e+105% 4228 +-130% latency_stats.sum.io_schedule.__lock_page_killable.__lock_page_or_retry.filemap_fault.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault.page_fault
0.00 +7.5e+105% 7450 +- 98% latency_stats.sum.io_schedule.__lock_page_or_retry.filemap_fault.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault.page_fault
0.00 +1.3e+106% 13050 +-141% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_access.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_openat.do_filp_open
0.00 +1.5e+110% 1.508e+08 +-141% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_openat
0.97 -0.0 0.94 perf-stat.branch-miss-rate%
1.329e+11 -2.6% 1.294e+11 perf-stat.branch-misses
2.254e+11 -1.9% 2.21e+11 perf-stat.cache-references
18308779 +- 4% -12.8% 15969618 +- 5% perf-stat.context-switches
3.20 +1.8% 3.26 perf-stat.cpi
2.233e+14 +2.7% 2.293e+14 perf-stat.cpu-cycles
4.01 -0.2 3.83 perf-stat.dTLB-store-miss-rate%
4.51e+11 -2.2% 4.41e+11 perf-stat.dTLB-store-misses
1.08e+13 +2.6% 1.109e+13 perf-stat.dTLB-stores
3.158e+10 +- 5% +16.8% 3.689e+10 +- 2% perf-stat.iTLB-load-misses
2214 +- 5% -13.8% 1907 +- 2% perf-stat.instructions-per-iTLB-miss
0.31 -1.8% 0.31 perf-stat.ipc
2.762e+10 -2.2% 2.701e+10 perf-stat.minor-faults
1.535e+10 -11.2% 1.362e+10 perf-stat.node-loads
9.75 +1.1 10.89 perf-stat.node-store-miss-rate%
3.012e+09 +10.6% 3.332e+09 +- 2% perf-stat.node-store-misses
2.787e+10 -2.2% 2.725e+10 perf-stat.node-stores
2.762e+10 -2.2% 2.701e+10 perf-stat.page-faults
759458 +3.2% 783404 perf-stat.path-length
246.39 +- 15% -20.4% 196.12 +- 6% sched_debug.cfs_rq:/.load_avg.max
0.21 +- 3% +9.0% 0.23 +- 4% sched_debug.cfs_rq:/.nr_running.stddev
16.64 +- 27% +61.0% 26.79 +- 17% sched_debug.cfs_rq:/.nr_spread_over.max
75.15 -14.4% 64.30 +- 4% sched_debug.cfs_rq:/.util_avg.stddev
178.80 +- 3% +25.4% 224.12 +- 7% sched_debug.cfs_rq:/.util_est_enqueued.avg
1075 +- 5% -12.3% 943.36 +- 2% sched_debug.cfs_rq:/.util_est_enqueued.max
2093630 +- 27% -36.1% 1337941 +- 16% sched_debug.cpu.avg_idle.max
297057 +- 11% +37.8% 409294 +- 14% sched_debug.cpu.avg_idle.min
293240 +- 55% -62.3% 110571 +- 13% sched_debug.cpu.avg_idle.stddev
770075 +- 9% -19.3% 621136 +- 12% sched_debug.cpu.max_idle_balance_cost.max
48919 +- 46% -66.9% 16190 +- 81% sched_debug.cpu.max_idle_balance_cost.stddev
21716 +- 5% -16.8% 18061 +- 7% sched_debug.cpu.nr_switches.min
21519 +- 5% -17.7% 17700 +- 7% sched_debug.cpu.sched_count.min
10586 +- 5% -18.1% 8669 +- 7% sched_debug.cpu.sched_goidle.avg
14183 +- 3% -17.6% 11693 +- 5% sched_debug.cpu.sched_goidle.max
10322 +- 5% -18.6% 8407 +- 7% sched_debug.cpu.sched_goidle.min
400.99 +- 8% -13.0% 348.75 +- 3% sched_debug.cpu.sched_goidle.stddev
5459 +- 8% +10.0% 6006 +- 3% sched_debug.cpu.ttwu_local.avg
8.47 +- 42% +345.8% 37.73 +- 77% sched_debug.rt_rq:/.rt_time.max
0.61 +- 42% +343.0% 2.72 +- 77% sched_debug.rt_rq:/.rt_time.stddev
91.98 -30.9 61.11 +- 70% perf-profile.calltrace.cycles-pp.testcase
9.05 -9.1 0.00 perf-profile.calltrace.cycles-pp.__do_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
8.91 -8.9 0.00 perf-profile.calltrace.cycles-pp.shmem_fault.__do_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
8.06 -8.1 0.00 perf-profile.calltrace.cycles-pp.shmem_getpage_gfp.shmem_fault.__do_fault.__handle_mm_fault.handle_mm_fault
7.59 -7.6 0.00 perf-profile.calltrace.cycles-pp.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault.__handle_mm_fault
7.44 -7.4 0.00 perf-profile.calltrace.cycles-pp.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
7.28 -7.3 0.00 perf-profile.calltrace.cycles-pp.alloc_set_pte.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
5.31 -5.3 0.00 perf-profile.calltrace.cycles-pp.page_add_file_rmap.alloc_set_pte.finish_fault.__handle_mm_fault.handle_mm_fault
8.08 -2.8 5.30 +- 70% perf-profile.calltrace.cycles-pp.native_irq_return_iret.testcase
5.95 -2.1 3.83 +- 70% perf-profile.calltrace.cycles-pp.find_get_entry.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault
5.95 -2.0 3.93 +- 70% perf-profile.calltrace.cycles-pp.swapgs_restore_regs_and_return_to_usermode.testcase
3.10 -1.1 2.01 +- 70% perf-profile.calltrace.cycles-pp.__perf_sw_event.__do_page_fault.do_page_fault.page_fault.testcase
2.36 -0.8 1.55 +- 70% perf-profile.calltrace.cycles-pp.___perf_sw_event.__perf_sw_event.__do_page_fault.do_page_fault.page_fault
1.08 -0.4 0.70 +- 70% perf-profile.calltrace.cycles-pp.do_page_fault.testcase
0.82 -0.3 0.54 +- 70% perf-profile.calltrace.cycles-pp.trace_graph_entry.do_page_fault.testcase
0.77 -0.3 0.50 +- 70% perf-profile.calltrace.cycles-pp.ftrace_graph_caller.__do_page_fault.do_page_fault.page_fault.testcase
0.59 -0.2 0.37 +- 70% perf-profile.calltrace.cycles-pp.down_read_trylock.__do_page_fault.do_page_fault.page_fault.testcase
91.98 -30.9 61.11 +- 70% perf-profile.children.cycles-pp.testcase
9.14 -3.2 5.99 +- 70% perf-profile.children.cycles-pp.__do_fault
8.20 -2.8 5.40 +- 70% perf-profile.children.cycles-pp.shmem_getpage_gfp
8.08 -2.8 5.31 +- 70% perf-profile.children.cycles-pp.native_irq_return_iret
6.08 -2.2 3.92 +- 70% perf-profile.children.cycles-pp.find_get_entry
6.08 -2.1 3.96 +- 70% perf-profile.children.cycles-pp.sync_regs
5.95 -2.0 3.93 +- 70% perf-profile.children.cycles-pp.swapgs_restore_regs_and_return_to_usermode
4.12 -1.4 2.73 +- 70% perf-profile.children.cycles-pp.ftrace_graph_caller
3.65 -1.2 2.42 +- 70% perf-profile.children.cycles-pp.prepare_ftrace_return
3.18 -1.1 2.07 +- 70% perf-profile.children.cycles-pp.__perf_sw_event
2.34 -0.8 1.52 +- 70% perf-profile.children.cycles-pp.fault_dirty_shared_page
0.80 -0.3 0.50 +- 70% perf-profile.children.cycles-pp._raw_spin_lock
0.76 -0.3 0.50 +- 70% perf-profile.children.cycles-pp.tlb_flush_mmu_free
0.61 -0.2 0.39 +- 70% perf-profile.children.cycles-pp.down_read_trylock
0.48 +- 2% -0.2 0.28 +- 70% perf-profile.children.cycles-pp.pmd_devmap_trans_unstable
0.26 +- 6% -0.1 0.15 +- 71% perf-profile.children.cycles-pp.ktime_get
0.20 +- 2% -0.1 0.12 +- 70% perf-profile.children.cycles-pp.perf_exclude_event
0.22 +- 2% -0.1 0.13 +- 70% perf-profile.children.cycles-pp._cond_resched
0.17 -0.1 0.11 +- 70% perf-profile.children.cycles-pp.page_rmapping
0.13 -0.1 0.07 +- 70% perf-profile.children.cycles-pp.rcu_all_qs
0.07 -0.0 0.04 +- 70% perf-profile.children.cycles-pp.ftrace_lookup_ip
22.36 -7.8 14.59 +- 70% perf-profile.self.cycles-pp.testcase
8.08 -2.8 5.31 +- 70% perf-profile.self.cycles-pp.native_irq_return_iret
6.08 -2.1 3.96 +- 70% perf-profile.self.cycles-pp.sync_regs
5.81 -2.0 3.84 +- 70% perf-profile.self.cycles-pp.swapgs_restore_regs_and_return_to_usermode
3.27 -1.6 1.65 +- 70% perf-profile.self.cycles-pp.__handle_mm_fault
3.79 -1.4 2.36 +- 70% perf-profile.self.cycles-pp.find_get_entry
3.80 -1.3 2.53 +- 70% perf-profile.self.cycles-pp.trace_graph_entry
1.10 -0.5 0.57 +- 70% perf-profile.self.cycles-pp.alloc_set_pte
1.24 -0.4 0.81 +- 70% perf-profile.self.cycles-pp.shmem_fault
0.80 -0.3 0.50 +- 70% perf-profile.self.cycles-pp._raw_spin_lock
0.81 -0.3 0.51 +- 70% perf-profile.self.cycles-pp.find_lock_entry
0.80 +- 2% -0.3 0.51 +- 70% perf-profile.self.cycles-pp.__perf_sw_event
0.61 -0.2 0.38 +- 70% perf-profile.self.cycles-pp.down_read_trylock
0.60 -0.2 0.39 +- 70% perf-profile.self.cycles-pp.shmem_getpage_gfp
0.48 -0.2 0.27 +- 70% perf-profile.self.cycles-pp.pmd_devmap_trans_unstable
0.47 -0.2 0.30 +- 70% perf-profile.self.cycles-pp.file_update_time
0.34 -0.1 0.22 +- 70% perf-profile.self.cycles-pp.do_page_fault
0.22 +- 4% -0.1 0.11 +- 70% perf-profile.self.cycles-pp.__do_fault
0.25 +- 5% -0.1 0.14 +- 71% perf-profile.self.cycles-pp.ktime_get
0.21 +- 2% -0.1 0.12 +- 70% perf-profile.self.cycles-pp.finish_fault
0.23 +- 2% -0.1 0.14 +- 70% perf-profile.self.cycles-pp.fault_dirty_shared_page
0.22 +- 2% -0.1 0.14 +- 70% perf-profile.self.cycles-pp.prepare_exit_to_usermode
0.20 +- 2% -0.1 0.12 +- 70% perf-profile.self.cycles-pp.perf_exclude_event
0.16 -0.1 0.10 +- 70% perf-profile.self.cycles-pp._cond_resched
0.13 -0.1 0.07 +- 70% perf-profile.self.cycles-pp.rcu_all_qs
0.07 -0.0 0.04 +- 70% perf-profile.self.cycles-pp.ftrace_lookup_ip
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/always/context_switch1/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
:3 33% 1:3 dmesg.WARNING:at#for_ip_interrupt_entry/0x
:3 33% 1:3 dmesg.WARNING:at#for_ip_ret_from_intr/0x
:3 67% 2:3 kmsg.pstore:crypto_comp_decompress_failed,ret=
:3 67% 2:3 kmsg.pstore:decompression_failed
%stddev %change %stddev
\ | \
223910 -1.3% 220930 will-it-scale.per_process_ops
233722 -1.0% 231288 will-it-scale.per_thread_ops
6.001e+08 +- 13% +31.4% 7.887e+08 +- 4% will-it-scale.time.involuntary_context_switches
18003 +- 4% +10.9% 19956 will-it-scale.time.minor_page_faults
1.29e+10 -2.5% 1.258e+10 will-it-scale.time.voluntary_context_switches
87865617 -1.2% 86826277 will-it-scale.workload
2880329 +- 2% +5.4% 3034904 interrupts.CAL:Function_call_interrupts
7695018 -23.3% 5905066 +- 8% meminfo.DirectMap2M
0.00 +- 39% -0.0 0.00 +- 78% mpstat.cpu.iowait%
4621 +- 12% +13.4% 5241 proc-vmstat.numa_hint_faults_local
715714 +27.6% 913142 +- 13% softirqs.SCHED
515653 +- 6% -20.0% 412650 +- 15% turbostat.C1
43643516 -1.2% 43127031 vmstat.system.cs
2893393 +- 4% -23.6% 2210524 +- 10% cpuidle.C1.time
518051 +- 6% -19.9% 415081 +- 15% cpuidle.C1.usage
23.10 +22.9% 28.38 +- 9% boot-time.boot
18.38 +23.2% 22.64 +- 12% boot-time.dhcp
5216 +5.0% 5478 +- 2% boot-time.idle
963.76 +- 44% +109.7% 2021 +- 34% irq_exception_noise.__do_page_fault.sum
6.33 +- 14% +726.3% 52.33 +- 62% irq_exception_noise.irq_time
56524 +- 7% -18.8% 45915 +- 4% irq_exception_noise.softirq_time
6.001e+08 +- 13% +31.4% 7.887e+08 +- 4% time.involuntary_context_switches
18003 +- 4% +10.9% 19956 time.minor_page_faults
1.29e+10 -2.5% 1.258e+10 time.voluntary_context_switches
1386 +- 7% +15.4% 1600 +- 11% slabinfo.scsi_sense_cache.active_objs
1386 +- 7% +15.4% 1600 +- 11% slabinfo.scsi_sense_cache.num_objs
1427 +- 5% -8.9% 1299 +- 2% slabinfo.task_group.active_objs
1427 +- 5% -8.9% 1299 +- 2% slabinfo.task_group.num_objs
65519 +- 12% +20.6% 79014 +- 16% numa-meminfo.node0.SUnreclaim
8484 -11.9% 7475 +- 7% numa-meminfo.node1.KernelStack
9264 +- 26% -33.7% 6146 +- 7% numa-meminfo.node1.Mapped
2138 +- 61% +373.5% 10127 +- 92% numa-meminfo.node3.Inactive
2059 +- 61% +387.8% 10046 +- 93% numa-meminfo.node3.Inactive(anon)
16379 +- 12% +20.6% 19752 +- 16% numa-vmstat.node0.nr_slab_unreclaimable
8483 -11.9% 7474 +- 7% numa-vmstat.node1.nr_kernel_stack
6250 +- 29% -42.8% 3575 +- 24% numa-vmstat.node2
3798 +- 17% +63.7% 6218 +- 5% numa-vmstat.node3
543.00 +- 61% +368.1% 2541 +- 91% numa-vmstat.node3.nr_inactive_anon
543.33 +- 61% +367.8% 2541 +- 91% numa-vmstat.node3.nr_zone_inactive_anon
4.138e+13 -1.1% 4.09e+13 perf-stat.branch-instructions
6.569e+11 -2.0% 6.441e+11 perf-stat.branch-misses
2.645e+10 -1.2% 2.613e+10 perf-stat.context-switches
1.21 +1.2% 1.23 perf-stat.cpi
153343 +- 2% -12.1% 134776 perf-stat.cpu-migrations
5.966e+13 -1.3% 5.889e+13 perf-stat.dTLB-loads
3.736e+13 -1.2% 3.69e+13 perf-stat.dTLB-stores
5.85 +- 15% +8.8 14.67 +- 9% perf-stat.iTLB-load-miss-rate%
3.736e+09 +- 17% +161.3% 9.76e+09 +- 11% perf-stat.iTLB-load-misses
5.987e+10 -5.4% 5.667e+10 perf-stat.iTLB-loads
2.079e+14 -1.2% 2.054e+14 perf-stat.instructions
57547 +- 18% -62.9% 21340 +- 11% perf-stat.instructions-per-iTLB-miss
0.82 -1.2% 0.81 perf-stat.ipc
27502531 +- 8% +9.5% 30122136 +- 3% perf-stat.node-store-misses
1449 +- 27% -34.6% 948.85 sched_debug.cfs_rq:/.load.min
319416 +-115% -188.5% -282549 sched_debug.cfs_rq:/.spread0.avg
657044 +- 55% -88.3% 76887 +- 23% sched_debug.cfs_rq:/.spread0.max
-1525243 +54.6% -2357898 sched_debug.cfs_rq:/.spread0.min
101614 +- 6% +30.6% 132713 +- 19% sched_debug.cpu.avg_idle.stddev
11.54 +- 41% -61.2% 4.48 sched_debug.cpu.cpu_load[1].avg
1369 +- 67% -98.5% 20.67 +- 48% sched_debug.cpu.cpu_load[1].max
99.29 +- 67% -97.6% 2.35 +- 26% sched_debug.cpu.cpu_load[1].stddev
9.58 +- 38% -55.2% 4.29 sched_debug.cpu.cpu_load[2].avg
1024 +- 68% -98.5% 15.27 +- 36% sched_debug.cpu.cpu_load[2].max
74.51 +- 67% -97.3% 1.99 +- 15% sched_debug.cpu.cpu_load[2].stddev
7.37 +- 29% -42.0% 4.28 sched_debug.cpu.cpu_load[3].avg
600.58 +- 68% -97.9% 12.48 +- 20% sched_debug.cpu.cpu_load[3].max
43.98 +- 66% -95.8% 1.83 +- 5% sched_debug.cpu.cpu_load[3].stddev
5.95 +- 19% -28.1% 4.28 sched_debug.cpu.cpu_load[4].avg
325.39 +- 67% -96.4% 11.67 +- 10% sched_debug.cpu.cpu_load[4].max
24.19 +- 65% -92.5% 1.81 +- 3% sched_debug.cpu.cpu_load[4].stddev
907.23 +- 4% -14.1% 779.70 +- 10% sched_debug.cpu.nr_load_updates.stddev
0.00 +- 83% +122.5% 0.00 sched_debug.rt_rq:/.rt_time.min
8.49 +- 2% -0.3 8.21 +- 2% perf-profile.calltrace.cycles-pp.dequeue_task_fair.__schedule.schedule.pipe_wait.pipe_read
57.28 -0.3 57.01 perf-profile.calltrace.cycles-pp.read
5.06 -0.2 4.85 perf-profile.calltrace.cycles-pp.select_task_rq_fair.try_to_wake_up.autoremove_wake_function.__wake_up_common.__wake_up_common_lock
4.98 -0.2 4.78 perf-profile.calltrace.cycles-pp.__switch_to.read
3.55 -0.2 3.39 +- 2% perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.read
2.72 -0.1 2.60 perf-profile.calltrace.cycles-pp.reweight_entity.enqueue_task_fair.ttwu_do_activate.try_to_wake_up.autoremove_wake_function
2.67 -0.1 2.57 +- 2% perf-profile.calltrace.cycles-pp.reweight_entity.dequeue_task_fair.__schedule.schedule.pipe_wait
3.40 -0.1 3.31 perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.write
3.77 -0.1 3.68 perf-profile.calltrace.cycles-pp.select_idle_sibling.select_task_rq_fair.try_to_wake_up.autoremove_wake_function.__wake_up_common
1.95 -0.1 1.88 perf-profile.calltrace.cycles-pp.copy_page_to_iter.pipe_read.__vfs_read.vfs_read.ksys_read
2.19 -0.1 2.13 perf-profile.calltrace.cycles-pp.__switch_to_asm.read
1.30 -0.1 1.25 perf-profile.calltrace.cycles-pp.update_curr.reweight_entity.enqueue_task_fair.ttwu_do_activate.try_to_wake_up
1.27 -0.1 1.22 +- 2% perf-profile.calltrace.cycles-pp.update_curr.reweight_entity.dequeue_task_fair.__schedule.schedule
2.29 -0.0 2.24 perf-profile.calltrace.cycles-pp.load_new_mm_cr3.switch_mm_irqs_off.__schedule.schedule.pipe_wait
0.96 -0.0 0.92 perf-profile.calltrace.cycles-pp.__calc_delta.update_curr.reweight_entity.dequeue_task_fair.__schedule
0.85 -0.0 0.81 +- 3% perf-profile.calltrace.cycles-pp.cpumask_next_wrap.select_idle_sibling.select_task_rq_fair.try_to_wake_up.autoremove_wake_function
1.63 -0.0 1.59 perf-profile.calltrace.cycles-pp.native_write_msr.read
0.72 -0.0 0.69 perf-profile.calltrace.cycles-pp.copyout.copy_page_to_iter.pipe_read.__vfs_read.vfs_read
0.65 +- 2% -0.0 0.62 perf-profile.calltrace.cycles-pp._raw_spin_lock_irqsave.try_to_wake_up.autoremove_wake_function.__wake_up_common.__wake_up_common_lock
0.61 -0.0 0.58 +- 2% perf-profile.calltrace.cycles-pp.find_next_bit.cpumask_next_wrap.select_idle_sibling.select_task_rq_fair.try_to_wake_up
0.88 -0.0 0.85 perf-profile.calltrace.cycles-pp.touch_atime.pipe_read.__vfs_read.vfs_read.ksys_read
0.80 -0.0 0.77 +- 2% perf-profile.calltrace.cycles-pp.___perf_sw_event.__schedule.schedule.pipe_wait.pipe_read
0.82 -0.0 0.79 perf-profile.calltrace.cycles-pp.prepare_to_wait.pipe_wait.pipe_read.__vfs_read.vfs_read
0.72 -0.0 0.70 perf-profile.calltrace.cycles-pp.mutex_lock.pipe_write.__vfs_write.vfs_write.ksys_write
0.56 +- 2% -0.0 0.53 perf-profile.calltrace.cycles-pp.update_rq_clock.try_to_wake_up.autoremove_wake_function.__wake_up_common.__wake_up_common_lock
0.83 -0.0 0.81 perf-profile.calltrace.cycles-pp.__wake_up_common_lock.pipe_read.__vfs_read.vfs_read.ksys_read
42.40 +0.3 42.69 perf-profile.calltrace.cycles-pp.write
31.80 +0.4 32.18 perf-profile.calltrace.cycles-pp.__vfs_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
24.35 +0.5 24.84 perf-profile.calltrace.cycles-pp.pipe_wait.pipe_read.__vfs_read.vfs_read.ksys_read
20.36 +0.6 20.92 +- 2% perf-profile.calltrace.cycles-pp.try_to_wake_up.autoremove_wake_function.__wake_up_common.__wake_up_common_lock.pipe_write
22.01 +0.6 22.58 perf-profile.calltrace.cycles-pp.schedule.pipe_wait.pipe_read.__vfs_read.vfs_read
21.87 +0.6 22.46 perf-profile.calltrace.cycles-pp.__schedule.schedule.pipe_wait.pipe_read.__vfs_read
3.15 +- 11% +1.0 4.12 +- 14% perf-profile.calltrace.cycles-pp.ttwu_do_wakeup.try_to_wake_up.autoremove_wake_function.__wake_up_common.__wake_up_common_lock
1.07 +- 34% +1.1 2.12 +- 31% perf-profile.calltrace.cycles-pp.tracing_record_taskinfo_sched_switch.__schedule.schedule.pipe_wait.pipe_read
0.66 +- 75% +1.1 1.72 +- 37% perf-profile.calltrace.cycles-pp.trace_save_cmdline.tracing_record_taskinfo.ttwu_do_wakeup.try_to_wake_up.autoremove_wake_function
0.75 +- 74% +1.1 1.88 +- 34% perf-profile.calltrace.cycles-pp.tracing_record_taskinfo.ttwu_do_wakeup.try_to_wake_up.autoremove_wake_function.__wake_up_common
0.69 +- 76% +1.2 1.85 +- 36% perf-profile.calltrace.cycles-pp.trace_save_cmdline.tracing_record_taskinfo_sched_switch.__schedule.schedule.pipe_wait
8.73 +- 2% -0.3 8.45 perf-profile.children.cycles-pp.dequeue_task_fair
57.28 -0.3 57.01 perf-profile.children.cycles-pp.read
6.95 -0.2 6.70 perf-profile.children.cycles-pp.syscall_return_via_sysret
5.57 -0.2 5.35 perf-profile.children.cycles-pp.reweight_entity
5.26 -0.2 5.05 perf-profile.children.cycles-pp.select_task_rq_fair
5.19 -0.2 4.99 perf-profile.children.cycles-pp.__switch_to
4.90 -0.2 4.73 +- 2% perf-profile.children.cycles-pp.update_curr
1.27 -0.1 1.13 +- 8% perf-profile.children.cycles-pp.fsnotify
3.92 -0.1 3.83 perf-profile.children.cycles-pp.select_idle_sibling
2.01 -0.1 1.93 perf-profile.children.cycles-pp.__calc_delta
2.14 -0.1 2.06 perf-profile.children.cycles-pp.copy_page_to_iter
1.58 -0.1 1.51 perf-profile.children.cycles-pp._raw_spin_unlock_irqrestore
2.90 -0.1 2.84 perf-profile.children.cycles-pp.update_cfs_group
1.93 -0.1 1.87 perf-profile.children.cycles-pp._raw_spin_lock_irqsave
2.35 -0.1 2.29 perf-profile.children.cycles-pp.__switch_to_asm
1.33 -0.1 1.27 +- 3% perf-profile.children.cycles-pp.cpumask_next_wrap
2.57 -0.1 2.52 perf-profile.children.cycles-pp.load_new_mm_cr3
1.53 -0.1 1.47 +- 2% perf-profile.children.cycles-pp.__fdget_pos
1.11 -0.0 1.07 +- 2% perf-profile.children.cycles-pp.find_next_bit
1.18 -0.0 1.14 perf-profile.children.cycles-pp.update_rq_clock
0.88 -0.0 0.83 perf-profile.children.cycles-pp.copy_user_generic_unrolled
1.70 -0.0 1.65 perf-profile.children.cycles-pp.native_write_msr
0.97 -0.0 0.93 +- 2% perf-profile.children.cycles-pp.account_entity_dequeue
0.59 -0.0 0.56 perf-profile.children.cycles-pp.finish_task_switch
0.91 -0.0 0.88 perf-profile.children.cycles-pp.touch_atime
0.69 -0.0 0.65 perf-profile.children.cycles-pp.account_entity_enqueue
2.13 -0.0 2.09 perf-profile.children.cycles-pp.mutex_lock
0.32 +- 3% -0.0 0.29 +- 4% perf-profile.children.cycles-pp.__sb_start_write
0.84 -0.0 0.81 +- 2% perf-profile.children.cycles-pp.___perf_sw_event
0.89 -0.0 0.87 perf-profile.children.cycles-pp.prepare_to_wait
0.73 -0.0 0.71 perf-profile.children.cycles-pp.copyout
0.31 +- 2% -0.0 0.28 +- 3% perf-profile.children.cycles-pp.__list_del_entry_valid
0.46 +- 2% -0.0 0.44 perf-profile.children.cycles-pp.anon_pipe_buf_release
0.38 -0.0 0.36 +- 3% perf-profile.children.cycles-pp.idle_cpu
0.32 -0.0 0.30 +- 2% perf-profile.children.cycles-pp.__x64_sys_read
0.21 +- 2% -0.0 0.20 +- 2% perf-profile.children.cycles-pp.deactivate_task
0.13 -0.0 0.12 +- 4% perf-profile.children.cycles-pp.timespec_trunc
0.09 -0.0 0.08 perf-profile.children.cycles-pp.iov_iter_init
0.08 -0.0 0.07 perf-profile.children.cycles-pp.native_load_tls
0.11 +- 4% +0.0 0.12 perf-profile.children.cycles-pp.tick_sched_timer
0.08 +- 5% +0.0 0.10 +- 4% perf-profile.children.cycles-pp.finish_wait
0.38 +- 2% +0.0 0.40 +- 2% perf-profile.children.cycles-pp.file_update_time
0.31 +0.0 0.33 +- 2% perf-profile.children.cycles-pp.smp_apic_timer_interrupt
0.24 +- 3% +0.0 0.26 +- 3% perf-profile.children.cycles-pp.rcu_all_qs
0.39 +0.0 0.41 perf-profile.children.cycles-pp._cond_resched
0.05 +0.0 0.07 +- 6% perf-profile.children.cycles-pp.default_wake_function
0.23 +- 2% +0.0 0.26 +- 3% perf-profile.children.cycles-pp.current_time
0.30 +0.0 0.35 +- 2% perf-profile.children.cycles-pp.generic_pipe_buf_confirm
0.52 +0.1 0.58 perf-profile.children.cycles-pp.entry_SYSCALL_64_stage2
0.00 +0.1 0.08 +- 5% perf-profile.children.cycles-pp.hrtick_update
42.40 +0.3 42.69 perf-profile.children.cycles-pp.write
31.86 +0.4 32.26 perf-profile.children.cycles-pp.__vfs_read
24.40 +0.5 24.89 perf-profile.children.cycles-pp.pipe_wait
20.40 +0.6 20.96 +- 2% perf-profile.children.cycles-pp.try_to_wake_up
22.30 +0.6 22.89 perf-profile.children.cycles-pp.schedule
22.22 +0.6 22.84 perf-profile.children.cycles-pp.__schedule
0.99 +- 36% +0.9 1.94 +- 32% perf-profile.children.cycles-pp.tracing_record_taskinfo
3.30 +- 10% +1.0 4.27 +- 13% perf-profile.children.cycles-pp.ttwu_do_wakeup
1.14 +- 31% +1.1 2.24 +- 29% perf-profile.children.cycles-pp.tracing_record_taskinfo_sched_switch
1.59 +- 46% +2.0 3.60 +- 36% perf-profile.children.cycles-pp.trace_save_cmdline
6.95 -0.2 6.70 perf-profile.self.cycles-pp.syscall_return_via_sysret
5.19 -0.2 4.99 perf-profile.self.cycles-pp.__switch_to
1.27 -0.1 1.12 +- 8% perf-profile.self.cycles-pp.fsnotify
1.49 -0.1 1.36 perf-profile.self.cycles-pp.select_task_rq_fair
2.47 -0.1 2.37 +- 2% perf-profile.self.cycles-pp.reweight_entity
0.29 -0.1 0.19 +- 2% perf-profile.self.cycles-pp.ksys_read
1.50 -0.1 1.42 perf-profile.self.cycles-pp._raw_spin_unlock_irqrestore
2.01 -0.1 1.93 perf-profile.self.cycles-pp.__calc_delta
1.93 -0.1 1.86 perf-profile.self.cycles-pp._raw_spin_lock_irqsave
1.47 -0.1 1.40 perf-profile.self.cycles-pp.dequeue_task_fair
2.90 -0.1 2.84 perf-profile.self.cycles-pp.update_cfs_group
1.29 -0.1 1.23 perf-profile.self.cycles-pp.do_syscall_64
2.57 -0.1 2.52 perf-profile.self.cycles-pp.load_new_mm_cr3
2.28 -0.1 2.23 perf-profile.self.cycles-pp.__switch_to_asm
1.80 -0.1 1.75 perf-profile.self.cycles-pp.select_idle_sibling
1.11 -0.0 1.07 +- 2% perf-profile.self.cycles-pp.find_next_bit
0.87 -0.0 0.83 perf-profile.self.cycles-pp.copy_user_generic_unrolled
0.43 -0.0 0.39 +- 2% perf-profile.self.cycles-pp.dequeue_entity
1.70 -0.0 1.65 perf-profile.self.cycles-pp.native_write_msr
0.92 -0.0 0.88 +- 2% perf-profile.self.cycles-pp.account_entity_dequeue
0.48 -0.0 0.44 perf-profile.self.cycles-pp.finish_task_switch
0.77 -0.0 0.74 perf-profile.self.cycles-pp.___perf_sw_event
0.66 -0.0 0.63 perf-profile.self.cycles-pp.account_entity_enqueue
0.46 +- 2% -0.0 0.43 +- 2% perf-profile.self.cycles-pp.anon_pipe_buf_release
0.32 +- 3% -0.0 0.29 +- 4% perf-profile.self.cycles-pp.__sb_start_write
0.31 +- 2% -0.0 0.28 +- 3% perf-profile.self.cycles-pp.__list_del_entry_valid
0.38 -0.0 0.36 +- 3% perf-profile.self.cycles-pp.idle_cpu
0.19 +- 4% -0.0 0.17 +- 2% perf-profile.self.cycles-pp.__fdget_pos
0.50 -0.0 0.48 perf-profile.self.cycles-pp.__atime_needs_update
0.23 +- 2% -0.0 0.21 +- 3% perf-profile.self.cycles-pp.touch_atime
0.31 -0.0 0.30 perf-profile.self.cycles-pp.__x64_sys_read
0.21 +- 2% -0.0 0.20 +- 2% perf-profile.self.cycles-pp.deactivate_task
0.21 +- 2% -0.0 0.19 perf-profile.self.cycles-pp.check_preempt_curr
0.40 -0.0 0.39 perf-profile.self.cycles-pp.autoremove_wake_function
0.40 -0.0 0.38 perf-profile.self.cycles-pp.copy_user_enhanced_fast_string
0.27 -0.0 0.26 perf-profile.self.cycles-pp.pipe_wait
0.13 -0.0 0.12 +- 4% perf-profile.self.cycles-pp.timespec_trunc
0.22 +- 2% -0.0 0.20 +- 2% perf-profile.self.cycles-pp.put_prev_entity
0.09 -0.0 0.08 perf-profile.self.cycles-pp.iov_iter_init
0.08 -0.0 0.07 perf-profile.self.cycles-pp.native_load_tls
0.11 -0.0 0.10 perf-profile.self.cycles-pp.schedule
0.12 +- 4% +0.0 0.13 perf-profile.self.cycles-pp.copyin
0.08 +- 5% +0.0 0.10 +- 4% perf-profile.self.cycles-pp.finish_wait
0.18 +0.0 0.20 +- 2% perf-profile.self.cycles-pp.ttwu_do_activate
0.28 +- 2% +0.0 0.30 +- 2% perf-profile.self.cycles-pp._cond_resched
0.24 +- 3% +0.0 0.26 +- 3% perf-profile.self.cycles-pp.rcu_all_qs
0.05 +0.0 0.07 +- 6% perf-profile.self.cycles-pp.default_wake_function
0.08 +- 14% +0.0 0.11 +- 14% perf-profile.self.cycles-pp.tracing_record_taskinfo_sched_switch
0.51 +0.0 0.55 +- 4% perf-profile.self.cycles-pp.vfs_write
0.30 +0.0 0.35 +- 2% perf-profile.self.cycles-pp.generic_pipe_buf_confirm
0.52 +0.1 0.58 perf-profile.self.cycles-pp.entry_SYSCALL_64_stage2
0.00 +0.1 0.08 +- 5% perf-profile.self.cycles-pp.hrtick_update
1.97 +0.1 2.07 +- 2% perf-profile.self.cycles-pp.switch_mm_irqs_off
1.59 +- 46% +2.0 3.60 +- 36% perf-profile.self.cycles-pp.trace_save_cmdline
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/never/brk1/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
:3 33% 1:3 kmsg.pstore:crypto_comp_decompress_failed,ret=
:3 33% 1:3 kmsg.pstore:decompression_failed
%stddev %change %stddev
\ | \
997317 -2.0% 977778 will-it-scale.per_process_ops
957.00 -7.9% 881.00 +- 3% will-it-scale.per_thread_ops
18.42 +- 3% -8.2% 16.90 will-it-scale.time.user_time
1.917e+08 -2.0% 1.879e+08 will-it-scale.workload
18.42 +- 3% -8.2% 16.90 time.user_time
0.30 +- 11% -36.7% 0.19 +- 11% turbostat.Pkg%pc2
57539 +- 51% +140.6% 138439 +- 31% meminfo.CmaFree
410877 +- 11% -22.1% 320082 +- 22% meminfo.DirectMap4k
343575 +- 27% +71.3% 588703 +- 31% numa-numastat.node0.local_node
374176 +- 24% +63.3% 611007 +- 27% numa-numastat.node0.numa_hit
1056347 +- 4% -39.9% 634843 +- 38% numa-numastat.node3.local_node
1060682 +- 4% -39.0% 646862 +- 35% numa-numastat.node3.numa_hit
14383 +- 51% +140.6% 34608 +- 31% proc-vmstat.nr_free_cma
179.00 +2.4% 183.33 proc-vmstat.nr_inactive_file
179.00 +2.4% 183.33 proc-vmstat.nr_zone_inactive_file
564483 +- 3% -38.0% 350064 +- 36% proc-vmstat.pgalloc_movable
1811959 +10.8% 2008488 +- 5% proc-vmstat.pgalloc_normal
7153 +- 42% -94.0% 431.33 +-119% latency_stats.max.pipe_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
6627 +-141% +380.5% 31843 +-110% latency_stats.max.call_rwsem_down_write_failed_killable.do_mprotect_pkey.__x64_sys_mprotect.do_syscall_64.entry_SYSCALL_64_after_hwframe
15244 +- 31% -99.9% 15.00 +-141% latency_stats.sum.call_rwsem_down_read_failed.__do_page_fault.do_page_fault.page_fault.__get_user_8.exit_robust_list.mm_release.do_exit.do_group_exit.get_signal.do_signal.exit_to_usermode_loop
4301 +-117% -83.7% 700.33 +- 6% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
12153 +- 28% -83.1% 2056 +- 70% latency_stats.sum.pipe_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
6772 +-141% +1105.8% 81665 +-127% latency_stats.sum.call_rwsem_down_write_failed_killable.do_mprotect_pkey.__x64_sys_mprotect.do_syscall_64.entry_SYSCALL_64_after_hwframe
2.465e+13 -1.3% 2.434e+13 perf-stat.branch-instructions
2.691e+11 -2.1% 2.635e+11 perf-stat.branch-misses
3.402e+13 -1.4% 3.355e+13 perf-stat.dTLB-loads
1.694e+13 +1.4% 1.718e+13 perf-stat.dTLB-stores
1.75 +- 50% +4.7 6.45 +- 11% perf-stat.iTLB-load-miss-rate%
4.077e+08 +- 48% +232.3% 1.355e+09 +- 11% perf-stat.iTLB-load-misses
2.31e+10 +- 2% -14.9% 1.965e+10 +- 3% perf-stat.iTLB-loads
1.163e+14 -1.6% 1.144e+14 perf-stat.instructions
346171 +- 36% -75.3% 85575 +- 11% perf-stat.instructions-per-iTLB-miss
6.174e+08 +- 2% -9.5% 5.589e+08 perf-stat.node-store-misses
595.00 +- 10% +31.4% 782.00 +- 3% slabinfo.Acpi-State.active_objs
595.00 +- 10% +31.4% 782.00 +- 3% slabinfo.Acpi-State.num_objs
2831 +- 3% -14.0% 2434 +- 5% slabinfo.avtab_node.active_objs
2831 +- 3% -14.0% 2434 +- 5% slabinfo.avtab_node.num_objs
934.00 -10.9% 832.33 +- 5% slabinfo.inotify_inode_mark.active_objs
934.00 -10.9% 832.33 +- 5% slabinfo.inotify_inode_mark.num_objs
1232 +- 4% +13.4% 1397 +- 6% slabinfo.nsproxy.active_objs
1232 +- 4% +13.4% 1397 +- 6% slabinfo.nsproxy.num_objs
499.67 +- 12% +24.8% 623.67 +- 10% slabinfo.secpath_cache.active_objs
499.67 +- 12% +24.8% 623.67 +- 10% slabinfo.secpath_cache.num_objs
31393 +- 84% +220.1% 100477 +- 21% numa-meminfo.node0.Active
31393 +- 84% +220.1% 100477 +- 21% numa-meminfo.node0.Active(anon)
30013 +- 85% +232.1% 99661 +- 21% numa-meminfo.node0.AnonPages
21603 +- 34% -85.0% 3237 +-100% numa-meminfo.node0.Inactive
21528 +- 34% -85.0% 3237 +-100% numa-meminfo.node0.Inactive(anon)
10247 +- 35% -46.4% 5495 numa-meminfo.node0.Mapped
35388 +- 14% -41.6% 20670 +- 15% numa-meminfo.node0.SReclaimable
22911 +- 29% -82.3% 4057 +- 84% numa-meminfo.node0.Shmem
117387 +- 9% -22.5% 90986 +- 12% numa-meminfo.node0.Slab
68863 +- 67% +77.7% 122351 +- 13% numa-meminfo.node1.Active
68863 +- 67% +77.7% 122351 +- 13% numa-meminfo.node1.Active(anon)
228376 +22.3% 279406 +- 17% numa-meminfo.node1.FilePages
1481 +-116% +1062.1% 17218 +- 39% numa-meminfo.node1.Inactive
1481 +-116% +1062.0% 17216 +- 39% numa-meminfo.node1.Inactive(anon)
6593 +- 2% +11.7% 7367 +- 3% numa-meminfo.node1.KernelStack
596227 +- 8% +18.0% 703748 +- 4% numa-meminfo.node1.MemUsed
15298 +- 12% +88.5% 28843 +- 36% numa-meminfo.node1.SReclaimable
52718 +- 9% +21.0% 63810 +- 11% numa-meminfo.node1.SUnreclaim
1808 +- 97% +2723.8% 51054 +- 97% numa-meminfo.node1.Shmem
68017 +- 5% +36.2% 92654 +- 18% numa-meminfo.node1.Slab
125541 +- 29% -64.9% 44024 +- 98% numa-meminfo.node3.Active
125137 +- 29% -65.0% 43823 +- 98% numa-meminfo.node3.Active(anon)
93173 +- 25% -87.8% 11381 +- 20% numa-meminfo.node3.AnonPages
9150 +- 5% -9.3% 8301 +- 8% numa-meminfo.node3.KernelStack
7848 +- 84% +220.0% 25118 +- 21% numa-vmstat.node0.nr_active_anon
7503 +- 85% +232.1% 24914 +- 21% numa-vmstat.node0.nr_anon_pages
5381 +- 34% -85.0% 809.00 +-100% numa-vmstat.node0.nr_inactive_anon
2559 +- 35% -46.4% 1372 numa-vmstat.node0.nr_mapped
5727 +- 29% -82.3% 1014 +- 84% numa-vmstat.node0.nr_shmem
8846 +- 14% -41.6% 5167 +- 15% numa-vmstat.node0.nr_slab_reclaimable
7848 +- 84% +220.0% 25118 +- 21% numa-vmstat.node0.nr_zone_active_anon
5381 +- 34% -85.0% 809.00 +-100% numa-vmstat.node0.nr_zone_inactive_anon
4821 +- 2% +30.3% 6283 +- 15% numa-vmstat.node1
17215 +- 67% +77.7% 30591 +- 13% numa-vmstat.node1.nr_active_anon
57093 +22.3% 69850 +- 17% numa-vmstat.node1.nr_file_pages
370.00 +-116% +1061.8% 4298 +- 39% numa-vmstat.node1.nr_inactive_anon
6593 +- 2% +11.7% 7366 +- 3% numa-vmstat.node1.nr_kernel_stack
451.67 +- 97% +2725.6% 12762 +- 97% numa-vmstat.node1.nr_shmem
3824 +- 12% +88.6% 7211 +- 36% numa-vmstat.node1.nr_slab_reclaimable
13179 +- 9% +21.0% 15952 +- 11% numa-vmstat.node1.nr_slab_unreclaimable
17215 +- 67% +77.7% 30591 +- 13% numa-vmstat.node1.nr_zone_active_anon
370.00 +-116% +1061.8% 4298 +- 39% numa-vmstat.node1.nr_zone_inactive_anon
364789 +- 12% +62.8% 593926 +- 34% numa-vmstat.node1.numa_hit
239539 +- 19% +95.4% 468113 +- 43% numa-vmstat.node1.numa_local
71.00 +- 28% +42.3% 101.00 numa-vmstat.node2.nr_mlock
31285 +- 29% -65.0% 10960 +- 98% numa-vmstat.node3.nr_active_anon
23292 +- 25% -87.8% 2844 +- 19% numa-vmstat.node3.nr_anon_pages
14339 +- 52% +141.1% 34566 +- 32% numa-vmstat.node3.nr_free_cma
9151 +- 5% -9.3% 8299 +- 8% numa-vmstat.node3.nr_kernel_stack
31305 +- 29% -64.9% 10975 +- 98% numa-vmstat.node3.nr_zone_active_anon
930131 +- 3% -35.9% 596006 +- 34% numa-vmstat.node3.numa_hit
836455 +- 3% -40.9% 493947 +- 44% numa-vmstat.node3.numa_local
75182 +- 58% -83.8% 12160 +- 2% sched_debug.cfs_rq:/.load.max
6.65 +- 5% -10.6% 5.94 +- 6% sched_debug.cfs_rq:/.load_avg.avg
0.16 +- 7% +22.6% 0.20 +- 12% sched_debug.cfs_rq:/.nr_running.stddev
5.58 +- 24% +427.7% 29.42 +- 93% sched_debug.cfs_rq:/.nr_spread_over.max
0.54 +- 15% +306.8% 2.19 +- 86% sched_debug.cfs_rq:/.nr_spread_over.stddev
1.05 +- 25% -65.1% 0.37 +- 71% sched_debug.cfs_rq:/.removed.load_avg.avg
9.62 +- 11% -50.7% 4.74 +- 70% sched_debug.cfs_rq:/.removed.load_avg.stddev
48.70 +- 25% -65.1% 17.02 +- 71% sched_debug.cfs_rq:/.removed.runnable_sum.avg
444.31 +- 11% -50.7% 219.26 +- 70% sched_debug.cfs_rq:/.removed.runnable_sum.stddev
0.47 +- 13% -60.9% 0.19 +- 71% sched_debug.cfs_rq:/.removed.util_avg.avg
4.47 +- 4% -46.5% 2.39 +- 70% sched_debug.cfs_rq:/.removed.util_avg.stddev
1.64 +- 7% +22.1% 2.00 +- 13% sched_debug.cfs_rq:/.runnable_load_avg.stddev
74653 +- 59% -84.4% 11676 sched_debug.cfs_rq:/.runnable_weight.max
-119169 -491.3% 466350 +- 27% sched_debug.cfs_rq:/.spread0.avg
517161 +- 30% +145.8% 1271292 +- 23% sched_debug.cfs_rq:/.spread0.max
624.79 +- 5% -14.2% 535.76 +- 7% sched_debug.cfs_rq:/.util_est_enqueued.avg
247.91 +- 32% -99.8% 0.48 +- 8% sched_debug.cfs_rq:/.util_est_enqueued.min
179704 +- 3% +30.4% 234297 +- 16% sched_debug.cpu.avg_idle.stddev
1.56 +- 9% +24.4% 1.94 +- 14% sched_debug.cpu.cpu_load[0].stddev
1.50 +- 6% +27.7% 1.91 +- 14% sched_debug.cpu.cpu_load[1].stddev
1.45 +- 3% +30.8% 1.90 +- 14% sched_debug.cpu.cpu_load[2].stddev
1.43 +- 3% +36.1% 1.95 +- 11% sched_debug.cpu.cpu_load[3].stddev
1.55 +- 7% +43.5% 2.22 +- 7% sched_debug.cpu.cpu_load[4].stddev
10004 +- 3% -11.6% 8839 +- 3% sched_debug.cpu.curr->pid.avg
1146 +- 26% +52.2% 1745 +- 7% sched_debug.cpu.curr->pid.min
3162 +- 6% +25.4% 3966 +- 11% sched_debug.cpu.curr->pid.stddev
403738 +- 3% -11.7% 356696 +- 7% sched_debug.cpu.nr_switches.max
0.08 +- 21% +78.2% 0.14 +- 14% sched_debug.cpu.nr_uninterruptible.avg
404435 +- 3% -11.8% 356732 +- 7% sched_debug.cpu.sched_count.max
4.17 -0.3 3.87 perf-profile.calltrace.cycles-pp.kmem_cache_alloc.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
2.40 -0.2 2.17 perf-profile.calltrace.cycles-pp.vma_compute_subtree_gap.__vma_link_rb.vma_link.do_brk_flags.__x64_sys_brk
7.58 -0.2 7.36 perf-profile.calltrace.cycles-pp.perf_event_mmap.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
15.00 -0.2 14.81 perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.brk
7.83 -0.2 7.66 perf-profile.calltrace.cycles-pp.unmap_vmas.unmap_region.do_munmap.__x64_sys_brk.do_syscall_64
28.66 -0.1 28.51 perf-profile.calltrace.cycles-pp.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
2.15 -0.1 2.03 perf-profile.calltrace.cycles-pp.vma_compute_subtree_gap.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
1.07 -0.1 0.99 perf-profile.calltrace.cycles-pp.memcpy_erms.strlcpy.perf_event_mmap.do_brk_flags.__x64_sys_brk
1.03 -0.1 0.95 perf-profile.calltrace.cycles-pp.kmem_cache_free.remove_vma.do_munmap.__x64_sys_brk.do_syscall_64
7.33 -0.1 7.25 perf-profile.calltrace.cycles-pp.unmap_page_range.unmap_vmas.unmap_region.do_munmap.__x64_sys_brk
0.76 -0.1 0.69 perf-profile.calltrace.cycles-pp.__vm_enough_memory.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
11.85 -0.1 11.77 perf-profile.calltrace.cycles-pp.unmap_region.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
1.64 -0.1 1.57 perf-profile.calltrace.cycles-pp.strlcpy.perf_event_mmap.do_brk_flags.__x64_sys_brk.do_syscall_64
1.06 -0.1 0.99 perf-profile.calltrace.cycles-pp.__indirect_thunk_start.brk
0.73 -0.1 0.67 perf-profile.calltrace.cycles-pp.sync_mm_rss.unmap_page_range.unmap_vmas.unmap_region.do_munmap
4.59 -0.1 4.52 perf-profile.calltrace.cycles-pp.security_vm_enough_memory_mm.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
2.82 -0.1 2.76 perf-profile.calltrace.cycles-pp.selinux_vm_enough_memory.security_vm_enough_memory_mm.do_brk_flags.__x64_sys_brk.do_syscall_64
2.89 -0.1 2.84 perf-profile.calltrace.cycles-pp.down_write_killable.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
3.37 -0.1 3.32 perf-profile.calltrace.cycles-pp.get_unmapped_area.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
1.99 -0.0 1.94 perf-profile.calltrace.cycles-pp.cred_has_capability.selinux_vm_enough_memory.security_vm_enough_memory_mm.do_brk_flags.__x64_sys_brk
2.32 -0.0 2.27 perf-profile.calltrace.cycles-pp.perf_iterate_sb.perf_event_mmap.do_brk_flags.__x64_sys_brk.do_syscall_64
1.88 -0.0 1.84 perf-profile.calltrace.cycles-pp.security_mmap_addr.get_unmapped_area.do_brk_flags.__x64_sys_brk.do_syscall_64
0.77 -0.0 0.73 perf-profile.calltrace.cycles-pp._raw_spin_lock.unmap_page_range.unmap_vmas.unmap_region.do_munmap
1.62 -0.0 1.59 perf-profile.calltrace.cycles-pp.memset_erms.kmem_cache_alloc.do_brk_flags.__x64_sys_brk.do_syscall_64
0.81 -0.0 0.79 perf-profile.calltrace.cycles-pp.___might_sleep.down_write_killable.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.66 -0.0 0.64 perf-profile.calltrace.cycles-pp.arch_get_unmapped_area_topdown.brk
0.72 +0.0 0.74 perf-profile.calltrace.cycles-pp.do_munmap.brk
0.90 +0.0 0.93 perf-profile.calltrace.cycles-pp.___might_sleep.unmap_page_range.unmap_vmas.unmap_region.do_munmap
4.40 +0.1 4.47 perf-profile.calltrace.cycles-pp.find_vma.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
1.96 +0.1 2.09 perf-profile.calltrace.cycles-pp.vmacache_find.find_vma.do_munmap.__x64_sys_brk.do_syscall_64
0.52 +- 2% +0.2 0.68 perf-profile.calltrace.cycles-pp.__vma_link_rb.brk
0.35 +- 70% +0.2 0.54 +- 2% perf-profile.calltrace.cycles-pp.find_vma.brk
2.20 +0.3 2.50 perf-profile.calltrace.cycles-pp.remove_vma.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
64.62 +0.3 64.94 perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.brk
60.53 +0.4 60.92 perf-profile.calltrace.cycles-pp.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
63.20 +0.4 63.60 perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
3.73 +0.5 4.26 perf-profile.calltrace.cycles-pp.vma_link.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +0.6 0.56 perf-profile.calltrace.cycles-pp.free_pgtables.unmap_region.do_munmap.__x64_sys_brk.do_syscall_64
24.54 +0.6 25.14 perf-profile.calltrace.cycles-pp.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
0.00 +0.6 0.64 perf-profile.calltrace.cycles-pp.put_vma.remove_vma.do_munmap.__x64_sys_brk.do_syscall_64
0.71 +0.6 1.36 perf-profile.calltrace.cycles-pp.__vma_rb_erase.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +0.7 0.70 perf-profile.calltrace.cycles-pp._raw_write_lock.__vma_rb_erase.do_munmap.__x64_sys_brk.do_syscall_64
3.10 +0.7 3.82 perf-profile.calltrace.cycles-pp.__vma_link_rb.vma_link.do_brk_flags.__x64_sys_brk.do_syscall_64
0.00 +0.8 0.76 perf-profile.calltrace.cycles-pp._raw_write_lock.__vma_link_rb.vma_link.do_brk_flags.__x64_sys_brk
0.00 +0.8 0.85 perf-profile.calltrace.cycles-pp.__vma_merge.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
5.09 -0.5 4.62 perf-profile.children.cycles-pp.vma_compute_subtree_gap
4.54 -0.3 4.21 perf-profile.children.cycles-pp.kmem_cache_alloc
8.11 -0.2 7.89 perf-profile.children.cycles-pp.perf_event_mmap
8.05 -0.2 7.85 perf-profile.children.cycles-pp.unmap_vmas
15.01 -0.2 14.81 perf-profile.children.cycles-pp.syscall_return_via_sysret
29.20 -0.1 29.06 perf-profile.children.cycles-pp.do_brk_flags
1.11 -0.1 1.00 perf-profile.children.cycles-pp.kmem_cache_free
12.28 -0.1 12.17 perf-profile.children.cycles-pp.unmap_region
7.83 -0.1 7.74 perf-profile.children.cycles-pp.unmap_page_range
0.87 +- 3% -0.1 0.79 perf-profile.children.cycles-pp.__vm_enough_memory
1.29 -0.1 1.22 perf-profile.children.cycles-pp.__indirect_thunk_start
1.81 -0.1 1.74 perf-profile.children.cycles-pp.strlcpy
4.65 -0.1 4.58 perf-profile.children.cycles-pp.security_vm_enough_memory_mm
3.08 -0.1 3.02 perf-profile.children.cycles-pp.down_write_killable
2.88 -0.1 2.82 perf-profile.children.cycles-pp.selinux_vm_enough_memory
0.73 -0.1 0.67 perf-profile.children.cycles-pp.sync_mm_rss
3.65 -0.1 3.59 perf-profile.children.cycles-pp.get_unmapped_area
2.26 -0.1 2.20 perf-profile.children.cycles-pp.cred_has_capability
1.12 -0.1 1.07 perf-profile.children.cycles-pp.memcpy_erms
0.39 -0.0 0.35 perf-profile.children.cycles-pp.__rb_insert_augmented
2.52 -0.0 2.48 perf-profile.children.cycles-pp.perf_iterate_sb
2.13 -0.0 2.09 perf-profile.children.cycles-pp.security_mmap_addr
0.55 +- 2% -0.0 0.52 perf-profile.children.cycles-pp.unmap_single_vma
1.62 -0.0 1.59 perf-profile.children.cycles-pp.memset_erms
0.13 +- 3% -0.0 0.11 +- 4% perf-profile.children.cycles-pp.__vma_link_file
0.80 -0.0 0.77 perf-profile.children.cycles-pp._raw_spin_lock
0.43 -0.0 0.41 perf-profile.children.cycles-pp.strlen
0.07 +- 6% -0.0 0.06 +- 8% perf-profile.children.cycles-pp.should_failslab
0.43 -0.0 0.42 perf-profile.children.cycles-pp.may_expand_vm
0.15 +0.0 0.16 perf-profile.children.cycles-pp.__vma_link_list
0.45 +0.0 0.47 perf-profile.children.cycles-pp.rcu_all_qs
0.81 +0.1 0.89 perf-profile.children.cycles-pp.free_pgtables
6.35 +0.1 6.49 perf-profile.children.cycles-pp.find_vma
2.28 +0.2 2.45 perf-profile.children.cycles-pp.vmacache_find
64.66 +0.3 64.98 perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
2.42 +0.3 2.76 perf-profile.children.cycles-pp.remove_vma
61.77 +0.4 62.13 perf-profile.children.cycles-pp.__x64_sys_brk
63.40 +0.4 63.79 perf-profile.children.cycles-pp.do_syscall_64
1.27 +0.4 1.72 perf-profile.children.cycles-pp.__vma_rb_erase
4.02 +0.5 4.53 perf-profile.children.cycles-pp.vma_link
25.26 +0.6 25.89 perf-profile.children.cycles-pp.do_munmap
0.00 +0.7 0.70 perf-profile.children.cycles-pp.put_vma
3.80 +0.7 4.53 perf-profile.children.cycles-pp.__vma_link_rb
0.00 +1.2 1.24 perf-profile.children.cycles-pp.__vma_merge
0.00 +1.5 1.51 perf-profile.children.cycles-pp._raw_write_lock
5.07 -0.5 4.60 perf-profile.self.cycles-pp.vma_compute_subtree_gap
0.59 -0.2 0.38 perf-profile.self.cycles-pp.remove_vma
15.01 -0.2 14.81 perf-profile.self.cycles-pp.syscall_return_via_sysret
3.15 -0.2 2.96 perf-profile.self.cycles-pp.do_munmap
0.98 -0.1 0.87 perf-profile.self.cycles-pp.__vma_rb_erase
1.10 -0.1 0.99 perf-profile.self.cycles-pp.kmem_cache_free
0.68 -0.1 0.58 perf-profile.self.cycles-pp.__vm_enough_memory
0.42 -0.1 0.33 perf-profile.self.cycles-pp.unmap_vmas
3.62 -0.1 3.53 perf-profile.self.cycles-pp.perf_event_mmap
1.41 -0.1 1.34 perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
1.29 -0.1 1.22 perf-profile.self.cycles-pp.__indirect_thunk_start
0.73 -0.1 0.66 perf-profile.self.cycles-pp.sync_mm_rss
2.96 -0.1 2.90 perf-profile.self.cycles-pp.__x64_sys_brk
3.24 -0.1 3.19 perf-profile.self.cycles-pp.brk
1.11 -0.0 1.07 perf-profile.self.cycles-pp.memcpy_erms
0.53 +- 3% -0.0 0.49 +- 2% perf-profile.self.cycles-pp.vma_link
0.73 -0.0 0.69 perf-profile.self.cycles-pp.unmap_region
1.66 -0.0 1.61 perf-profile.self.cycles-pp.down_write_killable
0.39 -0.0 0.35 perf-profile.self.cycles-pp.__rb_insert_augmented
1.74 -0.0 1.71 perf-profile.self.cycles-pp.kmem_cache_alloc
0.55 +- 2% -0.0 0.52 perf-profile.self.cycles-pp.unmap_single_vma
1.61 -0.0 1.59 perf-profile.self.cycles-pp.memset_erms
0.80 -0.0 0.77 perf-profile.self.cycles-pp._raw_spin_lock
0.13 -0.0 0.11 +- 4% perf-profile.self.cycles-pp.__vma_link_file
0.43 -0.0 0.41 perf-profile.self.cycles-pp.strlen
0.07 +- 6% -0.0 0.06 +- 8% perf-profile.self.cycles-pp.should_failslab
0.81 -0.0 0.79 perf-profile.self.cycles-pp.tlb_finish_mmu
0.15 +0.0 0.16 perf-profile.self.cycles-pp.__vma_link_list
0.45 +0.0 0.47 perf-profile.self.cycles-pp.rcu_all_qs
0.71 +0.0 0.72 perf-profile.self.cycles-pp.strlcpy
0.51 +0.1 0.56 perf-profile.self.cycles-pp.free_pgtables
1.41 +0.1 1.48 perf-profile.self.cycles-pp.__vma_link_rb
2.27 +0.2 2.44 perf-profile.self.cycles-pp.vmacache_find
0.00 +0.7 0.69 perf-profile.self.cycles-pp.put_vma
0.00 +1.2 1.23 perf-profile.self.cycles-pp.__vma_merge
0.00 +1.5 1.50 perf-profile.self.cycles-pp._raw_write_lock
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/always/brk1/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
:3 33% 1:3 dmesg.WARNING:stack_going_in_the_wrong_direction?ip=schedule_tail/0x
:3 33% 1:3 kmsg.DHCP/BOOTP:Reply_not_for_us_on_eth#,op[#]xid[#]
%stddev %change %stddev
\ | \
998475 -2.2% 976893 will-it-scale.per_process_ops
625.87 -2.3% 611.42 will-it-scale.time.elapsed_time
625.87 -2.3% 611.42 will-it-scale.time.elapsed_time.max
8158 -1.9% 8000 will-it-scale.time.maximum_resident_set_size
18.42 +- 2% -11.9% 16.24 will-it-scale.time.user_time
34349225 +- 13% -14.5% 29371024 +- 17% will-it-scale.time.voluntary_context_switches
1.919e+08 -2.2% 1.877e+08 will-it-scale.workload
1639 +- 23% -18.4% 1337 +- 30% meminfo.Mlocked
17748 +- 82% +103.1% 36051 numa-numastat.node3.other_node
33410486 +- 14% -14.8% 28449258 +- 18% cpuidle.C1.usage
698749 +- 15% -18.0% 573307 +- 20% cpuidle.POLL.usage
3013702 +- 14% -15.1% 2559405 +- 17% softirqs.SCHED
54361293 +- 2% -19.0% 44044816 +- 2% softirqs.TIMER
33408303 +- 14% -14.9% 28447123 +- 18% turbostat.C1
0.34 +- 16% -52.0% 0.16 +- 15% turbostat.Pkg%pc2
1310 +- 74% +412.1% 6710 +- 58% irq_exception_noise.__do_page_fault.samples
3209 +- 74% +281.9% 12258 +- 53% irq_exception_noise.__do_page_fault.sum
600.67 +-132% -96.0% 24.00 +- 23% irq_exception_noise.irq_nr
99557 +- 7% -24.0% 75627 +- 7% irq_exception_noise.softirq_nr
41424 +- 9% -24.6% 31253 +- 6% irq_exception_noise.softirq_time
625.87 -2.3% 611.42 time.elapsed_time
625.87 -2.3% 611.42 time.elapsed_time.max
8158 -1.9% 8000 time.maximum_resident_set_size
18.42 +- 2% -11.9% 16.24 time.user_time
34349225 +- 13% -14.5% 29371024 +- 17% time.voluntary_context_switches
988.00 +- 8% +14.5% 1131 +- 2% slabinfo.Acpi-ParseExt.active_objs
988.00 +- 8% +14.5% 1131 +- 2% slabinfo.Acpi-ParseExt.num_objs
2384 +- 3% +21.1% 2888 +- 11% slabinfo.pool_workqueue.active_objs
2474 +- 2% +20.4% 2979 +- 11% slabinfo.pool_workqueue.num_objs
490.33 +- 10% -19.2% 396.00 +- 11% slabinfo.secpath_cache.active_objs
490.33 +- 10% -19.2% 396.00 +- 11% slabinfo.secpath_cache.num_objs
1123 +- 7% +14.2% 1282 +- 3% slabinfo.skbuff_fclone_cache.active_objs
1123 +- 7% +14.2% 1282 +- 3% slabinfo.skbuff_fclone_cache.num_objs
1.09 -0.0 1.07 perf-stat.branch-miss-rate%
2.691e+11 -2.4% 2.628e+11 perf-stat.branch-misses
71981351 +- 12% -13.8% 62013509 +- 16% perf-stat.context-switches
1.697e+13 +1.1% 1.715e+13 perf-stat.dTLB-stores
2.36 +- 29% +4.4 6.76 +- 11% perf-stat.iTLB-load-miss-rate%
5.21e+08 +- 28% +194.8% 1.536e+09 +- 10% perf-stat.iTLB-load-misses
239983 +- 24% -68.4% 75819 +- 11% perf-stat.instructions-per-iTLB-miss
3295653 +- 2% -6.3% 3088753 +- 3% perf-stat.node-stores
606239 +1.1% 612799 perf-stat.path-length
3755 +- 28% -37.5% 2346 +- 52% sched_debug.cfs_rq:/.exec_clock.stddev
10.45 +- 4% +24.3% 12.98 +- 18% sched_debug.cfs_rq:/.load_avg.stddev
6243 +- 46% -38.6% 3831 +- 78% sched_debug.cpu.load.stddev
867.80 +- 7% +25.3% 1087 +- 6% sched_debug.cpu.nr_load_updates.stddev
395898 +- 3% -11.1% 352071 +- 7% sched_debug.cpu.nr_switches.max
-13.33 -21.1% -10.52 sched_debug.cpu.nr_uninterruptible.min
395674 +- 3% -11.1% 351762 +- 7% sched_debug.cpu.sched_count.max
33152 +- 4% -12.8% 28899 sched_debug.cpu.ttwu_count.min
0.03 +- 20% +77.7% 0.05 +- 15% sched_debug.rt_rq:/.rt_time.max
89523 +1.8% 91099 proc-vmstat.nr_active_anon
409.67 +- 23% -18.4% 334.33 +- 30% proc-vmstat.nr_mlock
89530 +1.8% 91117 proc-vmstat.nr_zone_active_anon
2337130 -2.2% 2286775 proc-vmstat.numa_hit
2229090 -2.3% 2178626 proc-vmstat.numa_local
8460 +- 39% -75.5% 2076 +- 53% proc-vmstat.numa_pages_migrated
28643 +- 55% -83.5% 4727 +- 58% proc-vmstat.numa_pte_updates
2695806 -1.8% 2646639 proc-vmstat.pgfault
2330191 -2.1% 2281197 proc-vmstat.pgfree
8460 +- 39% -75.5% 2076 +- 53% proc-vmstat.pgmigrate_success
237651 +- 2% +31.3% 312092 +- 16% numa-meminfo.node0.FilePages
8059 +- 2% +10.7% 8925 +- 7% numa-meminfo.node0.KernelStack
6830 +- 25% +48.8% 10164 +- 35% numa-meminfo.node0.Mapped
1612 +- 21% +70.0% 2740 +- 19% numa-meminfo.node0.PageTables
10772 +- 65% +679.4% 83962 +- 59% numa-meminfo.node0.Shmem
163195 +- 15% -36.9% 103036 +- 32% numa-meminfo.node1.Active
163195 +- 15% -36.9% 103036 +- 32% numa-meminfo.node1.Active(anon)
1730 +- 4% +33.9% 2317 +- 14% numa-meminfo.node1.PageTables
55778 +- 19% +32.5% 73910 +- 8% numa-meminfo.node1.SUnreclaim
2671 +- 16% -45.0% 1469 +- 15% numa-meminfo.node2.PageTables
61537 +- 13% -17.7% 50647 +- 3% numa-meminfo.node2.SUnreclaim
48644 +- 94% +149.8% 121499 +- 11% numa-meminfo.node3.Active
48440 +- 94% +150.4% 121295 +- 11% numa-meminfo.node3.Active(anon)
11832 +- 79% -91.5% 1008 +- 67% numa-meminfo.node3.Inactive
11597 +- 82% -93.3% 772.00 +- 82% numa-meminfo.node3.Inactive(anon)
10389 +- 32% -43.0% 5921 +- 6% numa-meminfo.node3.Mapped
33704 +- 24% -44.2% 18792 +- 15% numa-meminfo.node3.SReclaimable
104733 +- 14% -25.3% 78275 +- 8% numa-meminfo.node3.Slab
139329 +-133% -99.8% 241.67 +- 79% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_do_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open.do_syscall_64
5403 +-139% -97.5% 137.67 +- 71% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
165968 +-101% -61.9% 63304 +- 58% latency_stats.avg.max
83.00 +12810.4% 10715 +-140% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_access.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat.filename_lookup
102.67 +- 6% +18845.5% 19450 +-140% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
136.33 +- 16% +25043.5% 34279 +-141% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.__lookup_slow.lookup_slow.walk_component.path_lookupat.filename_lookup
18497 +-141% -100.0% 0.00 latency_stats.max.call_rwsem_down_write_failed_killable.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe
140500 +-131% -99.8% 247.00 +- 78% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_do_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open.do_syscall_64
5403 +-139% -97.5% 137.67 +- 71% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
87.33 +- 5% +23963.0% 21015 +-140% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_access.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat.filename_lookup
136.33 +- 16% +25043.5% 34279 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.__lookup_slow.lookup_slow.walk_component.path_lookupat.filename_lookup
149.33 +- 14% +25485.9% 38208 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
18761 +-141% -100.0% 0.00 latency_stats.sum.call_rwsem_down_write_failed_killable.vm_mmap_pgoff.ksys_mmap_pgoff.do_syscall_64.entry_SYSCALL_64_after_hwframe
23363 +-114% -100.0% 0.00 latency_stats.sum.call_rwsem_down_read_failed.__do_page_fault.do_page_fault.page_fault.__get_user_8.exit_robust_list.mm_release.do_exit.do_group_exit.get_signal.do_signal.exit_to_usermode_loop
144810 +-125% -99.8% 326.67 +- 70% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_do_create.nfs3_proc_create.nfs_create.path_openat.do_filp_open.do_sys_open.do_syscall_64
5403 +-139% -97.5% 137.67 +- 71% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.path_openat.do_filp_open.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
59698 +- 98% -78.0% 13110 +-141% latency_stats.sum.call_rwsem_down_read_failed.do_exit.do_group_exit.get_signal.do_signal.exit_to_usermode_loop.do_syscall_64.entry_SYSCALL_64_after_hwframe
166.33 +12768.5% 21404 +-140% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_access.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat.filename_lookup
825.00 +- 6% +18761.7% 155609 +-140% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
136.33 +- 16% +25043.5% 34279 +-141% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup.__lookup_slow.lookup_slow.walk_component.path_lookupat.filename_lookup
59412 +- 2% +31.3% 78021 +- 16% numa-vmstat.node0.nr_file_pages
8059 +- 2% +10.7% 8923 +- 7% numa-vmstat.node0.nr_kernel_stack
1701 +- 25% +49.1% 2536 +- 35% numa-vmstat.node0.nr_mapped
402.33 +- 21% +70.0% 684.00 +- 19% numa-vmstat.node0.nr_page_table_pages
2692 +- 65% +679.5% 20988 +- 59% numa-vmstat.node0.nr_shmem
622587 +- 36% +37.7% 857545 +- 13% numa-vmstat.node0.numa_local
40797 +- 15% -36.9% 25757 +- 32% numa-vmstat.node1.nr_active_anon
432.00 +- 4% +33.9% 578.33 +- 14% numa-vmstat.node1.nr_page_table_pages
13944 +- 19% +32.5% 18477 +- 8% numa-vmstat.node1.nr_slab_unreclaimable
40797 +- 15% -36.9% 25757 +- 32% numa-vmstat.node1.nr_zone_active_anon
625073 +- 26% +29.4% 808657 +- 18% numa-vmstat.node1.numa_hit
503969 +- 34% +39.2% 701446 +- 23% numa-vmstat.node1.numa_local
137.33 +- 40% -49.0% 70.00 +- 29% numa-vmstat.node2.nr_mlock
667.67 +- 17% -45.1% 366.33 +- 15% numa-vmstat.node2.nr_page_table_pages
15384 +- 13% -17.7% 12662 +- 3% numa-vmstat.node2.nr_slab_unreclaimable
12114 +- 94% +150.3% 30326 +- 11% numa-vmstat.node3.nr_active_anon
2887 +- 83% -93.4% 190.00 +- 82% numa-vmstat.node3.nr_inactive_anon
2632 +- 30% -39.2% 1600 +- 5% numa-vmstat.node3.nr_mapped
101.00 -30.0% 70.67 +- 29% numa-vmstat.node3.nr_mlock
8425 +- 24% -44.2% 4697 +- 15% numa-vmstat.node3.nr_slab_reclaimable
12122 +- 94% +150.3% 30346 +- 11% numa-vmstat.node3.nr_zone_active_anon
2887 +- 83% -93.4% 190.00 +- 82% numa-vmstat.node3.nr_zone_inactive_anon
106945 +- 13% +17.4% 125554 numa-vmstat.node3.numa_other
4.17 -0.3 3.82 perf-profile.calltrace.cycles-pp.kmem_cache_alloc.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
15.02 -0.3 14.77 perf-profile.calltrace.cycles-pp.syscall_return_via_sysret.brk
2.42 -0.2 2.18 perf-profile.calltrace.cycles-pp.vma_compute_subtree_gap.__vma_link_rb.vma_link.do_brk_flags.__x64_sys_brk
7.60 -0.2 7.39 perf-profile.calltrace.cycles-pp.perf_event_mmap.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
7.79 -0.2 7.63 perf-profile.calltrace.cycles-pp.unmap_vmas.unmap_region.do_munmap.__x64_sys_brk.do_syscall_64
0.82 +- 9% -0.1 0.68 perf-profile.calltrace.cycles-pp.__vm_enough_memory.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
2.13 -0.1 2.00 perf-profile.calltrace.cycles-pp.vma_compute_subtree_gap.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
1.05 -0.1 0.95 perf-profile.calltrace.cycles-pp.kmem_cache_free.remove_vma.do_munmap.__x64_sys_brk.do_syscall_64
7.31 -0.1 7.21 perf-profile.calltrace.cycles-pp.unmap_page_range.unmap_vmas.unmap_region.do_munmap.__x64_sys_brk
0.74 -0.1 0.67 perf-profile.calltrace.cycles-pp.sync_mm_rss.unmap_page_range.unmap_vmas.unmap_region.do_munmap
1.06 -0.1 1.00 perf-profile.calltrace.cycles-pp.memcpy_erms.strlcpy.perf_event_mmap.do_brk_flags.__x64_sys_brk
3.38 -0.1 3.33 perf-profile.calltrace.cycles-pp.get_unmapped_area.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
1.05 -0.0 1.00 +- 2% perf-profile.calltrace.cycles-pp.__indirect_thunk_start.brk
2.34 -0.0 2.29 perf-profile.calltrace.cycles-pp.perf_iterate_sb.perf_event_mmap.do_brk_flags.__x64_sys_brk.do_syscall_64
1.64 -0.0 1.59 perf-profile.calltrace.cycles-pp.strlcpy.perf_event_mmap.do_brk_flags.__x64_sys_brk.do_syscall_64
1.89 -0.0 1.86 perf-profile.calltrace.cycles-pp.security_mmap_addr.get_unmapped_area.do_brk_flags.__x64_sys_brk.do_syscall_64
0.76 -0.0 0.73 perf-profile.calltrace.cycles-pp._raw_spin_lock.unmap_page_range.unmap_vmas.unmap_region.do_munmap
0.57 +- 2% -0.0 0.55 perf-profile.calltrace.cycles-pp.selinux_mmap_addr.security_mmap_addr.get_unmapped_area.do_brk_flags.__x64_sys_brk
0.54 +- 2% +0.0 0.56 perf-profile.calltrace.cycles-pp.do_brk_flags.brk
0.72 +0.0 0.76 +- 2% perf-profile.calltrace.cycles-pp.do_munmap.brk
4.38 +0.1 4.43 perf-profile.calltrace.cycles-pp.find_vma.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
1.96 +0.1 2.04 perf-profile.calltrace.cycles-pp.vmacache_find.find_vma.do_munmap.__x64_sys_brk.do_syscall_64
0.53 +0.2 0.68 perf-profile.calltrace.cycles-pp.__vma_link_rb.brk
2.21 +0.3 2.51 perf-profile.calltrace.cycles-pp.remove_vma.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
64.44 +0.5 64.90 perf-profile.calltrace.cycles-pp.entry_SYSCALL_64_after_hwframe.brk
63.04 +0.5 63.54 perf-profile.calltrace.cycles-pp.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
60.37 +0.5 60.88 perf-profile.calltrace.cycles-pp.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
3.75 +0.5 4.29 perf-profile.calltrace.cycles-pp.vma_link.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +0.6 0.57 perf-profile.calltrace.cycles-pp.free_pgtables.unmap_region.do_munmap.__x64_sys_brk.do_syscall_64
0.00 +0.6 0.64 perf-profile.calltrace.cycles-pp.put_vma.remove_vma.do_munmap.__x64_sys_brk.do_syscall_64
0.72 +0.7 1.37 perf-profile.calltrace.cycles-pp.__vma_rb_erase.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
24.42 +0.7 25.08 perf-profile.calltrace.cycles-pp.do_munmap.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe.brk
0.00 +0.7 0.71 perf-profile.calltrace.cycles-pp._raw_write_lock.__vma_rb_erase.do_munmap.__x64_sys_brk.do_syscall_64
3.12 +0.7 3.84 perf-profile.calltrace.cycles-pp.__vma_link_rb.vma_link.do_brk_flags.__x64_sys_brk.do_syscall_64
0.00 +0.8 0.77 perf-profile.calltrace.cycles-pp._raw_write_lock.__vma_link_rb.vma_link.do_brk_flags.__x64_sys_brk
0.00 +0.9 0.85 perf-profile.calltrace.cycles-pp.__vma_merge.do_brk_flags.__x64_sys_brk.do_syscall_64.entry_SYSCALL_64_after_hwframe
5.10 -0.5 4.60 perf-profile.children.cycles-pp.vma_compute_subtree_gap
4.53 -0.3 4.18 perf-profile.children.cycles-pp.kmem_cache_alloc
15.03 -0.3 14.77 perf-profile.children.cycles-pp.syscall_return_via_sysret
8.13 -0.2 7.92 perf-profile.children.cycles-pp.perf_event_mmap
8.01 -0.2 7.81 perf-profile.children.cycles-pp.unmap_vmas
0.97 +- 14% -0.2 0.78 perf-profile.children.cycles-pp.__vm_enough_memory
1.13 -0.1 1.00 perf-profile.children.cycles-pp.kmem_cache_free
7.82 -0.1 7.70 perf-profile.children.cycles-pp.unmap_page_range
12.23 -0.1 12.13 perf-profile.children.cycles-pp.unmap_region
0.74 -0.1 0.67 perf-profile.children.cycles-pp.sync_mm_rss
3.06 -0.1 3.00 perf-profile.children.cycles-pp.down_write_killable
0.40 +- 2% -0.1 0.34 perf-profile.children.cycles-pp.__rb_insert_augmented
1.29 -0.1 1.23 perf-profile.children.cycles-pp.__indirect_thunk_start
2.54 -0.1 2.49 perf-profile.children.cycles-pp.perf_iterate_sb
3.66 -0.0 3.61 perf-profile.children.cycles-pp.get_unmapped_area
1.80 -0.0 1.75 perf-profile.children.cycles-pp.strlcpy
0.53 +- 2% -0.0 0.49 +- 2% perf-profile.children.cycles-pp.cap_capable
1.57 -0.0 1.53 perf-profile.children.cycles-pp.arch_get_unmapped_area_topdown
1.11 -0.0 1.08 perf-profile.children.cycles-pp.memcpy_erms
0.13 -0.0 0.10 perf-profile.children.cycles-pp.__vma_link_file
0.55 -0.0 0.52 perf-profile.children.cycles-pp.unmap_single_vma
1.47 -0.0 1.44 perf-profile.children.cycles-pp.cap_vm_enough_memory
2.14 -0.0 2.12 perf-profile.children.cycles-pp.security_mmap_addr
0.32 -0.0 0.30 perf-profile.children.cycles-pp.userfaultfd_unmap_complete
1.25 -0.0 1.23 perf-profile.children.cycles-pp.up_write
0.50 -0.0 0.49 perf-profile.children.cycles-pp.userfaultfd_unmap_prep
0.27 -0.0 0.26 perf-profile.children.cycles-pp.tlb_flush_mmu_free
1.14 -0.0 1.12 perf-profile.children.cycles-pp.__might_sleep
0.07 -0.0 0.06 perf-profile.children.cycles-pp.should_failslab
0.72 +0.0 0.74 perf-profile.children.cycles-pp._cond_resched
0.45 +0.0 0.47 perf-profile.children.cycles-pp.rcu_all_qs
0.15 +- 3% +0.0 0.17 +- 4% perf-profile.children.cycles-pp.__vma_link_list
0.15 +- 5% +0.0 0.18 +- 5% perf-profile.children.cycles-pp.tick_sched_timer
0.05 +- 8% +0.1 0.12 +- 17% perf-profile.children.cycles-pp.perf_mux_hrtimer_handler
0.80 +0.1 0.89 perf-profile.children.cycles-pp.free_pgtables
0.22 +- 7% +0.1 0.31 +- 9% perf-profile.children.cycles-pp.__hrtimer_run_queues
0.00 +0.1 0.11 +- 15% perf-profile.children.cycles-pp.clockevents_program_event
6.34 +0.1 6.47 perf-profile.children.cycles-pp.find_vma
2.27 +0.1 2.40 perf-profile.children.cycles-pp.vmacache_find
0.40 +- 4% +0.2 0.58 +- 5% perf-profile.children.cycles-pp.apic_timer_interrupt
0.40 +- 4% +0.2 0.58 +- 5% perf-profile.children.cycles-pp.smp_apic_timer_interrupt
0.37 +- 4% +0.2 0.54 +- 5% perf-profile.children.cycles-pp.hrtimer_interrupt
0.00 +0.2 0.19 +- 12% perf-profile.children.cycles-pp.ktime_get
2.42 +0.3 2.77 perf-profile.children.cycles-pp.remove_vma
64.49 +0.5 64.94 perf-profile.children.cycles-pp.entry_SYSCALL_64_after_hwframe
1.27 +0.5 1.73 perf-profile.children.cycles-pp.__vma_rb_erase
61.62 +0.5 62.10 perf-profile.children.cycles-pp.__x64_sys_brk
63.24 +0.5 63.74 perf-profile.children.cycles-pp.do_syscall_64
4.03 +0.5 4.56 perf-profile.children.cycles-pp.vma_link
0.00 +0.7 0.69 perf-profile.children.cycles-pp.put_vma
25.13 +0.7 25.84 perf-profile.children.cycles-pp.do_munmap
3.83 +0.7 4.56 perf-profile.children.cycles-pp.__vma_link_rb
0.00 +1.2 1.25 perf-profile.children.cycles-pp.__vma_merge
0.00 +1.5 1.53 perf-profile.children.cycles-pp._raw_write_lock
5.08 -0.5 4.58 perf-profile.self.cycles-pp.vma_compute_subtree_gap
15.03 -0.3 14.77 perf-profile.self.cycles-pp.syscall_return_via_sysret
0.59 -0.2 0.39 perf-profile.self.cycles-pp.remove_vma
0.72 +- 7% -0.1 0.58 perf-profile.self.cycles-pp.__vm_enough_memory
1.12 -0.1 0.99 perf-profile.self.cycles-pp.kmem_cache_free
3.11 -0.1 2.99 perf-profile.self.cycles-pp.do_munmap
0.99 -0.1 0.88 perf-profile.self.cycles-pp.__vma_rb_erase
3.63 -0.1 3.52 perf-profile.self.cycles-pp.perf_event_mmap
3.26 -0.1 3.17 perf-profile.self.cycles-pp.brk
0.41 +- 2% -0.1 0.33 perf-profile.self.cycles-pp.unmap_vmas
0.74 -0.1 0.67 perf-profile.self.cycles-pp.sync_mm_rss
1.75 -0.1 1.68 perf-profile.self.cycles-pp.kmem_cache_alloc
0.40 +- 2% -0.1 0.34 perf-profile.self.cycles-pp.__rb_insert_augmented
1.29 +- 2% -0.1 1.23 perf-profile.self.cycles-pp.__indirect_thunk_start
0.73 -0.0 0.68 +- 2% perf-profile.self.cycles-pp.unmap_region
0.53 -0.0 0.49 perf-profile.self.cycles-pp.vma_link
1.40 -0.0 1.35 perf-profile.self.cycles-pp.entry_SYSCALL_64_after_hwframe
5.22 -0.0 5.18 perf-profile.self.cycles-pp.unmap_page_range
0.53 +- 2% -0.0 0.49 +- 2% perf-profile.self.cycles-pp.cap_capable
1.11 -0.0 1.07 perf-profile.self.cycles-pp.memcpy_erms
1.86 -0.0 1.82 perf-profile.self.cycles-pp.perf_iterate_sb
1.30 -0.0 1.27 perf-profile.self.cycles-pp.arch_get_unmapped_area_topdown
0.13 -0.0 0.10 perf-profile.self.cycles-pp.__vma_link_file
0.55 -0.0 0.52 perf-profile.self.cycles-pp.unmap_single_vma
0.74 -0.0 0.72 perf-profile.self.cycles-pp.selinux_mmap_addr
0.32 -0.0 0.30 perf-profile.self.cycles-pp.userfaultfd_unmap_complete
1.13 -0.0 1.12 perf-profile.self.cycles-pp.__might_sleep
1.24 -0.0 1.23 perf-profile.self.cycles-pp.up_write
0.50 -0.0 0.49 perf-profile.self.cycles-pp.userfaultfd_unmap_prep
0.27 -0.0 0.26 perf-profile.self.cycles-pp.tlb_flush_mmu_free
0.07 -0.0 0.06 perf-profile.self.cycles-pp.should_failslab
0.45 +0.0 0.47 perf-profile.self.cycles-pp.rcu_all_qs
0.71 +0.0 0.73 perf-profile.self.cycles-pp.strlcpy
0.15 +- 3% +0.0 0.17 +- 4% perf-profile.self.cycles-pp.__vma_link_list
0.51 +0.1 0.57 perf-profile.self.cycles-pp.free_pgtables
1.40 +0.1 1.49 perf-profile.self.cycles-pp.__vma_link_rb
2.27 +0.1 2.39 perf-profile.self.cycles-pp.vmacache_find
0.00 +0.2 0.18 +- 12% perf-profile.self.cycles-pp.ktime_get
0.00 +0.7 0.69 perf-profile.self.cycles-pp.put_vma
0.00 +1.2 1.24 perf-profile.self.cycles-pp.__vma_merge
0.00 +1.5 1.52 perf-profile.self.cycles-pp._raw_write_lock
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/always/page_fault2/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
:3 33% 1:3 dmesg.WARNING:at#for_ip_native_iret/0x
1:3 -33% :3 dmesg.WARNING:stack_going_in_the_wrong_direction?ip=__schedule/0x
:3 33% 1:3 dmesg.WARNING:stack_going_in_the_wrong_direction?ip=__slab_free/0x
1:3 -33% :3 kmsg.DHCP/BOOTP:Reply_not_for_us_on_eth#,op[#]xid[#]
3:3 -100% :3 kmsg.pstore:crypto_comp_decompress_failed,ret=
3:3 -100% :3 kmsg.pstore:decompression_failed
2:3 4% 2:3 perf-profile.calltrace.cycles-pp.sync_regs.error_entry
5:3 7% 5:3 perf-profile.calltrace.cycles-pp.error_entry
5:3 7% 5:3 perf-profile.children.cycles-pp.error_entry
2:3 3% 2:3 perf-profile.self.cycles-pp.error_entry
%stddev %change %stddev
\ | \
8281 +- 2% -18.8% 6728 will-it-scale.per_thread_ops
92778 +- 2% +17.6% 109080 will-it-scale.time.involuntary_context_switches
21954366 +- 3% +4.1% 22857988 +- 2% will-it-scale.time.maximum_resident_set_size
4.81e+08 +- 2% -18.9% 3.899e+08 will-it-scale.time.minor_page_faults
5804 +12.2% 6512 will-it-scale.time.percent_of_cpu_this_job_got
34918 +12.2% 39193 will-it-scale.time.system_time
5638528 +- 2% -15.3% 4778392 will-it-scale.time.voluntary_context_switches
15846405 -2.0% 15531034 will-it-scale.workload
2818137 +1.5% 2861500 interrupts.CAL:Function_call_interrupts
3.33 +- 28% -60.0% 1.33 +- 93% irq_exception_noise.irq_time
2866 +23.9% 3552 +- 2% kthread_noise.total_time
5589674 +- 14% +31.4% 7344810 +- 6% meminfo.DirectMap2M
31169 -16.9% 25906 uptime.idle
25242 +- 4% -14.2% 21654 +- 6% vmstat.system.cs
7055 -11.6% 6237 boot-time.idle
21.12 +19.3% 25.19 +- 9% boot-time.kernel_boot
20.03 +- 2% -3.7 16.38 mpstat.cpu.idle%
0.00 +- 8% -0.0 0.00 +- 4% mpstat.cpu.iowait%
7284147 +- 2% -16.4% 6092495 softirqs.RCU
5350756 +- 2% -10.9% 4769417 +- 4% softirqs.SCHED
42933 +- 21% -28.2% 30807 +- 7% numa-meminfo.node2.SReclaimable
63219 +- 13% -16.6% 52717 +- 6% numa-meminfo.node2.SUnreclaim
106153 +- 16% -21.3% 83525 +- 5% numa-meminfo.node2.Slab
247154 +- 4% -7.6% 228415 numa-meminfo.node3.Unevictable
11904 +- 4% +17.1% 13945 +- 8% numa-vmstat.node0
2239 +- 22% -26.6% 1644 +- 2% numa-vmstat.node2.nr_mapped
10728 +- 21% -28.2% 7701 +- 7% numa-vmstat.node2.nr_slab_reclaimable
15803 +- 13% -16.6% 13179 +- 6% numa-vmstat.node2.nr_slab_unreclaimable
61788 +- 4% -7.6% 57103 numa-vmstat.node3.nr_unevictable
61788 +- 4% -7.6% 57103 numa-vmstat.node3.nr_zone_unevictable
92778 +- 2% +17.6% 109080 time.involuntary_context_switches
21954366 +- 3% +4.1% 22857988 +- 2% time.maximum_resident_set_size
4.81e+08 +- 2% -18.9% 3.899e+08 time.minor_page_faults
5804 +12.2% 6512 time.percent_of_cpu_this_job_got
34918 +12.2% 39193 time.system_time
5638528 +- 2% -15.3% 4778392 time.voluntary_context_switches
3942289 +- 2% -10.5% 3528902 +- 2% cpuidle.C1.time
242290 -14.2% 207992 cpuidle.C1.usage
1.64e+09 +- 2% -15.7% 1.381e+09 cpuidle.C1E.time
4621281 +- 2% -14.7% 3939757 cpuidle.C1E.usage
2.115e+10 +- 2% -18.5% 1.723e+10 cpuidle.C6.time
24771099 +- 2% -18.0% 20305766 cpuidle.C6.usage
1210810 +- 4% -17.6% 997270 +- 2% cpuidle.POLL.time
18742 +- 3% -17.0% 15559 +- 2% cpuidle.POLL.usage
4135 +-141% -100.0% 0.00 latency_stats.avg.x86_reserve_hardware.x86_pmu_event_init.perf_try_init_event.perf_event_alloc.__do_sys_perf_event_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
33249 +-129% -100.0% 0.00 latency_stats.max.call_rwsem_down_read_failed.m_start.seq_read.__vfs_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
4135 +-141% -100.0% 0.00 latency_stats.max.x86_reserve_hardware.x86_pmu_event_init.perf_try_init_event.perf_event_alloc.__do_sys_perf_event_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
65839 +-116% -100.0% 0.00 latency_stats.sum.call_rwsem_down_read_failed.m_start.seq_read.__vfs_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
4135 +-141% -100.0% 0.00 latency_stats.sum.x86_reserve_hardware.x86_pmu_event_init.perf_try_init_event.perf_event_alloc.__do_sys_perf_event_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
8387 +-122% -90.9% 767.00 +- 13% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
263970 +- 10% -68.6% 82994 +- 3% latency_stats.sum.do_syslog.kmsg_read.proc_reg_read.__vfs_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
6173 +- 77% +173.3% 16869 +- 98% latency_stats.sum.pipe_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
101.33 -4.6% 96.67 proc-vmstat.nr_anon_transparent_hugepages
39967 -1.8% 39241 proc-vmstat.nr_slab_reclaimable
67166 -2.4% 65522 proc-vmstat.nr_slab_unreclaimable
237743 -3.9% 228396 proc-vmstat.nr_unevictable
237743 -3.9% 228396 proc-vmstat.nr_zone_unevictable
4.807e+09 -2.0% 4.71e+09 proc-vmstat.numa_hit
4.807e+09 -2.0% 4.71e+09 proc-vmstat.numa_local
4.791e+09 -2.1% 4.69e+09 proc-vmstat.pgalloc_normal
4.783e+09 -2.0% 4.685e+09 proc-vmstat.pgfault
4.807e+09 -2.0% 4.709e+09 proc-vmstat.pgfree
1753 +4.6% 1833 turbostat.Avg_MHz
239445 -14.1% 205783 turbostat.C1
4617105 +- 2% -14.8% 3934693 turbostat.C1E
1.40 +- 2% -0.2 1.18 turbostat.C1E%
24764661 +- 2% -18.0% 20297643 turbostat.C6
18.09 +- 2% -3.4 14.74 turbostat.C6%
7.53 +- 2% -17.1% 6.24 turbostat.CPU%c1
11.88 +- 2% -19.1% 9.61 turbostat.CPU%c6
7.62 +- 3% -20.8% 6.04 turbostat.Pkg%pc2
388.30 +1.5% 393.93 turbostat.PkgWatt
390974 +- 8% +35.8% 530867 +- 11% sched_debug.cfs_rq:/.min_vruntime.stddev
-1754042 +75.7% -3081270 sched_debug.cfs_rq:/.spread0.min
388140 +- 8% +36.2% 528494 +- 11% sched_debug.cfs_rq:/.spread0.stddev
542.30 +- 3% -10.0% 488.21 +- 3% sched_debug.cfs_rq:/.util_avg.min
53.35 +- 16% +48.7% 79.35 +- 12% sched_debug.cfs_rq:/.util_est_enqueued.avg
30520 +- 6% -15.2% 25883 +- 12% sched_debug.cpu.nr_switches.avg
473770 +- 27% -37.4% 296623 +- 32% sched_debug.cpu.nr_switches.max
17077 +- 2% -15.1% 14493 sched_debug.cpu.nr_switches.min
30138 +- 6% -15.0% 25606 +- 12% sched_debug.cpu.sched_count.avg
472345 +- 27% -37.2% 296419 +- 32% sched_debug.cpu.sched_count.max
16858 +- 2% -15.2% 14299 sched_debug.cpu.sched_count.min
8358 +- 2% -15.5% 7063 sched_debug.cpu.sched_goidle.avg
12225 -13.6% 10565 sched_debug.cpu.sched_goidle.max
8032 +- 2% -16.0% 6749 sched_debug.cpu.sched_goidle.min
14839 +- 6% -15.3% 12568 +- 12% sched_debug.cpu.ttwu_count.avg
235115 +- 28% -38.3% 145175 +- 31% sched_debug.cpu.ttwu_count.max
7627 +- 3% -15.9% 6413 +- 2% sched_debug.cpu.ttwu_count.min
226299 +- 29% -39.5% 136827 +- 32% sched_debug.cpu.ttwu_local.max
0.85 -0.0 0.81 perf-stat.branch-miss-rate%
3.675e+10 -4.1% 3.523e+10 perf-stat.branch-misses
4.052e+11 -2.3% 3.958e+11 perf-stat.cache-misses
7.008e+11 -2.5% 6.832e+11 perf-stat.cache-references
15320995 +- 4% -14.3% 13136557 +- 6% perf-stat.context-switches
9.16 +4.8% 9.59 perf-stat.cpi
2.03e+14 +4.6% 2.124e+14 perf-stat.cpu-cycles
44508 -1.7% 43743 perf-stat.cpu-migrations
1.30 -0.1 1.24 perf-stat.dTLB-store-miss-rate%
4.064e+10 -3.5% 3.922e+10 perf-stat.dTLB-store-misses
3.086e+12 +1.1% 3.119e+12 perf-stat.dTLB-stores
3.611e+08 +- 6% -8.5% 3.304e+08 +- 5% perf-stat.iTLB-loads
0.11 -4.6% 0.10 perf-stat.ipc
4.783e+09 -2.0% 4.685e+09 perf-stat.minor-faults
1.53 +- 2% -0.3 1.22 +- 8% perf-stat.node-load-miss-rate%
1.389e+09 +- 3% -22.1% 1.083e+09 +- 9% perf-stat.node-load-misses
8.922e+10 -1.9% 8.75e+10 perf-stat.node-loads
5.06 +1.7 6.77 +- 3% perf-stat.node-store-miss-rate%
1.204e+09 +29.3% 1.556e+09 +- 3% perf-stat.node-store-misses
2.256e+10 -5.1% 2.142e+10 +- 2% perf-stat.node-stores
4.783e+09 -2.0% 4.685e+09 perf-stat.page-faults
1399242 +1.9% 1425404 perf-stat.path-length
1144 +- 8% -13.6% 988.00 +- 8% slabinfo.Acpi-ParseExt.active_objs
1144 +- 8% -13.6% 988.00 +- 8% slabinfo.Acpi-ParseExt.num_objs
1878 +- 17% +29.0% 2422 +- 16% slabinfo.dmaengine-unmap-16.active_objs
1878 +- 17% +29.0% 2422 +- 16% slabinfo.dmaengine-unmap-16.num_objs
1085 +- 5% -24.1% 823.33 +- 9% slabinfo.file_lock_cache.active_objs
1085 +- 5% -24.1% 823.33 +- 9% slabinfo.file_lock_cache.num_objs
61584 +- 4% -16.6% 51381 +- 5% slabinfo.filp.active_objs
967.00 +- 4% -16.5% 807.67 +- 5% slabinfo.filp.active_slabs
61908 +- 4% -16.5% 51713 +- 5% slabinfo.filp.num_objs
967.00 +- 4% -16.5% 807.67 +- 5% slabinfo.filp.num_slabs
1455 -15.4% 1232 +- 4% slabinfo.nsproxy.active_objs
1455 -15.4% 1232 +- 4% slabinfo.nsproxy.num_objs
84720 +- 6% -18.3% 69210 +- 4% slabinfo.pid.active_objs
1324 +- 6% -18.2% 1083 +- 4% slabinfo.pid.active_slabs
84820 +- 5% -18.2% 69386 +- 4% slabinfo.pid.num_objs
1324 +- 6% -18.2% 1083 +- 4% slabinfo.pid.num_slabs
2112 +- 18% -26.3% 1557 +- 5% slabinfo.scsi_sense_cache.active_objs
2112 +- 18% -26.3% 1557 +- 5% slabinfo.scsi_sense_cache.num_objs
5018 +- 5% -7.6% 4635 +- 4% slabinfo.sock_inode_cache.active_objs
5018 +- 5% -7.6% 4635 +- 4% slabinfo.sock_inode_cache.num_objs
1193 +- 4% +13.8% 1358 +- 4% slabinfo.task_group.active_objs
1193 +- 4% +13.8% 1358 +- 4% slabinfo.task_group.num_objs
62807 +- 3% -14.4% 53757 +- 3% slabinfo.vm_area_struct.active_objs
1571 +- 3% -12.1% 1381 +- 3% slabinfo.vm_area_struct.active_slabs
62877 +- 3% -14.3% 53880 +- 3% slabinfo.vm_area_struct.num_objs
1571 +- 3% -12.1% 1381 +- 3% slabinfo.vm_area_struct.num_slabs
47.45 -47.4 0.00 perf-profile.calltrace.cycles-pp.alloc_pages_vma.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
47.16 -47.2 0.00 perf-profile.calltrace.cycles-pp.__alloc_pages_nodemask.alloc_pages_vma.__handle_mm_fault.handle_mm_fault.__do_page_fault
46.99 -47.0 0.00 perf-profile.calltrace.cycles-pp.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.__handle_mm_fault.handle_mm_fault
44.95 -44.9 0.00 perf-profile.calltrace.cycles-pp._raw_spin_lock.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.__handle_mm_fault
7.42 +- 2% -7.4 0.00 perf-profile.calltrace.cycles-pp.copy_page.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
6.32 +- 10% -6.3 0.00 perf-profile.calltrace.cycles-pp.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
6.28 +- 10% -6.3 0.00 perf-profile.calltrace.cycles-pp.alloc_set_pte.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +0.9 0.85 +- 11% perf-profile.calltrace.cycles-pp._raw_spin_lock.pte_map_lock.alloc_set_pte.finish_fault.handle_pte_fault
0.00 +0.9 0.92 +- 4% perf-profile.calltrace.cycles-pp.__list_del_entry_valid.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault
0.00 +1.1 1.13 +- 7% perf-profile.calltrace.cycles-pp.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault.handle_pte_fault
0.00 +1.2 1.19 +- 7% perf-profile.calltrace.cycles-pp.shmem_getpage_gfp.shmem_fault.__do_fault.handle_pte_fault.__handle_mm_fault
0.00 +1.2 1.22 +- 5% perf-profile.calltrace.cycles-pp.pte_map_lock.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault
0.00 +1.3 1.34 +- 7% perf-profile.calltrace.cycles-pp.shmem_fault.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +1.4 1.36 +- 7% perf-profile.calltrace.cycles-pp.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +4.5 4.54 +- 19% perf-profile.calltrace.cycles-pp.pagevec_lru_move_fn.__lru_cache_add.alloc_set_pte.finish_fault.handle_pte_fault
0.00 +4.6 4.64 +- 19% perf-profile.calltrace.cycles-pp.__lru_cache_add.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault
0.00 +6.6 6.64 +- 15% perf-profile.calltrace.cycles-pp.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +6.7 6.68 +- 15% perf-profile.calltrace.cycles-pp.finish_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +7.5 7.54 +- 5% perf-profile.calltrace.cycles-pp.copy_page.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +44.6 44.55 +- 3% perf-profile.calltrace.cycles-pp._raw_spin_lock.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault
0.00 +46.6 46.63 +- 3% perf-profile.calltrace.cycles-pp.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault.__handle_mm_fault
0.00 +46.8 46.81 +- 3% perf-profile.calltrace.cycles-pp.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +47.1 47.10 +- 3% perf-profile.calltrace.cycles-pp.alloc_pages_vma.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +63.1 63.15 perf-profile.calltrace.cycles-pp.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
0.39 +- 3% +0.0 0.42 +- 3% perf-profile.children.cycles-pp.radix_tree_lookup_slot
0.21 +- 3% +0.0 0.25 +- 5% perf-profile.children.cycles-pp.__mod_node_page_state
0.00 +0.1 0.06 +- 8% perf-profile.children.cycles-pp.get_vma_policy
0.00 +0.1 0.08 +- 5% perf-profile.children.cycles-pp.__lru_cache_add_active_or_unevictable
0.00 +0.2 0.18 +- 6% perf-profile.children.cycles-pp.__page_add_new_anon_rmap
0.00 +1.4 1.35 +- 5% perf-profile.children.cycles-pp.pte_map_lock
0.00 +63.2 63.21 perf-profile.children.cycles-pp.handle_pte_fault
1.40 +- 2% -0.4 1.03 +- 10% perf-profile.self.cycles-pp._raw_spin_lock
0.56 +- 3% -0.2 0.35 +- 6% perf-profile.self.cycles-pp.__handle_mm_fault
0.22 +- 3% -0.0 0.18 +- 7% perf-profile.self.cycles-pp.alloc_set_pte
0.09 +0.0 0.10 +- 4% perf-profile.self.cycles-pp.vmacache_find
0.39 +- 2% +0.0 0.41 +- 3% perf-profile.self.cycles-pp.__radix_tree_lookup
0.18 +0.0 0.20 +- 6% perf-profile.self.cycles-pp.mem_cgroup_charge_statistics
0.17 +- 2% +0.0 0.20 +- 7% perf-profile.self.cycles-pp.___might_sleep
0.33 +- 2% +0.0 0.36 +- 6% perf-profile.self.cycles-pp.handle_mm_fault
0.20 +- 2% +0.0 0.24 +- 3% perf-profile.self.cycles-pp.__mod_node_page_state
0.00 +0.1 0.05 perf-profile.self.cycles-pp.finish_fault
0.00 +0.1 0.05 perf-profile.self.cycles-pp.get_vma_policy
0.00 +0.1 0.08 +- 10% perf-profile.self.cycles-pp.__lru_cache_add_active_or_unevictable
0.00 +0.2 0.25 +- 5% perf-profile.self.cycles-pp.handle_pte_fault
0.00 +0.5 0.49 +- 8% perf-profile.self.cycles-pp.pte_map_lock
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/nr_task/thp_enabled/test/cpufreq_governor:
lkp-skl-4sp1/will-it-scale/debian-x86_64-2018-04-03.cgz/x86_64-rhel-7.2/gcc-7/100%/never/page_fault2/performance
commit:
ba98a1cdad71d259a194461b3a61471b49b14df1
a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
ba98a1cdad71d259 a7a8993bfe3ccb54ad468b9f17
---------------- --------------------------
fail:runs %reproduction fail:runs
| | |
1:3 -33% :3 kmsg.DHCP/BOOTP:Reply_not_for_us_on_eth#,op[#]xid[#]
:3 33% 1:3 dmesg.WARNING:stack_going_in_the_wrong_direction?ip=sched_slice/0x
1:3 -33% :3 dmesg.WARNING:stack_going_in_the_wrong_direction?ip=schedule_tail/0x
1:3 24% 2:3 perf-profile.calltrace.cycles-pp.sync_regs.error_entry
3:3 46% 5:3 perf-profile.calltrace.cycles-pp.error_entry
5:3 -9% 5:3 perf-profile.children.cycles-pp.error_entry
2:3 -4% 2:3 perf-profile.self.cycles-pp.error_entry
%stddev %change %stddev
\ | \
8147 -18.8% 6613 will-it-scale.per_thread_ops
93113 +17.0% 108982 will-it-scale.time.involuntary_context_switches
4.732e+08 -19.0% 3.833e+08 will-it-scale.time.minor_page_faults
5854 +12.0% 6555 will-it-scale.time.percent_of_cpu_this_job_got
35247 +12.1% 39495 will-it-scale.time.system_time
5546661 -15.5% 4689314 will-it-scale.time.voluntary_context_switches
15801637 -1.9% 15504487 will-it-scale.workload
1.43 +- 11% -59.7% 0.58 +- 28% irq_exception_noise.__do_page_fault.min
2811 +- 3% +23.7% 3477 +- 3% kthread_noise.total_time
292776 +- 5% +39.6% 408829 +- 21% meminfo.DirectMap4k
19.80 -3.7 16.12 mpstat.cpu.idle%
29940 -14.5% 25593 uptime.idle
24064 +- 3% -8.5% 22016 vmstat.system.cs
34.86 -1.9% 34.19 boot-time.boot
26.95 -2.8% 26.19 +- 2% boot-time.kernel_boot
7190569 +- 2% -15.2% 6100136 +- 3% softirqs.RCU
5513663 -13.8% 4751548 softirqs.SCHED
18064 +- 2% +24.3% 22461 +- 7% numa-vmstat.node0.nr_slab_unreclaimable
8507 +- 12% -16.8% 7075 +- 4% numa-vmstat.node2.nr_slab_reclaimable
18719 +- 9% -19.6% 15043 +- 4% numa-vmstat.node3.nr_slab_unreclaimable
72265 +- 2% +24.3% 89855 +- 7% numa-meminfo.node0.SUnreclaim
115980 +- 4% +22.6% 142233 +- 12% numa-meminfo.node0.Slab
34035 +- 12% -16.8% 28307 +- 4% numa-meminfo.node2.SReclaimable
74888 +- 9% -19.7% 60162 +- 4% numa-meminfo.node3.SUnreclaim
93113 +17.0% 108982 time.involuntary_context_switches
4.732e+08 -19.0% 3.833e+08 time.minor_page_faults
5854 +12.0% 6555 time.percent_of_cpu_this_job_got
35247 +12.1% 39495 time.system_time
5546661 -15.5% 4689314 time.voluntary_context_switches
4.792e+09 -1.9% 4.699e+09 proc-vmstat.numa_hit
4.791e+09 -1.9% 4.699e+09 proc-vmstat.numa_local
40447 +- 11% +13.2% 45804 +- 6% proc-vmstat.pgactivate
4.778e+09 -1.9% 4.688e+09 proc-vmstat.pgalloc_normal
4.767e+09 -1.9% 4.675e+09 proc-vmstat.pgfault
4.791e+09 -1.9% 4.699e+09 proc-vmstat.pgfree
230178 +- 2% -10.1% 206883 +- 3% cpuidle.C1.usage
1.617e+09 -15.0% 1.375e+09 cpuidle.C1E.time
4514401 -14.1% 3878206 cpuidle.C1E.usage
2.087e+10 -18.5% 1.701e+10 cpuidle.C6.time
24458365 -18.0% 20045336 cpuidle.C6.usage
1163758 -16.1% 976094 +- 4% cpuidle.POLL.time
17907 -14.6% 15294 +- 4% cpuidle.POLL.usage
1758 +4.5% 1838 turbostat.Avg_MHz
227522 +- 2% -10.2% 204426 +- 3% turbostat.C1
4512700 -14.2% 3873264 turbostat.C1E
1.39 -0.2 1.18 turbostat.C1E%
24452583 -18.0% 20039031 turbostat.C6
17.85 -3.3 14.55 turbostat.C6%
7.44 -16.8% 6.19 turbostat.CPU%c1
11.72 -19.3% 9.45 turbostat.CPU%c6
7.51 -21.3% 5.91 turbostat.Pkg%pc2
389.33 +1.6% 395.59 turbostat.PkgWatt
559.33 +- 13% -17.9% 459.33 +- 20% slabinfo.dmaengine-unmap-128.active_objs
559.33 +- 13% -17.9% 459.33 +- 20% slabinfo.dmaengine-unmap-128.num_objs
57734 +- 3% -5.7% 54421 +- 4% slabinfo.filp.active_objs
905.67 +- 3% -5.6% 854.67 +- 4% slabinfo.filp.active_slabs
57981 +- 3% -5.6% 54720 +- 4% slabinfo.filp.num_objs
905.67 +- 3% -5.6% 854.67 +- 4% slabinfo.filp.num_slabs
1378 -12.0% 1212 +- 7% slabinfo.nsproxy.active_objs
1378 -12.0% 1212 +- 7% slabinfo.nsproxy.num_objs
507.33 +- 7% -26.8% 371.33 +- 2% slabinfo.secpath_cache.active_objs
507.33 +- 7% -26.8% 371.33 +- 2% slabinfo.secpath_cache.num_objs
4788 +- 5% -8.3% 4391 +- 2% slabinfo.sock_inode_cache.active_objs
4788 +- 5% -8.3% 4391 +- 2% slabinfo.sock_inode_cache.num_objs
1431 +- 8% -12.3% 1255 +- 3% slabinfo.task_group.active_objs
1431 +- 8% -12.3% 1255 +- 3% slabinfo.task_group.num_objs
4.27 +- 17% +27.0% 5.42 +- 7% sched_debug.cfs_rq:/.runnable_load_avg.avg
13.44 +- 62% +73.6% 23.33 +- 24% sched_debug.cfs_rq:/.runnable_load_avg.stddev
772.55 +- 21% -32.7% 520.27 +- 4% sched_debug.cfs_rq:/.util_est_enqueued.max
4.39 +- 15% +29.0% 5.66 +- 11% sched_debug.cpu.cpu_load[0].avg
152.09 +- 72% +83.9% 279.67 +- 33% sched_debug.cpu.cpu_load[0].max
13.84 +- 58% +78.7% 24.72 +- 29% sched_debug.cpu.cpu_load[0].stddev
4.53 +- 14% +25.8% 5.70 +- 10% sched_debug.cpu.cpu_load[1].avg
156.58 +- 66% +76.6% 276.58 +- 33% sched_debug.cpu.cpu_load[1].max
14.02 +- 55% +72.4% 24.17 +- 28% sched_debug.cpu.cpu_load[1].stddev
4.87 +- 11% +17.3% 5.72 +- 9% sched_debug.cpu.cpu_load[2].avg
1.58 +- 2% +13.5% 1.79 +- 6% sched_debug.cpu.nr_running.max
16694 -14.6% 14259 sched_debug.cpu.nr_switches.min
31989 +- 13% +20.6% 38584 +- 6% sched_debug.cpu.nr_switches.stddev
16505 -14.8% 14068 sched_debug.cpu.sched_count.min
32084 +- 13% +19.9% 38482 +- 6% sched_debug.cpu.sched_count.stddev
8185 -15.0% 6957 sched_debug.cpu.sched_goidle.avg
12151 +- 2% -13.5% 10507 sched_debug.cpu.sched_goidle.max
7867 -15.7% 6631 sched_debug.cpu.sched_goidle.min
7595 -16.1% 6375 sched_debug.cpu.ttwu_count.min
15873 +- 13% +21.2% 19239 +- 6% sched_debug.cpu.ttwu_count.stddev
5244 +- 17% +17.0% 6134 +- 5% sched_debug.cpu.ttwu_local.avg
15646 +- 12% +21.5% 19008 +- 6% sched_debug.cpu.ttwu_local.stddev
0.85 -0.0 0.81 perf-stat.branch-miss-rate%
3.689e+10 -4.6% 3.518e+10 perf-stat.branch-misses
57.39 +0.6 58.00 perf-stat.cache-miss-rate%
4.014e+11 -1.2% 3.967e+11 perf-stat.cache-misses
6.994e+11 -2.2% 6.84e+11 perf-stat.cache-references
14605393 +- 3% -8.5% 13369913 perf-stat.context-switches
9.21 +4.5% 9.63 perf-stat.cpi
2.037e+14 +4.6% 2.13e+14 perf-stat.cpu-cycles
44424 -2.0% 43541 perf-stat.cpu-migrations
1.29 -0.1 1.24 perf-stat.dTLB-store-miss-rate%
4.018e+10 -2.8% 3.905e+10 perf-stat.dTLB-store-misses
3.071e+12 +1.4% 3.113e+12 perf-stat.dTLB-stores
93.04 +1.5 94.51 perf-stat.iTLB-load-miss-rate%
4.946e+09 +19.3% 5.903e+09 +- 5% perf-stat.iTLB-load-misses
3.702e+08 -7.5% 3.423e+08 +- 2% perf-stat.iTLB-loads
4470 -15.9% 3760 +- 5% perf-stat.instructions-per-iTLB-miss
0.11 -4.3% 0.10 perf-stat.ipc
4.767e+09 -1.9% 4.675e+09 perf-stat.minor-faults
1.46 +- 4% -0.1 1.33 +- 9% perf-stat.node-load-miss-rate%
4.91 +1.7 6.65 +- 2% perf-stat.node-store-miss-rate%
1.195e+09 +32.8% 1.587e+09 +- 2% perf-stat.node-store-misses
2.313e+10 -3.7% 2.227e+10 perf-stat.node-stores
4.767e+09 -1.9% 4.675e+09 perf-stat.page-faults
1399047 +2.0% 1427115 perf-stat.path-length
8908 +- 73% -100.0% 0.00 latency_stats.avg.call_rwsem_down_read_failed.m_start.seq_read.__vfs_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
3604 +-141% -100.0% 0.00 latency_stats.avg.call_rwsem_down_write_failed.do_unlinkat.do_syscall_64.entry_SYSCALL_64_after_hwframe
61499 +-130% -92.6% 4534 +- 16% latency_stats.avg.expand_files.__alloc_fd.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
4391 +-138% -70.9% 1277 +-129% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup_revalidate.lookup_fast.walk_component.link_path_walk.path_lookupat.filename_lookup
67311 +-112% -48.5% 34681 +- 36% latency_stats.avg.max
3956 +-138% +320.4% 16635 +-140% latency_stats.avg.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
164.67 +- 30% +7264.0% 12126 +-138% latency_stats.avg.flush_work.fsnotify_destroy_group.inotify_release.__fput.task_work_run.exit_to_usermode_loop.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +5.4e+105% 5367 +-141% latency_stats.avg.call_rwsem_down_write_failed.unlink_file_vma.free_pgtables.exit_mmap.mmput.flush_old_exec.load_elf_binary.search_binary_handler.do_execveat_common.__x64_sys_execve.do_syscall_64.entry_SYSCALL_64_after_hwframe
36937 +-119% -100.0% 0.00 latency_stats.max.call_rwsem_down_read_failed.m_start.seq_read.__vfs_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
3604 +-141% -100.0% 0.00 latency_stats.max.call_rwsem_down_write_failed.do_unlinkat.do_syscall_64.entry_SYSCALL_64_after_hwframe
84146 +-107% -72.5% 23171 +- 31% latency_stats.max.expand_files.__alloc_fd.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
4391 +-138% -70.9% 1277 +-129% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup_revalidate.lookup_fast.walk_component.link_path_walk.path_lookupat.filename_lookup
5817 +- 83% -69.7% 1760 +- 67% latency_stats.max.pipe_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
6720 +-137% +1628.2% 116147 +-141% latency_stats.max.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
164.67 +- 30% +7264.0% 12126 +-138% latency_stats.max.flush_work.fsnotify_destroy_group.inotify_release.__fput.task_work_run.exit_to_usermode_loop.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +1.2e+106% 12153 +-141% latency_stats.max.call_rwsem_down_write_failed.unlink_file_vma.free_pgtables.exit_mmap.mmput.flush_old_exec.load_elf_binary.search_binary_handler.do_execveat_common.__x64_sys_execve.do_syscall_64.entry_SYSCALL_64_after_hwframe
110122 +-120% -100.0% 0.00 latency_stats.sum.call_rwsem_down_read_failed.m_start.seq_read.__vfs_read.vfs_read.ksys_read.do_syscall_64.entry_SYSCALL_64_after_hwframe
3604 +-141% -100.0% 0.00 latency_stats.sum.call_rwsem_down_write_failed.do_unlinkat.do_syscall_64.entry_SYSCALL_64_after_hwframe
12078828 +-139% -99.3% 89363 +- 29% latency_stats.sum.expand_files.__alloc_fd.do_sys_open.do_syscall_64.entry_SYSCALL_64_after_hwframe
144453 +-120% -80.9% 27650 +- 19% latency_stats.sum.poll_schedule_timeout.do_sys_poll.__x64_sys_poll.do_syscall_64.entry_SYSCALL_64_after_hwframe
4391 +-138% -70.9% 1277 +-129% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_lookup.nfs_lookup_revalidate.lookup_fast.walk_component.link_path_walk.path_lookupat.filename_lookup
9438 +- 86% -68.4% 2980 +- 35% latency_stats.sum.pipe_write.__vfs_write.vfs_write.ksys_write.do_syscall_64.entry_SYSCALL_64_after_hwframe
31656 +-138% +320.4% 133084 +-140% latency_stats.sum.rpc_wait_bit_killable.__rpc_execute.rpc_run_task.rpc_call_sync.nfs3_rpc_wrapper.nfs3_proc_getattr.__nfs_revalidate_inode.nfs_do_access.nfs_permission.inode_permission.link_path_walk.path_lookupat
164.67 +- 30% +7264.0% 12126 +-138% latency_stats.sum.flush_work.fsnotify_destroy_group.inotify_release.__fput.task_work_run.exit_to_usermode_loop.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +8.8e+105% 8760 +-141% latency_stats.sum.msleep_interruptible.uart_wait_until_sent.tty_wait_until_sent.tty_port_close_start.tty_port_close.tty_release.__fput.task_work_run.exit_to_usermode_loop.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +1.3e+106% 12897 +-141% latency_stats.sum.tty_wait_until_sent.tty_port_close_start.tty_port_close.tty_release.__fput.task_work_run.exit_to_usermode_loop.do_syscall_64.entry_SYSCALL_64_after_hwframe
0.00 +3.2e+106% 32207 +-141% latency_stats.sum.call_rwsem_down_write_failed.unlink_file_vma.free_pgtables.exit_mmap.mmput.flush_old_exec.load_elf_binary.search_binary_handler.do_execveat_common.__x64_sys_execve.do_syscall_64.entry_SYSCALL_64_after_hwframe
44.43 +- 3% -44.4 0.00 perf-profile.calltrace.cycles-pp.alloc_pages_vma.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
44.13 +- 3% -44.1 0.00 perf-profile.calltrace.cycles-pp.__alloc_pages_nodemask.alloc_pages_vma.__handle_mm_fault.handle_mm_fault.__do_page_fault
43.95 +- 3% -43.9 0.00 perf-profile.calltrace.cycles-pp.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.__handle_mm_fault.handle_mm_fault
41.85 +- 4% -41.9 0.00 perf-profile.calltrace.cycles-pp._raw_spin_lock.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.__handle_mm_fault
7.74 +- 8% -7.7 0.00 perf-profile.calltrace.cycles-pp.copy_page.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
7.19 +- 4% -7.2 0.00 perf-profile.calltrace.cycles-pp.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
7.15 +- 4% -7.2 0.00 perf-profile.calltrace.cycles-pp.alloc_set_pte.finish_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
5.09 +- 3% -5.1 0.00 perf-profile.calltrace.cycles-pp.__lru_cache_add.alloc_set_pte.finish_fault.__handle_mm_fault.handle_mm_fault
4.99 +- 3% -5.0 0.00 perf-profile.calltrace.cycles-pp.pagevec_lru_move_fn.__lru_cache_add.alloc_set_pte.finish_fault.__handle_mm_fault
0.93 +- 6% -0.1 0.81 +- 2% perf-profile.calltrace.cycles-pp.find_get_entry.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault
0.00 +0.8 0.84 perf-profile.calltrace.cycles-pp._raw_spin_lock.pte_map_lock.alloc_set_pte.finish_fault.handle_pte_fault
0.00 +0.9 0.92 +- 3% perf-profile.calltrace.cycles-pp.__list_del_entry_valid.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault
0.00 +1.1 1.08 perf-profile.calltrace.cycles-pp.find_lock_entry.shmem_getpage_gfp.shmem_fault.__do_fault.handle_pte_fault
0.00 +1.1 1.14 perf-profile.calltrace.cycles-pp.shmem_getpage_gfp.shmem_fault.__do_fault.handle_pte_fault.__handle_mm_fault
0.00 +1.2 1.17 perf-profile.calltrace.cycles-pp.pte_map_lock.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault
0.00 +1.3 1.29 perf-profile.calltrace.cycles-pp.shmem_fault.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +1.3 1.31 perf-profile.calltrace.cycles-pp.__do_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
61.62 +1.7 63.33 perf-profile.calltrace.cycles-pp.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault.page_fault
41.73 +- 4% +3.0 44.75 perf-profile.calltrace.cycles-pp.native_queued_spin_lock_slowpath._raw_spin_lock.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma
0.00 +4.6 4.55 +- 15% perf-profile.calltrace.cycles-pp.pagevec_lru_move_fn.__lru_cache_add.alloc_set_pte.finish_fault.handle_pte_fault
0.00 +4.6 4.65 +- 14% perf-profile.calltrace.cycles-pp.__lru_cache_add.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault
0.00 +6.6 6.57 +- 10% perf-profile.calltrace.cycles-pp.alloc_set_pte.finish_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +6.6 6.61 +- 10% perf-profile.calltrace.cycles-pp.finish_fault.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +7.2 7.25 +- 2% perf-profile.calltrace.cycles-pp.copy_page.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
41.41 +- 70% +22.3 63.67 perf-profile.calltrace.cycles-pp.handle_mm_fault.__do_page_fault.do_page_fault.page_fault
42.19 +- 70% +22.6 64.75 perf-profile.calltrace.cycles-pp.__do_page_fault.do_page_fault.page_fault
42.20 +- 70% +22.6 64.76 perf-profile.calltrace.cycles-pp.do_page_fault.page_fault
42.27 +- 70% +22.6 64.86 perf-profile.calltrace.cycles-pp.page_fault
0.00 +44.9 44.88 perf-profile.calltrace.cycles-pp._raw_spin_lock.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault
0.00 +46.9 46.92 perf-profile.calltrace.cycles-pp.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault.__handle_mm_fault
0.00 +47.1 47.10 perf-profile.calltrace.cycles-pp.__alloc_pages_nodemask.alloc_pages_vma.handle_pte_fault.__handle_mm_fault.handle_mm_fault
0.00 +47.4 47.37 perf-profile.calltrace.cycles-pp.alloc_pages_vma.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault
0.00 +63.0 63.00 perf-profile.calltrace.cycles-pp.handle_pte_fault.__handle_mm_fault.handle_mm_fault.__do_page_fault.do_page_fault
0.97 +- 6% -0.1 0.84 +- 2% perf-profile.children.cycles-pp.find_get_entry
1.23 +- 6% -0.1 1.11 perf-profile.children.cycles-pp.find_lock_entry
0.09 +- 10% -0.0 0.07 +- 6% perf-profile.children.cycles-pp.unlock_page
0.19 +- 4% +0.0 0.21 +- 2% perf-profile.children.cycles-pp.mem_cgroup_charge_statistics
0.21 +- 2% +0.0 0.25 perf-profile.children.cycles-pp.__mod_node_page_state
0.00 +0.1 0.05 +- 8% perf-profile.children.cycles-pp.get_vma_policy
0.00 +0.1 0.08 perf-profile.children.cycles-pp.__lru_cache_add_active_or_unevictable
0.00 +0.2 0.18 +- 2% perf-profile.children.cycles-pp.__page_add_new_anon_rmap
0.00 +1.3 1.30 perf-profile.children.cycles-pp.pte_map_lock
63.40 +1.6 64.97 perf-profile.children.cycles-pp.__do_page_fault
63.19 +1.6 64.83 perf-profile.children.cycles-pp.do_page_fault
61.69 +1.7 63.36 perf-profile.children.cycles-pp.__handle_mm_fault
63.19 +1.7 64.86 perf-profile.children.cycles-pp.page_fault
61.99 +1.7 63.70 perf-profile.children.cycles-pp.handle_mm_fault
72.27 +2.2 74.52 perf-profile.children.cycles-pp.native_queued_spin_lock_slowpath
67.51 +2.4 69.87 perf-profile.children.cycles-pp._raw_spin_lock
44.49 +- 3% +3.0 47.45 perf-profile.children.cycles-pp.alloc_pages_vma
44.28 +- 3% +3.0 47.26 perf-profile.children.cycles-pp.__alloc_pages_nodemask
44.13 +- 3% +3.0 47.12 perf-profile.children.cycles-pp.get_page_from_freelist
0.00 +63.1 63.06 perf-profile.children.cycles-pp.handle_pte_fault
1.46 +- 7% -0.5 1.01 perf-profile.self.cycles-pp._raw_spin_lock
0.58 +- 6% -0.2 0.34 perf-profile.self.cycles-pp.__handle_mm_fault
0.55 +- 6% -0.1 0.44 +- 2% perf-profile.self.cycles-pp.find_get_entry
0.22 +- 5% -0.1 0.16 +- 2% perf-profile.self.cycles-pp.alloc_set_pte
0.10 +- 8% -0.0 0.08 perf-profile.self.cycles-pp.down_read_trylock
0.09 +- 5% -0.0 0.07 perf-profile.self.cycles-pp.unlock_page
0.06 -0.0 0.05 perf-profile.self.cycles-pp.pmd_devmap_trans_unstable
0.20 +- 2% +0.0 0.24 +- 3% perf-profile.self.cycles-pp.__mod_node_page_state
0.00 +0.1 0.05 perf-profile.self.cycles-pp.finish_fault
0.00 +0.1 0.05 perf-profile.self.cycles-pp.get_vma_policy
0.00 +0.1 0.08 +- 6% perf-profile.self.cycles-pp.__lru_cache_add_active_or_unevictable
0.00 +0.2 0.25 perf-profile.self.cycles-pp.handle_pte_fault
0.00 +0.5 0.46 +- 7% perf-profile.self.cycles-pp.pte_map_lock
72.26 +2.3 74.52 perf-profile.self.cycles-pp.native_queued_spin_lock_slowpath
[-- Attachment #3: perf-profile.zip --]
[-- Type: application/zip, Size: 19025 bytes --]
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-06-11 7:49 ` Song, HaiyanX
@ 2018-06-11 15:15 ` Laurent Dufour
2018-06-19 9:16 ` Haiyan Song
2018-07-02 8:59 ` Laurent Dufour
1 sibling, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2018-06-11 15:15 UTC (permalink / raw)
To: Song, HaiyanX
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
Hi Haiyan,
I don't have access to the same hardware you ran the test on, but I give a try
to those test on a Power8 system (2 sockets, 5 cores/s, 8 threads/c, 80 CPUs 32G).
I run each will-it-scale test 10 times and compute the average.
test THP enabled 4.17.0-rc4-mm1 spf delta
page_fault3_threads 2697.7 2683.5 -0.53%
page_fault2_threads 170660.6 169574.1 -0.64%
context_switch1_threads 6915269.2 6877507.3 -0.55%
context_switch1_processes 6478076.2 6529493.5 0.79%
brk1 243391.2 238527.5 -2.00%
Test were launched with the arguments '-t 80 -s 5', only the average report is
taken in account. Note that page size is 64K by default on ppc64.
It would be nice if you could capture some perf data to figure out why the
page_fault2/3 are showing such a performance regression.
Thanks,
Laurent.
On 11/06/2018 09:49, Song, HaiyanX wrote:
> Hi Laurent,
>
> Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
> tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
> V9 patch serials.
>
> The regression result is sorted by the metric will-it-scale.per_thread_ops.
> branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
> commit id:
> head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
> base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
> Benchmark: will-it-scale
> Download link: https://github.com/antonblanchard/will-it-scale/tree/master
>
> Metrics:
> will-it-scale.per_process_ops=processes/nr_cpu
> will-it-scale.per_thread_ops=threads/nr_cpu
> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
> THP: enable / disable
> nr_task:100%
>
> 1. Regressions:
>
> a). Enable THP
> testcase base change head metric
> page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
> page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
> brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
> context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
> context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
>
> b). Disable THP
> page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
> page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
> brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
> context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
> brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
> page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
> context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
>
> Notes: for the above values of test result, the higher is better.
>
> 2. Improvement: not found improvement based on the selected test cases.
>
>
> Best regards
> Haiyan Song
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Monday, May 28, 2018 4:54 PM
> To: Song, HaiyanX
> Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: Re: [PATCH v11 00/26] Speculative page faults
>
> On 28/05/2018 10:22, Haiyan Song wrote:
>> Hi Laurent,
>>
>> Yes, these tests are done on V9 patch.
>
> Do you plan to give this V11 a run ?
>
>>
>>
>> Best regards,
>> Haiyan Song
>>
>> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>>
>>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>>> tested on Intel 4s Skylake platform.
>>>
>>> Hi,
>>>
>>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>>> series" while responding to the v11 header series...
>>> Were these tests done on v9 or v11 ?
>>>
>>> Cheers,
>>> Laurent.
>>>
>>>>
>>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>>> Commit id:
>>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>>> Benchmark suite: will-it-scale
>>>> Download link:
>>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>>> Metrics:
>>>> will-it-scale.per_process_ops=processes/nr_cpu
>>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>>> THP: enable / disable
>>>> nr_task: 100%
>>>>
>>>> 1. Regressions:
>>>> a) THP enabled:
>>>> testcase base change head metric
>>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>>
>>>> b) THP disabled:
>>>> testcase base change head metric
>>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>>
>>>> 2. Improvements:
>>>> a) THP enabled:
>>>> testcase base change head metric
>>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>>
>>>> b) THP disabled:
>>>> testcase base change head metric
>>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>>
>>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>>> on head commit is better than that on base commit for this benchmark.
>>>>
>>>>
>>>> Best regards
>>>> Haiyan Song
>>>>
>>>> ________________________________________
>>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>>> Sent: Thursday, May 17, 2018 7:06 PM
>>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>>
>>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>>> page fault without holding the mm semaphore [1].
>>>>
>>>> The idea is to try to handle user space page faults without holding the
>>>> mmap_sem. This should allow better concurrency for massively threaded
>>>> process since the page fault handler will not wait for other threads memory
>>>> layout change to be done, assuming that this change is done in another part
>>>> of the process's memory space. This type page fault is named speculative
>>>> page fault. If the speculative page fault fails because of a concurrency is
>>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>>> is failing its processing and a classic page fault is then tried.
>>>>
>>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>>> which protects the access to the mm_rb tree. Previously this was done using
>>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>>> freeing operation which was hitting the performance by 20% as reported by
>>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>>> limiting the locking contention to these operations which are expected to
>>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>>> our back a reference count is added and 2 services (get_vma() and
>>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>>> fetched from the RB tree using get_vma(), it must be later freed using
>>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>>> benchmark anymore.
>>>>
>>>> The VMA's attributes checked during the speculative page fault processing
>>>> have to be protected against parallel changes. This is done by using a per
>>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>>> handler to fast check for parallel changes in progress and to abort the
>>>> speculative page fault in that case.
>>>>
>>>> Once the VMA has been found, the speculative page fault handler would check
>>>> for the VMA's attributes to verify that the page fault has to be handled
>>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>>> allows fast detection of concurrent VMA changes. If such a change is
>>>> detected, the speculative page fault is aborted and a *classic* page fault
>>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>>> checked during the page fault are modified.
>>>>
>>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>>> so once the page table is locked, the VMA is valid, so any other changes
>>>> leading to touching this PTE will need to lock the page table, so no
>>>> parallel change is possible at this time.
>>>>
>>>> The locking of the PTE is done with interrupts disabled, this allows
>>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>>> valid at the time the PTE is locked, we have the guarantee that the
>>>> collapsing operation will have to wait on the PTE lock to move forward.
>>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>>> different from the one recorded at the beginning of the SPF operation, the
>>>> classic page fault handler will be called to handle the operation while
>>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>>> page fault while a TLB invalidate is requested by another CPU holding the
>>>> PTE.
>>>>
>>>> In pseudo code, this could be seen as:
>>>> speculative_page_fault()
>>>> {
>>>> vma = get_vma()
>>>> check vma sequence count
>>>> check vma's support
>>>> disable interrupt
>>>> check pgd,p4d,...,pte
>>>> save pmd and pte in vmf
>>>> save vma sequence counter in vmf
>>>> enable interrupt
>>>> check vma sequence count
>>>> handle_pte_fault(vma)
>>>> ..
>>>> page = alloc_page()
>>>> pte_map_lock()
>>>> disable interrupt
>>>> abort if sequence counter has changed
>>>> abort if pmd or pte has changed
>>>> pte map and lock
>>>> enable interrupt
>>>> if abort
>>>> free page
>>>> abort
>>>> ...
>>>> }
>>>>
>>>> arch_fault_handler()
>>>> {
>>>> if (speculative_page_fault(&vma))
>>>> goto done
>>>> again:
>>>> lock(mmap_sem)
>>>> vma = find_vma();
>>>> handle_pte_fault(vma);
>>>> if retry
>>>> unlock(mmap_sem)
>>>> goto again;
>>>> done:
>>>> handle fault error
>>>> }
>>>>
>>>> Support for THP is not done because when checking for the PMD, we can be
>>>> confused by an in progress collapsing operation done by khugepaged. The
>>>> issue is that pmd_none() could be true either if the PMD is not already
>>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>>> cannot safely allocate a PMD if pmd_none() is true.
>>>>
>>>> This series add a new software performance event named 'speculative-faults'
>>>> or 'spf'. It counts the number of successful page fault event handled
>>>> speculatively. When recording 'faults,spf' events, the faults one is
>>>> counting the total number of page fault events while 'spf' is only counting
>>>> the part of the faults processed speculatively.
>>>>
>>>> There are some trace events introduced by this series. They allow
>>>> identifying why the page faults were not processed speculatively. This
>>>> doesn't take in account the faults generated by a monothreaded process
>>>> which directly processed while holding the mmap_sem. This trace events are
>>>> grouped in a system named 'pagefault', they are:
>>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>>> back.
>>>>
>>>> To record all the related events, the easier is to run perf with the
>>>> following arguments :
>>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>>
>>>> There is also a dedicated vmstat counter showing the number of successful
>>>> page fault handled speculatively. I can be seen this way:
>>>> $ grep speculative_pgfault /proc/vmstat
>>>>
>>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>>> on x86, PowerPC and arm64.
>>>>
>>>> ---------------------
>>>> Real Workload results
>>>>
>>>> As mentioned in previous email, we did non official runs using a "popular
>>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>>> which showed a 30% improvements in the number of transaction processed per
>>>> second. This run has been done on the v6 series, but changes introduced in
>>>> this new version should not impact the performance boost seen.
>>>>
>>>> Here are the perf data captured during 2 of these runs on top of the v8
>>>> series:
>>>> vanilla spf
>>>> faults 89.418 101.364 +13%
>>>> spf n/a 97.989
>>>>
>>>> With the SPF kernel, most of the page fault were processed in a speculative
>>>> way.
>>>>
>>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>>> it a try on an android device. He reported that the application launch time
>>>> was improved in average by 6%, and for large applications (~100 threads) by
>>>> 20%.
>>>>
>>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>>> MSM845 (8 cores) with 6GB (the less is better):
>>>>
>>>> Application 4.9 4.9+spf delta
>>>> com.tencent.mm 416 389 -7%
>>>> com.eg.android.AlipayGphone 1135 986 -13%
>>>> com.tencent.mtt 455 454 0%
>>>> com.qqgame.hlddz 1497 1409 -6%
>>>> com.autonavi.minimap 711 701 -1%
>>>> com.tencent.tmgp.sgame 788 748 -5%
>>>> com.immomo.momo 501 487 -3%
>>>> com.tencent.peng 2145 2112 -2%
>>>> com.smile.gifmaker 491 461 -6%
>>>> com.baidu.BaiduMap 479 366 -23%
>>>> com.taobao.taobao 1341 1198 -11%
>>>> com.baidu.searchbox 333 314 -6%
>>>> com.tencent.mobileqq 394 384 -3%
>>>> com.sina.weibo 907 906 0%
>>>> com.youku.phone 816 731 -11%
>>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>>> com.UCMobile 415 411 -1%
>>>> com.tencent.tmgp.ak 1464 1431 -2%
>>>> com.tencent.qqmusic 336 329 -2%
>>>> com.sankuai.meituan 1661 1302 -22%
>>>> com.netease.cloudmusic 1193 1200 1%
>>>> air.tv.douyu.android 4257 4152 -2%
>>>>
>>>> ------------------
>>>> Benchmarks results
>>>>
>>>> Base kernel is v4.17.0-rc4-mm1
>>>> SPF is BASE + this series
>>>>
>>>> Kernbench:
>>>> ----------
>>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>>> kernel (kernel is build 5 times):
>>>>
>>>> Average Half load -j 8
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>>
>>>> Average Optimal load -j 16
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>>
>>>>
>>>> During a run on the SPF, perf events were captured:
>>>> Performance counter stats for '../kernbench -M':
>>>> 526743764 faults
>>>> 210 spf
>>>> 3 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 2278 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> Very few speculative page faults were recorded as most of the processes
>>>> involved are monothreaded (sounds that on this architecture some threads
>>>> were created during the kernel build processing).
>>>>
>>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>>
>>>> Average Half load -j 40
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>>
>>>> Average Optimal load -j 80
>>>> Run (std deviation)
>>>> BASE SPF
>>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>>
>>>> During a run on the SPF, perf events were captured:
>>>> Performance counter stats for '../kernbench -M':
>>>> 116730856 faults
>>>> 0 spf
>>>> 3 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 476 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> Most of the processes involved are monothreaded so SPF is not activated but
>>>> there is no impact on the performance.
>>>>
>>>> Ebizzy:
>>>> -------
>>>> The test is counting the number of records per second it can manage, the
>>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>>> consistent result I repeated the test 100 times and measure the average
>>>> result. The number is the record processes per second, the higher is the
>>>> best.
>>>>
>>>> BASE SPF delta
>>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>>
>>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>>> Performance counter stats for './ebizzy -mTt 16':
>>>> 1706379 faults
>>>> 1674599 spf
>>>> 30588 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 363 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> And the ones captured during a run on a 80 CPUs Power node:
>>>> Performance counter stats for './ebizzy -mTt 80':
>>>> 1874773 faults
>>>> 1461153 spf
>>>> 413293 pagefault:spf_vma_changed
>>>> 0 pagefault:spf_vma_noanon
>>>> 200 pagefault:spf_vma_notsup
>>>> 0 pagefault:spf_vma_access
>>>> 0 pagefault:spf_pmd_changed
>>>>
>>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>>> leading the ebizzy performance boost.
>>>>
>>>> ------------------
>>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>>> and Minchan Kim, hopefully.
>>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>>> __do_page_fault().
>>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>>> instead
>>>> of aborting the speculative page fault handling. Dropping the now
>>>> useless
>>>> trace event pagefault:spf_pte_lock.
>>>> - No more try to reuse the fetched VMA during the speculative page fault
>>>> handling when retrying is needed. This adds a lot of complexity and
>>>> additional tests done didn't show a significant performance improvement.
>>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>>
>>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>>
>>>>
>>>> Laurent Dufour (20):
>>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>>> mm: make pte_unmap_same compatible with SPF
>>>> mm: introduce INIT_VMA()
>>>> mm: protect VMA modifications using VMA sequence count
>>>> mm: protect mremap() against SPF hanlder
>>>> mm: protect SPF handler against anon_vma changes
>>>> mm: cache some VMA fields in the vm_fault structure
>>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>>> mm: introduce __lru_cache_add_active_or_unevictable
>>>> mm: introduce __vm_normal_page()
>>>> mm: introduce __page_add_new_anon_rmap()
>>>> mm: protect mm_rb tree with a rwlock
>>>> mm: adding speculative page fault failure trace events
>>>> perf: add a speculative page fault sw event
>>>> perf tools: add support for the SPF perf event
>>>> mm: add speculative page fault vmstats
>>>> powerpc/mm: add speculative page fault
>>>>
>>>> Mahendran Ganesh (2):
>>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>>> arm64/mm: add speculative page fault
>>>>
>>>> Peter Zijlstra (4):
>>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>>> mm: VMA sequence count
>>>> mm: provide speculative fault infrastructure
>>>> x86/mm: add speculative pagefault handling
>>>>
>>>> arch/arm64/Kconfig | 1 +
>>>> arch/arm64/mm/fault.c | 12 +
>>>> arch/powerpc/Kconfig | 1 +
>>>> arch/powerpc/mm/fault.c | 16 +
>>>> arch/x86/Kconfig | 1 +
>>>> arch/x86/mm/fault.c | 27 +-
>>>> fs/exec.c | 2 +-
>>>> fs/proc/task_mmu.c | 5 +-
>>>> fs/userfaultfd.c | 17 +-
>>>> include/linux/hugetlb_inline.h | 2 +-
>>>> include/linux/migrate.h | 4 +-
>>>> include/linux/mm.h | 136 +++++++-
>>>> include/linux/mm_types.h | 7 +
>>>> include/linux/pagemap.h | 4 +-
>>>> include/linux/rmap.h | 12 +-
>>>> include/linux/swap.h | 10 +-
>>>> include/linux/vm_event_item.h | 3 +
>>>> include/trace/events/pagefault.h | 80 +++++
>>>> include/uapi/linux/perf_event.h | 1 +
>>>> kernel/fork.c | 5 +-
>>>> mm/Kconfig | 22 ++
>>>> mm/huge_memory.c | 6 +-
>>>> mm/hugetlb.c | 2 +
>>>> mm/init-mm.c | 3 +
>>>> mm/internal.h | 20 ++
>>>> mm/khugepaged.c | 5 +
>>>> mm/madvise.c | 6 +-
>>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>>> mm/mempolicy.c | 51 ++-
>>>> mm/migrate.c | 6 +-
>>>> mm/mlock.c | 13 +-
>>>> mm/mmap.c | 229 ++++++++++---
>>>> mm/mprotect.c | 4 +-
>>>> mm/mremap.c | 13 +
>>>> mm/nommu.c | 2 +-
>>>> mm/rmap.c | 5 +-
>>>> mm/swap.c | 6 +-
>>>> mm/swap_state.c | 8 +-
>>>> mm/vmstat.c | 5 +-
>>>> tools/include/uapi/linux/perf_event.h | 1 +
>>>> tools/perf/util/evsel.c | 1 +
>>>> tools/perf/util/parse-events.c | 4 +
>>>> tools/perf/util/parse-events.l | 1 +
>>>> tools/perf/util/python.c | 1 +
>>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>>> create mode 100644 include/trace/events/pagefault.h
>>>>
>>>> --
>>>> 2.7.4
>>>>
>>>>
>>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-05-28 8:54 ` Laurent Dufour
2018-05-28 11:04 ` Wang, Kemi
@ 2018-06-11 7:49 ` Song, HaiyanX
2018-06-11 15:15 ` Laurent Dufour
2018-07-02 8:59 ` Laurent Dufour
1 sibling, 2 replies; 46+ messages in thread
From: Song, HaiyanX @ 2018-06-11 7:49 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
Hi Laurent,
Regression test for v11 patch serials have been run, some regression is found by LKP-tools (linux kernel performance)
tested on Intel 4s skylake platform. This time only test the cases which have been run and found regressions on
V9 patch serials.
The regression result is sorted by the metric will-it-scale.per_thread_ops.
branch: Laurent-Dufour/Speculative-page-faults/20180520-045126
commit id:
head commit : a7a8993bfe3ccb54ad468b9f1799649e4ad1ff12
base commit : ba98a1cdad71d259a194461b3a61471b49b14df1
Benchmark: will-it-scale
Download link: https://github.com/antonblanchard/will-it-scale/tree/master
Metrics:
will-it-scale.per_process_ops=processes/nr_cpu
will-it-scale.per_thread_ops=threads/nr_cpu
test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
THP: enable / disable
nr_task:100%
1. Regressions:
a). Enable THP
testcase base change head metric
page_fault3/enable THP 10519 -20.5% 836 will-it-scale.per_thread_ops
page_fault2/enalbe THP 8281 -18.8% 6728 will-it-scale.per_thread_ops
brk1/eanble THP 998475 -2.2% 976893 will-it-scale.per_process_ops
context_switch1/enable THP 223910 -1.3% 220930 will-it-scale.per_process_ops
context_switch1/enable THP 233722 -1.0% 231288 will-it-scale.per_thread_ops
b). Disable THP
page_fault3/disable THP 10856 -23.1% 8344 will-it-scale.per_thread_ops
page_fault2/disable THP 8147 -18.8% 6613 will-it-scale.per_thread_ops
brk1/disable THP 957 -7.9% 881 will-it-scale.per_thread_ops
context_switch1/disable THP 237006 -2.2% 231907 will-it-scale.per_thread_ops
brk1/disable THP 997317 -2.0% 977778 will-it-scale.per_process_ops
page_fault3/disable THP 467454 -1.8% 459251 will-it-scale.per_process_ops
context_switch1/disable THP 224431 -1.3% 221567 will-it-scale.per_process_ops
Notes: for the above values of test result, the higher is better.
2. Improvement: not found improvement based on the selected test cases.
Best regards
Haiyan Song
________________________________________
From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
Sent: Monday, May 28, 2018 4:54 PM
To: Song, HaiyanX
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: Re: [PATCH v11 00/26] Speculative page faults
On 28/05/2018 10:22, Haiyan Song wrote:
> Hi Laurent,
>
> Yes, these tests are done on V9 patch.
Do you plan to give this V11 a run ?
>
>
> Best regards,
> Haiyan Song
>
> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>
>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>> tested on Intel 4s Skylake platform.
>>
>> Hi,
>>
>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>> series" while responding to the v11 header series...
>> Were these tests done on v9 or v11 ?
>>
>> Cheers,
>> Laurent.
>>
>>>
>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>> Commit id:
>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>> Benchmark suite: will-it-scale
>>> Download link:
>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>> Metrics:
>>> will-it-scale.per_process_ops=processes/nr_cpu
>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>> THP: enable / disable
>>> nr_task: 100%
>>>
>>> 1. Regressions:
>>> a) THP enabled:
>>> testcase base change head metric
>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>
>>> b) THP disabled:
>>> testcase base change head metric
>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>
>>> 2. Improvements:
>>> a) THP enabled:
>>> testcase base change head metric
>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>
>>> b) THP disabled:
>>> testcase base change head metric
>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>
>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>> on head commit is better than that on base commit for this benchmark.
>>>
>>>
>>> Best regards
>>> Haiyan Song
>>>
>>> ________________________________________
>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Thursday, May 17, 2018 7:06 PM
>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>
>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>> page fault without holding the mm semaphore [1].
>>>
>>> The idea is to try to handle user space page faults without holding the
>>> mmap_sem. This should allow better concurrency for massively threaded
>>> process since the page fault handler will not wait for other threads memory
>>> layout change to be done, assuming that this change is done in another part
>>> of the process's memory space. This type page fault is named speculative
>>> page fault. If the speculative page fault fails because of a concurrency is
>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>> is failing its processing and a classic page fault is then tried.
>>>
>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>> which protects the access to the mm_rb tree. Previously this was done using
>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>> freeing operation which was hitting the performance by 20% as reported by
>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>> limiting the locking contention to these operations which are expected to
>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>> our back a reference count is added and 2 services (get_vma() and
>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>> fetched from the RB tree using get_vma(), it must be later freed using
>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>> benchmark anymore.
>>>
>>> The VMA's attributes checked during the speculative page fault processing
>>> have to be protected against parallel changes. This is done by using a per
>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>> handler to fast check for parallel changes in progress and to abort the
>>> speculative page fault in that case.
>>>
>>> Once the VMA has been found, the speculative page fault handler would check
>>> for the VMA's attributes to verify that the page fault has to be handled
>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>> allows fast detection of concurrent VMA changes. If such a change is
>>> detected, the speculative page fault is aborted and a *classic* page fault
>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>> checked during the page fault are modified.
>>>
>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>> so once the page table is locked, the VMA is valid, so any other changes
>>> leading to touching this PTE will need to lock the page table, so no
>>> parallel change is possible at this time.
>>>
>>> The locking of the PTE is done with interrupts disabled, this allows
>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>> valid at the time the PTE is locked, we have the guarantee that the
>>> collapsing operation will have to wait on the PTE lock to move forward.
>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>> different from the one recorded at the beginning of the SPF operation, the
>>> classic page fault handler will be called to handle the operation while
>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>> page fault while a TLB invalidate is requested by another CPU holding the
>>> PTE.
>>>
>>> In pseudo code, this could be seen as:
>>> speculative_page_fault()
>>> {
>>> vma = get_vma()
>>> check vma sequence count
>>> check vma's support
>>> disable interrupt
>>> check pgd,p4d,...,pte
>>> save pmd and pte in vmf
>>> save vma sequence counter in vmf
>>> enable interrupt
>>> check vma sequence count
>>> handle_pte_fault(vma)
>>> ..
>>> page = alloc_page()
>>> pte_map_lock()
>>> disable interrupt
>>> abort if sequence counter has changed
>>> abort if pmd or pte has changed
>>> pte map and lock
>>> enable interrupt
>>> if abort
>>> free page
>>> abort
>>> ...
>>> }
>>>
>>> arch_fault_handler()
>>> {
>>> if (speculative_page_fault(&vma))
>>> goto done
>>> again:
>>> lock(mmap_sem)
>>> vma = find_vma();
>>> handle_pte_fault(vma);
>>> if retry
>>> unlock(mmap_sem)
>>> goto again;
>>> done:
>>> handle fault error
>>> }
>>>
>>> Support for THP is not done because when checking for the PMD, we can be
>>> confused by an in progress collapsing operation done by khugepaged. The
>>> issue is that pmd_none() could be true either if the PMD is not already
>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>> cannot safely allocate a PMD if pmd_none() is true.
>>>
>>> This series add a new software performance event named 'speculative-faults'
>>> or 'spf'. It counts the number of successful page fault event handled
>>> speculatively. When recording 'faults,spf' events, the faults one is
>>> counting the total number of page fault events while 'spf' is only counting
>>> the part of the faults processed speculatively.
>>>
>>> There are some trace events introduced by this series. They allow
>>> identifying why the page faults were not processed speculatively. This
>>> doesn't take in account the faults generated by a monothreaded process
>>> which directly processed while holding the mmap_sem. This trace events are
>>> grouped in a system named 'pagefault', they are:
>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>> back.
>>>
>>> To record all the related events, the easier is to run perf with the
>>> following arguments :
>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>
>>> There is also a dedicated vmstat counter showing the number of successful
>>> page fault handled speculatively. I can be seen this way:
>>> $ grep speculative_pgfault /proc/vmstat
>>>
>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>> on x86, PowerPC and arm64.
>>>
>>> ---------------------
>>> Real Workload results
>>>
>>> As mentioned in previous email, we did non official runs using a "popular
>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>> which showed a 30% improvements in the number of transaction processed per
>>> second. This run has been done on the v6 series, but changes introduced in
>>> this new version should not impact the performance boost seen.
>>>
>>> Here are the perf data captured during 2 of these runs on top of the v8
>>> series:
>>> vanilla spf
>>> faults 89.418 101.364 +13%
>>> spf n/a 97.989
>>>
>>> With the SPF kernel, most of the page fault were processed in a speculative
>>> way.
>>>
>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>> it a try on an android device. He reported that the application launch time
>>> was improved in average by 6%, and for large applications (~100 threads) by
>>> 20%.
>>>
>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>> MSM845 (8 cores) with 6GB (the less is better):
>>>
>>> Application 4.9 4.9+spf delta
>>> com.tencent.mm 416 389 -7%
>>> com.eg.android.AlipayGphone 1135 986 -13%
>>> com.tencent.mtt 455 454 0%
>>> com.qqgame.hlddz 1497 1409 -6%
>>> com.autonavi.minimap 711 701 -1%
>>> com.tencent.tmgp.sgame 788 748 -5%
>>> com.immomo.momo 501 487 -3%
>>> com.tencent.peng 2145 2112 -2%
>>> com.smile.gifmaker 491 461 -6%
>>> com.baidu.BaiduMap 479 366 -23%
>>> com.taobao.taobao 1341 1198 -11%
>>> com.baidu.searchbox 333 314 -6%
>>> com.tencent.mobileqq 394 384 -3%
>>> com.sina.weibo 907 906 0%
>>> com.youku.phone 816 731 -11%
>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>> com.UCMobile 415 411 -1%
>>> com.tencent.tmgp.ak 1464 1431 -2%
>>> com.tencent.qqmusic 336 329 -2%
>>> com.sankuai.meituan 1661 1302 -22%
>>> com.netease.cloudmusic 1193 1200 1%
>>> air.tv.douyu.android 4257 4152 -2%
>>>
>>> ------------------
>>> Benchmarks results
>>>
>>> Base kernel is v4.17.0-rc4-mm1
>>> SPF is BASE + this series
>>>
>>> Kernbench:
>>> ----------
>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>> kernel (kernel is build 5 times):
>>>
>>> Average Half load -j 8
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>
>>> Average Optimal load -j 16
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>
>>>
>>> During a run on the SPF, perf events were captured:
>>> Performance counter stats for '../kernbench -M':
>>> 526743764 faults
>>> 210 spf
>>> 3 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 2278 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> Very few speculative page faults were recorded as most of the processes
>>> involved are monothreaded (sounds that on this architecture some threads
>>> were created during the kernel build processing).
>>>
>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>
>>> Average Half load -j 40
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>
>>> Average Optimal load -j 80
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>
>>> During a run on the SPF, perf events were captured:
>>> Performance counter stats for '../kernbench -M':
>>> 116730856 faults
>>> 0 spf
>>> 3 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 476 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> Most of the processes involved are monothreaded so SPF is not activated but
>>> there is no impact on the performance.
>>>
>>> Ebizzy:
>>> -------
>>> The test is counting the number of records per second it can manage, the
>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>> consistent result I repeated the test 100 times and measure the average
>>> result. The number is the record processes per second, the higher is the
>>> best.
>>>
>>> BASE SPF delta
>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>
>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>> Performance counter stats for './ebizzy -mTt 16':
>>> 1706379 faults
>>> 1674599 spf
>>> 30588 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 363 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> And the ones captured during a run on a 80 CPUs Power node:
>>> Performance counter stats for './ebizzy -mTt 80':
>>> 1874773 faults
>>> 1461153 spf
>>> 413293 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 200 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>> leading the ebizzy performance boost.
>>>
>>> ------------------
>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>> and Minchan Kim, hopefully.
>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>> __do_page_fault().
>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>> instead
>>> of aborting the speculative page fault handling. Dropping the now
>>> useless
>>> trace event pagefault:spf_pte_lock.
>>> - No more try to reuse the fetched VMA during the speculative page fault
>>> handling when retrying is needed. This adds a lot of complexity and
>>> additional tests done didn't show a significant performance improvement.
>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>
>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>
>>>
>>> Laurent Dufour (20):
>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>> mm: make pte_unmap_same compatible with SPF
>>> mm: introduce INIT_VMA()
>>> mm: protect VMA modifications using VMA sequence count
>>> mm: protect mremap() against SPF hanlder
>>> mm: protect SPF handler against anon_vma changes
>>> mm: cache some VMA fields in the vm_fault structure
>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>> mm: introduce __lru_cache_add_active_or_unevictable
>>> mm: introduce __vm_normal_page()
>>> mm: introduce __page_add_new_anon_rmap()
>>> mm: protect mm_rb tree with a rwlock
>>> mm: adding speculative page fault failure trace events
>>> perf: add a speculative page fault sw event
>>> perf tools: add support for the SPF perf event
>>> mm: add speculative page fault vmstats
>>> powerpc/mm: add speculative page fault
>>>
>>> Mahendran Ganesh (2):
>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> arm64/mm: add speculative page fault
>>>
>>> Peter Zijlstra (4):
>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>> mm: VMA sequence count
>>> mm: provide speculative fault infrastructure
>>> x86/mm: add speculative pagefault handling
>>>
>>> arch/arm64/Kconfig | 1 +
>>> arch/arm64/mm/fault.c | 12 +
>>> arch/powerpc/Kconfig | 1 +
>>> arch/powerpc/mm/fault.c | 16 +
>>> arch/x86/Kconfig | 1 +
>>> arch/x86/mm/fault.c | 27 +-
>>> fs/exec.c | 2 +-
>>> fs/proc/task_mmu.c | 5 +-
>>> fs/userfaultfd.c | 17 +-
>>> include/linux/hugetlb_inline.h | 2 +-
>>> include/linux/migrate.h | 4 +-
>>> include/linux/mm.h | 136 +++++++-
>>> include/linux/mm_types.h | 7 +
>>> include/linux/pagemap.h | 4 +-
>>> include/linux/rmap.h | 12 +-
>>> include/linux/swap.h | 10 +-
>>> include/linux/vm_event_item.h | 3 +
>>> include/trace/events/pagefault.h | 80 +++++
>>> include/uapi/linux/perf_event.h | 1 +
>>> kernel/fork.c | 5 +-
>>> mm/Kconfig | 22 ++
>>> mm/huge_memory.c | 6 +-
>>> mm/hugetlb.c | 2 +
>>> mm/init-mm.c | 3 +
>>> mm/internal.h | 20 ++
>>> mm/khugepaged.c | 5 +
>>> mm/madvise.c | 6 +-
>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>> mm/mempolicy.c | 51 ++-
>>> mm/migrate.c | 6 +-
>>> mm/mlock.c | 13 +-
>>> mm/mmap.c | 229 ++++++++++---
>>> mm/mprotect.c | 4 +-
>>> mm/mremap.c | 13 +
>>> mm/nommu.c | 2 +-
>>> mm/rmap.c | 5 +-
>>> mm/swap.c | 6 +-
>>> mm/swap_state.c | 8 +-
>>> mm/vmstat.c | 5 +-
>>> tools/include/uapi/linux/perf_event.h | 1 +
>>> tools/perf/util/evsel.c | 1 +
>>> tools/perf/util/parse-events.c | 4 +
>>> tools/perf/util/parse-events.l | 1 +
>>> tools/perf/util/python.c | 1 +
>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>> create mode 100644 include/trace/events/pagefault.h
>>>
>>> --
>>> 2.7.4
>>>
>>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-05-28 8:54 ` Laurent Dufour
@ 2018-05-28 11:04 ` Wang, Kemi
2018-06-11 7:49 ` Song, HaiyanX
1 sibling, 0 replies; 46+ messages in thread
From: Wang, Kemi @ 2018-05-28 11:04 UTC (permalink / raw)
To: Laurent Dufour, Song, HaiyanX
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Daniel Jordan, David Rientjes, Jerome Glisse, Ganesh Mahendran,
Minchan Kim, Punit Agrawal, vinayak menon, Yang Shi,
linux-kernel, linux-mm, haren, npiggin, bsingharora, paulmck,
Tim Chen, linuxppc-dev, x86
Full run would take one or two weeks depended on our resource available. Could you pick some ones up, e.g. those have performance regression?
-----Original Message-----
From: owner-linux-mm@kvack.org [mailto:owner-linux-mm@kvack.org] On Behalf Of Laurent Dufour
Sent: Monday, May 28, 2018 4:55 PM
To: Song, HaiyanX <haiyanx.song@intel.com>
Cc: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox <willy@infradead.org>; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar <mingo@redhat.com>; hpa@zytor.com; Will Deacon <will.deacon@arm.com>; Sergey Senozhatsky <sergey.senozhatsky@gmail.com>; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli <aarcange@redhat.com>; Alexei Starovoitov <alexei.starovoitov@gmail.com>; Wang, Kemi <kemi.wang@intel.com>; Daniel Jordan <daniel.m.jordan@oracle.com>; David Rientjes <rientjes@google.com>; Jerome Glisse <jglisse@redhat.com>; Ganesh Mahendran <opensource.ganesh@gmail.com>; Minchan Kim <minchan@kernel.org>; Punit Agrawal <punitagrawal@gmail.com>; vinayak menon <vinayakm.list@gmail.com>; Yang Shi <yang.shi@linux.alibaba.com>; linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen <tim.c.chen@linux.intel.com>; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: Re: [PATCH v11 00/26] Speculative page faults
On 28/05/2018 10:22, Haiyan Song wrote:
> Hi Laurent,
>
> Yes, these tests are done on V9 patch.
Do you plan to give this V11 a run ?
>
>
> Best regards,
> Haiyan Song
>
> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>
>>> Some regression and improvements is found by LKP-tools(linux kernel
>>> performance) on V9 patch series tested on Intel 4s Skylake platform.
>>
>> Hi,
>>
>> Thanks for reporting this benchmark results, but you mentioned the
>> "V9 patch series" while responding to the v11 header series...
>> Were these tests done on v9 or v11 ?
>>
>> Cheers,
>> Laurent.
>>
>>>
>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9
>>> patch series) Commit id:
>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>> Benchmark suite: will-it-scale
>>> Download link:
>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>> Metrics:
>>> will-it-scale.per_process_ops=processes/nr_cpu
>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>> THP: enable / disable
>>> nr_task: 100%
>>>
>>> 1. Regressions:
>>> a) THP enabled:
>>> testcase base change head metric
>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>
>>> b) THP disabled:
>>> testcase base change head metric
>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>
>>> 2. Improvements:
>>> a) THP enabled:
>>> testcase base change head metric
>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>
>>> b) THP disabled:
>>> testcase base change head metric
>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>
>>> Notes: for above values in column "change", the higher value means
>>> that the related testcase result on head commit is better than that on base commit for this benchmark.
>>>
>>>
>>> Best regards
>>> Haiyan Song
>>>
>>> ________________________________________
>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf
>>> of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Thursday, May 17, 2018 7:06 PM
>>> To: akpm@linux-foundation.org; mhocko@kernel.org;
>>> peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com;
>>> dave@stgolabs.net; jack@suse.cz; Matthew Wilcox;
>>> khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com;
>>> benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org;
>>> Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey
>>> Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli;
>>> Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes;
>>> Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak
>>> menon; Yang Shi
>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org;
>>> haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com;
>>> paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org;
>>> x86@kernel.org
>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>
>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to
>>> handle page fault without holding the mm semaphore [1].
>>>
>>> The idea is to try to handle user space page faults without holding
>>> the mmap_sem. This should allow better concurrency for massively
>>> threaded process since the page fault handler will not wait for
>>> other threads memory layout change to be done, assuming that this
>>> change is done in another part of the process's memory space. This
>>> type page fault is named speculative page fault. If the speculative
>>> page fault fails because of a concurrency is detected or because
>>> underlying PMD or PTE tables are not yet allocating, it is failing its processing and a classic page fault is then tried.
>>>
>>> The speculative page fault (SPF) has to look for the VMA matching
>>> the fault address without holding the mmap_sem, this is done by
>>> introducing a rwlock which protects the access to the mm_rb tree.
>>> Previously this was done using SRCU but it was introducing a lot of
>>> scheduling to process the VMA's freeing operation which was hitting
>>> the performance by 20% as reported by Kemi Wang [2]. Using a rwlock
>>> to protect access to the mm_rb tree is limiting the locking
>>> contention to these operations which are expected to be in a O(log
>>> n) order. In addition to ensure that the VMA is not freed in our
>>> back a reference count is added and 2 services (get_vma() and
>>> put_vma()) are introduced to handle the reference count. Once a VMA
>>> is fetched from the RB tree using get_vma(), it must be later freed
>>> using put_vma(). I can't see anymore the overhead I got while
>>> will-it-scale benchmark anymore.
>>>
>>> The VMA's attributes checked during the speculative page fault
>>> processing have to be protected against parallel changes. This is
>>> done by using a per VMA sequence lock. This sequence lock allows the
>>> speculative page fault handler to fast check for parallel changes in
>>> progress and to abort the speculative page fault in that case.
>>>
>>> Once the VMA has been found, the speculative page fault handler
>>> would check for the VMA's attributes to verify that the page fault
>>> has to be handled correctly or not. Thus, the VMA is protected
>>> through a sequence lock which allows fast detection of concurrent
>>> VMA changes. If such a change is detected, the speculative page
>>> fault is aborted and a *classic* page fault is tried. VMA sequence
>>> lockings are added when VMA attributes which are checked during the page fault are modified.
>>>
>>> When the PTE is fetched, the VMA is checked to see if it has been
>>> changed, so once the page table is locked, the VMA is valid, so any
>>> other changes leading to touching this PTE will need to lock the
>>> page table, so no parallel change is possible at this time.
>>>
>>> The locking of the PTE is done with interrupts disabled, this allows
>>> checking for the PMD to ensure that there is not an ongoing
>>> collapsing operation. Since khugepaged is firstly set the PMD to
>>> pmd_none and then is waiting for the other CPU to have caught the
>>> IPI interrupt, if the pmd is valid at the time the PTE is locked, we
>>> have the guarantee that the collapsing operation will have to wait on the PTE lock to move forward.
>>> This allows the SPF handler to map the PTE safely. If the PMD value
>>> is different from the one recorded at the beginning of the SPF
>>> operation, the classic page fault handler will be called to handle
>>> the operation while holding the mmap_sem. As the PTE lock is done
>>> with the interrupts disabled, the lock is done using spin_trylock()
>>> to avoid dead lock when handling a page fault while a TLB invalidate
>>> is requested by another CPU holding the PTE.
>>>
>>> In pseudo code, this could be seen as:
>>> speculative_page_fault()
>>> {
>>> vma = get_vma()
>>> check vma sequence count
>>> check vma's support
>>> disable interrupt
>>> check pgd,p4d,...,pte
>>> save pmd and pte in vmf
>>> save vma sequence counter in vmf
>>> enable interrupt
>>> check vma sequence count
>>> handle_pte_fault(vma)
>>> ..
>>> page = alloc_page()
>>> pte_map_lock()
>>> disable interrupt
>>> abort if sequence counter has changed
>>> abort if pmd or pte has changed
>>> pte map and lock
>>> enable interrupt
>>> if abort
>>> free page
>>> abort
>>> ...
>>> }
>>>
>>> arch_fault_handler()
>>> {
>>> if (speculative_page_fault(&vma))
>>> goto done
>>> again:
>>> lock(mmap_sem)
>>> vma = find_vma();
>>> handle_pte_fault(vma);
>>> if retry
>>> unlock(mmap_sem)
>>> goto again;
>>> done:
>>> handle fault error
>>> }
>>>
>>> Support for THP is not done because when checking for the PMD, we
>>> can be confused by an in progress collapsing operation done by
>>> khugepaged. The issue is that pmd_none() could be true either if the
>>> PMD is not already populated or if the underlying PTE are in the way
>>> to be collapsed. So we cannot safely allocate a PMD if pmd_none() is true.
>>>
>>> This series add a new software performance event named 'speculative-faults'
>>> or 'spf'. It counts the number of successful page fault event
>>> handled speculatively. When recording 'faults,spf' events, the
>>> faults one is counting the total number of page fault events while
>>> 'spf' is only counting the part of the faults processed speculatively.
>>>
>>> There are some trace events introduced by this series. They allow
>>> identifying why the page faults were not processed speculatively.
>>> This doesn't take in account the faults generated by a monothreaded
>>> process which directly processed while holding the mmap_sem. This
>>> trace events are grouped in a system named 'pagefault', they are:
>>> - pagefault:spf_vma_changed : if the VMA has been changed in our
>>> back
>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>> - pagefault:spf_vma_access : the VMA's access right are not
>>> respected
>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>> back.
>>>
>>> To record all the related events, the easier is to run perf with the
>>> following arguments :
>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>
>>> There is also a dedicated vmstat counter showing the number of
>>> successful page fault handled speculatively. I can be seen this way:
>>> $ grep speculative_pgfault /proc/vmstat
>>>
>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is
>>> functional on x86, PowerPC and arm64.
>>>
>>> ---------------------
>>> Real Workload results
>>>
>>> As mentioned in previous email, we did non official runs using a
>>> "popular in memory multithreaded database product" on 176 cores SMT8
>>> Power system which showed a 30% improvements in the number of
>>> transaction processed per second. This run has been done on the v6
>>> series, but changes introduced in this new version should not impact the performance boost seen.
>>>
>>> Here are the perf data captured during 2 of these runs on top of the
>>> v8
>>> series:
>>> vanilla spf
>>> faults 89.418 101.364 +13%
>>> spf n/a 97.989
>>>
>>> With the SPF kernel, most of the page fault were processed in a
>>> speculative way.
>>>
>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel
>>> and gave it a try on an android device. He reported that the
>>> application launch time was improved in average by 6%, and for large
>>> applications (~100 threads) by 20%.
>>>
>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a
>>> Qcom
>>> MSM845 (8 cores) with 6GB (the less is better):
>>>
>>> Application 4.9 4.9+spf delta
>>> com.tencent.mm 416 389 -7%
>>> com.eg.android.AlipayGphone 1135 986 -13%
>>> com.tencent.mtt 455 454 0%
>>> com.qqgame.hlddz 1497 1409 -6%
>>> com.autonavi.minimap 711 701 -1%
>>> com.tencent.tmgp.sgame 788 748 -5%
>>> com.immomo.momo 501 487 -3%
>>> com.tencent.peng 2145 2112 -2%
>>> com.smile.gifmaker 491 461 -6%
>>> com.baidu.BaiduMap 479 366 -23%
>>> com.taobao.taobao 1341 1198 -11%
>>> com.baidu.searchbox 333 314 -6%
>>> com.tencent.mobileqq 394 384 -3%
>>> com.sina.weibo 907 906 0%
>>> com.youku.phone 816 731 -11%
>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>> com.UCMobile 415 411 -1%
>>> com.tencent.tmgp.ak 1464 1431 -2%
>>> com.tencent.qqmusic 336 329 -2%
>>> com.sankuai.meituan 1661 1302 -22%
>>> com.netease.cloudmusic 1193 1200 1%
>>> air.tv.douyu.android 4257 4152 -2%
>>>
>>> ------------------
>>> Benchmarks results
>>>
>>> Base kernel is v4.17.0-rc4-mm1
>>> SPF is BASE + this series
>>>
>>> Kernbench:
>>> ----------
>>> Here are the results on a 16 CPUs X86 guest using kernbench on a
>>> 4.15 kernel (kernel is build 5 times):
>>>
>>> Average Half load -j 8
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>
>>> Average Optimal load -j 16
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>
>>>
>>> During a run on the SPF, perf events were captured:
>>> Performance counter stats for '../kernbench -M':
>>> 526743764 faults
>>> 210 spf
>>> 3 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 2278 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> Very few speculative page faults were recorded as most of the
>>> processes involved are monothreaded (sounds that on this
>>> architecture some threads were created during the kernel build processing).
>>>
>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>
>>> Average Half load -j 40
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>
>>> Average Optimal load -j 80
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>
>>> During a run on the SPF, perf events were captured:
>>> Performance counter stats for '../kernbench -M':
>>> 116730856 faults
>>> 0 spf
>>> 3 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 476 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> Most of the processes involved are monothreaded so SPF is not
>>> activated but there is no impact on the performance.
>>>
>>> Ebizzy:
>>> -------
>>> The test is counting the number of records per second it can manage,
>>> the higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'.
>>> To get consistent result I repeated the test 100 times and measure
>>> the average result. The number is the record processes per second,
>>> the higher is the best.
>>>
>>> BASE SPF delta
>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>
>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>> Performance counter stats for './ebizzy -mTt 16':
>>> 1706379 faults
>>> 1674599 spf
>>> 30588 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 363 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> And the ones captured during a run on a 80 CPUs Power node:
>>> Performance counter stats for './ebizzy -mTt 80':
>>> 1874773 faults
>>> 1461153 spf
>>> 413293 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 200 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> In ebizzy's case most of the page fault were handled in a
>>> speculative way, leading the ebizzy performance boost.
>>>
>>> ------------------
>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>> and Minchan Kim, hopefully.
>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>> __do_page_fault().
>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>> instead
>>> of aborting the speculative page fault handling. Dropping the now
>>> useless
>>> trace event pagefault:spf_pte_lock.
>>> - No more try to reuse the fetched VMA during the speculative page fault
>>> handling when retrying is needed. This adds a lot of complexity and
>>> additional tests done didn't show a significant performance improvement.
>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>
>>> [1]
>>> http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-s
>>> peculative-page-faults-tt965642.html#none
>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>
>>>
>>> Laurent Dufour (20):
>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>> mm: make pte_unmap_same compatible with SPF
>>> mm: introduce INIT_VMA()
>>> mm: protect VMA modifications using VMA sequence count
>>> mm: protect mremap() against SPF hanlder
>>> mm: protect SPF handler against anon_vma changes
>>> mm: cache some VMA fields in the vm_fault structure
>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>> mm: introduce __lru_cache_add_active_or_unevictable
>>> mm: introduce __vm_normal_page()
>>> mm: introduce __page_add_new_anon_rmap()
>>> mm: protect mm_rb tree with a rwlock
>>> mm: adding speculative page fault failure trace events
>>> perf: add a speculative page fault sw event
>>> perf tools: add support for the SPF perf event
>>> mm: add speculative page fault vmstats
>>> powerpc/mm: add speculative page fault
>>>
>>> Mahendran Ganesh (2):
>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> arm64/mm: add speculative page fault
>>>
>>> Peter Zijlstra (4):
>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>> mm: VMA sequence count
>>> mm: provide speculative fault infrastructure
>>> x86/mm: add speculative pagefault handling
>>>
>>> arch/arm64/Kconfig | 1 +
>>> arch/arm64/mm/fault.c | 12 +
>>> arch/powerpc/Kconfig | 1 +
>>> arch/powerpc/mm/fault.c | 16 +
>>> arch/x86/Kconfig | 1 +
>>> arch/x86/mm/fault.c | 27 +-
>>> fs/exec.c | 2 +-
>>> fs/proc/task_mmu.c | 5 +-
>>> fs/userfaultfd.c | 17 +-
>>> include/linux/hugetlb_inline.h | 2 +-
>>> include/linux/migrate.h | 4 +-
>>> include/linux/mm.h | 136 +++++++-
>>> include/linux/mm_types.h | 7 +
>>> include/linux/pagemap.h | 4 +-
>>> include/linux/rmap.h | 12 +-
>>> include/linux/swap.h | 10 +-
>>> include/linux/vm_event_item.h | 3 +
>>> include/trace/events/pagefault.h | 80 +++++
>>> include/uapi/linux/perf_event.h | 1 +
>>> kernel/fork.c | 5 +-
>>> mm/Kconfig | 22 ++
>>> mm/huge_memory.c | 6 +-
>>> mm/hugetlb.c | 2 +
>>> mm/init-mm.c | 3 +
>>> mm/internal.h | 20 ++
>>> mm/khugepaged.c | 5 +
>>> mm/madvise.c | 6 +-
>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>> mm/mempolicy.c | 51 ++-
>>> mm/migrate.c | 6 +-
>>> mm/mlock.c | 13 +-
>>> mm/mmap.c | 229 ++++++++++---
>>> mm/mprotect.c | 4 +-
>>> mm/mremap.c | 13 +
>>> mm/nommu.c | 2 +-
>>> mm/rmap.c | 5 +-
>>> mm/swap.c | 6 +-
>>> mm/swap_state.c | 8 +-
>>> mm/vmstat.c | 5 +-
>>> tools/include/uapi/linux/perf_event.h | 1 +
>>> tools/perf/util/evsel.c | 1 +
>>> tools/perf/util/parse-events.c | 4 +
>>> tools/perf/util/parse-events.l | 1 +
>>> tools/perf/util/python.c | 1 +
>>> 44 files changed, 1161 insertions(+), 211 deletions(-) create mode
>>> 100644 include/trace/events/pagefault.h
>>>
>>> --
>>> 2.7.4
>>>
>>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-05-28 8:22 ` Haiyan Song
@ 2018-05-28 8:54 ` Laurent Dufour
2018-05-28 11:04 ` Wang, Kemi
2018-06-11 7:49 ` Song, HaiyanX
0 siblings, 2 replies; 46+ messages in thread
From: Laurent Dufour @ 2018-05-28 8:54 UTC (permalink / raw)
To: Haiyan Song
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
On 28/05/2018 10:22, Haiyan Song wrote:
> Hi Laurent,
>
> Yes, these tests are done on V9 patch.
Do you plan to give this V11 a run ?
>
>
> Best regards,
> Haiyan Song
>
> On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
>> On 28/05/2018 07:23, Song, HaiyanX wrote:
>>>
>>> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
>>> tested on Intel 4s Skylake platform.
>>
>> Hi,
>>
>> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
>> series" while responding to the v11 header series...
>> Were these tests done on v9 or v11 ?
>>
>> Cheers,
>> Laurent.
>>
>>>
>>> The regression result is sorted by the metric will-it-scale.per_thread_ops.
>>> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
>>> Commit id:
>>> base commit: d55f34411b1b126429a823d06c3124c16283231f
>>> head commit: 0355322b3577eeab7669066df42c550a56801110
>>> Benchmark suite: will-it-scale
>>> Download link:
>>> https://github.com/antonblanchard/will-it-scale/tree/master/tests
>>> Metrics:
>>> will-it-scale.per_process_ops=processes/nr_cpu
>>> will-it-scale.per_thread_ops=threads/nr_cpu
>>> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
>>> THP: enable / disable
>>> nr_task: 100%
>>>
>>> 1. Regressions:
>>> a) THP enabled:
>>> testcase base change head metric
>>> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
>>> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
>>> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
>>> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
>>> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>>>
>>> b) THP disabled:
>>> testcase base change head metric
>>> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
>>> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
>>> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
>>> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
>>> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
>>> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>>>
>>> 2. Improvements:
>>> a) THP enabled:
>>> testcase base change head metric
>>> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
>>> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
>>> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>>>
>>> b) THP disabled:
>>> testcase base change head metric
>>> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
>>> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
>>> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
>>> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
>>> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
>>> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>>>
>>> Notes: for above values in column "change", the higher value means that the related testcase result
>>> on head commit is better than that on base commit for this benchmark.
>>>
>>>
>>> Best regards
>>> Haiyan Song
>>>
>>> ________________________________________
>>> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
>>> Sent: Thursday, May 17, 2018 7:06 PM
>>> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
>>> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
>>> Subject: [PATCH v11 00/26] Speculative page faults
>>>
>>> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
>>> page fault without holding the mm semaphore [1].
>>>
>>> The idea is to try to handle user space page faults without holding the
>>> mmap_sem. This should allow better concurrency for massively threaded
>>> process since the page fault handler will not wait for other threads memory
>>> layout change to be done, assuming that this change is done in another part
>>> of the process's memory space. This type page fault is named speculative
>>> page fault. If the speculative page fault fails because of a concurrency is
>>> detected or because underlying PMD or PTE tables are not yet allocating, it
>>> is failing its processing and a classic page fault is then tried.
>>>
>>> The speculative page fault (SPF) has to look for the VMA matching the fault
>>> address without holding the mmap_sem, this is done by introducing a rwlock
>>> which protects the access to the mm_rb tree. Previously this was done using
>>> SRCU but it was introducing a lot of scheduling to process the VMA's
>>> freeing operation which was hitting the performance by 20% as reported by
>>> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
>>> limiting the locking contention to these operations which are expected to
>>> be in a O(log n) order. In addition to ensure that the VMA is not freed in
>>> our back a reference count is added and 2 services (get_vma() and
>>> put_vma()) are introduced to handle the reference count. Once a VMA is
>>> fetched from the RB tree using get_vma(), it must be later freed using
>>> put_vma(). I can't see anymore the overhead I got while will-it-scale
>>> benchmark anymore.
>>>
>>> The VMA's attributes checked during the speculative page fault processing
>>> have to be protected against parallel changes. This is done by using a per
>>> VMA sequence lock. This sequence lock allows the speculative page fault
>>> handler to fast check for parallel changes in progress and to abort the
>>> speculative page fault in that case.
>>>
>>> Once the VMA has been found, the speculative page fault handler would check
>>> for the VMA's attributes to verify that the page fault has to be handled
>>> correctly or not. Thus, the VMA is protected through a sequence lock which
>>> allows fast detection of concurrent VMA changes. If such a change is
>>> detected, the speculative page fault is aborted and a *classic* page fault
>>> is tried. VMA sequence lockings are added when VMA attributes which are
>>> checked during the page fault are modified.
>>>
>>> When the PTE is fetched, the VMA is checked to see if it has been changed,
>>> so once the page table is locked, the VMA is valid, so any other changes
>>> leading to touching this PTE will need to lock the page table, so no
>>> parallel change is possible at this time.
>>>
>>> The locking of the PTE is done with interrupts disabled, this allows
>>> checking for the PMD to ensure that there is not an ongoing collapsing
>>> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
>>> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
>>> valid at the time the PTE is locked, we have the guarantee that the
>>> collapsing operation will have to wait on the PTE lock to move forward.
>>> This allows the SPF handler to map the PTE safely. If the PMD value is
>>> different from the one recorded at the beginning of the SPF operation, the
>>> classic page fault handler will be called to handle the operation while
>>> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
>>> the lock is done using spin_trylock() to avoid dead lock when handling a
>>> page fault while a TLB invalidate is requested by another CPU holding the
>>> PTE.
>>>
>>> In pseudo code, this could be seen as:
>>> speculative_page_fault()
>>> {
>>> vma = get_vma()
>>> check vma sequence count
>>> check vma's support
>>> disable interrupt
>>> check pgd,p4d,...,pte
>>> save pmd and pte in vmf
>>> save vma sequence counter in vmf
>>> enable interrupt
>>> check vma sequence count
>>> handle_pte_fault(vma)
>>> ..
>>> page = alloc_page()
>>> pte_map_lock()
>>> disable interrupt
>>> abort if sequence counter has changed
>>> abort if pmd or pte has changed
>>> pte map and lock
>>> enable interrupt
>>> if abort
>>> free page
>>> abort
>>> ...
>>> }
>>>
>>> arch_fault_handler()
>>> {
>>> if (speculative_page_fault(&vma))
>>> goto done
>>> again:
>>> lock(mmap_sem)
>>> vma = find_vma();
>>> handle_pte_fault(vma);
>>> if retry
>>> unlock(mmap_sem)
>>> goto again;
>>> done:
>>> handle fault error
>>> }
>>>
>>> Support for THP is not done because when checking for the PMD, we can be
>>> confused by an in progress collapsing operation done by khugepaged. The
>>> issue is that pmd_none() could be true either if the PMD is not already
>>> populated or if the underlying PTE are in the way to be collapsed. So we
>>> cannot safely allocate a PMD if pmd_none() is true.
>>>
>>> This series add a new software performance event named 'speculative-faults'
>>> or 'spf'. It counts the number of successful page fault event handled
>>> speculatively. When recording 'faults,spf' events, the faults one is
>>> counting the total number of page fault events while 'spf' is only counting
>>> the part of the faults processed speculatively.
>>>
>>> There are some trace events introduced by this series. They allow
>>> identifying why the page faults were not processed speculatively. This
>>> doesn't take in account the faults generated by a monothreaded process
>>> which directly processed while holding the mmap_sem. This trace events are
>>> grouped in a system named 'pagefault', they are:
>>> - pagefault:spf_vma_changed : if the VMA has been changed in our back
>>> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
>>> - pagefault:spf_vma_notsup : the VMA's type is not supported
>>> - pagefault:spf_vma_access : the VMA's access right are not respected
>>> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
>>> back.
>>>
>>> To record all the related events, the easier is to run perf with the
>>> following arguments :
>>> $ perf stat -e 'faults,spf,pagefault:*' <command>
>>>
>>> There is also a dedicated vmstat counter showing the number of successful
>>> page fault handled speculatively. I can be seen this way:
>>> $ grep speculative_pgfault /proc/vmstat
>>>
>>> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
>>> on x86, PowerPC and arm64.
>>>
>>> ---------------------
>>> Real Workload results
>>>
>>> As mentioned in previous email, we did non official runs using a "popular
>>> in memory multithreaded database product" on 176 cores SMT8 Power system
>>> which showed a 30% improvements in the number of transaction processed per
>>> second. This run has been done on the v6 series, but changes introduced in
>>> this new version should not impact the performance boost seen.
>>>
>>> Here are the perf data captured during 2 of these runs on top of the v8
>>> series:
>>> vanilla spf
>>> faults 89.418 101.364 +13%
>>> spf n/a 97.989
>>>
>>> With the SPF kernel, most of the page fault were processed in a speculative
>>> way.
>>>
>>> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
>>> it a try on an android device. He reported that the application launch time
>>> was improved in average by 6%, and for large applications (~100 threads) by
>>> 20%.
>>>
>>> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
>>> MSM845 (8 cores) with 6GB (the less is better):
>>>
>>> Application 4.9 4.9+spf delta
>>> com.tencent.mm 416 389 -7%
>>> com.eg.android.AlipayGphone 1135 986 -13%
>>> com.tencent.mtt 455 454 0%
>>> com.qqgame.hlddz 1497 1409 -6%
>>> com.autonavi.minimap 711 701 -1%
>>> com.tencent.tmgp.sgame 788 748 -5%
>>> com.immomo.momo 501 487 -3%
>>> com.tencent.peng 2145 2112 -2%
>>> com.smile.gifmaker 491 461 -6%
>>> com.baidu.BaiduMap 479 366 -23%
>>> com.taobao.taobao 1341 1198 -11%
>>> com.baidu.searchbox 333 314 -6%
>>> com.tencent.mobileqq 394 384 -3%
>>> com.sina.weibo 907 906 0%
>>> com.youku.phone 816 731 -11%
>>> com.happyelements.AndroidAnimal.qq 763 717 -6%
>>> com.UCMobile 415 411 -1%
>>> com.tencent.tmgp.ak 1464 1431 -2%
>>> com.tencent.qqmusic 336 329 -2%
>>> com.sankuai.meituan 1661 1302 -22%
>>> com.netease.cloudmusic 1193 1200 1%
>>> air.tv.douyu.android 4257 4152 -2%
>>>
>>> ------------------
>>> Benchmarks results
>>>
>>> Base kernel is v4.17.0-rc4-mm1
>>> SPF is BASE + this series
>>>
>>> Kernbench:
>>> ----------
>>> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
>>> kernel (kernel is build 5 times):
>>>
>>> Average Half load -j 8
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
>>> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
>>> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
>>> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
>>> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
>>> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>>>
>>> Average Optimal load -j 16
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
>>> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
>>> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
>>> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
>>> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
>>> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>>>
>>>
>>> During a run on the SPF, perf events were captured:
>>> Performance counter stats for '../kernbench -M':
>>> 526743764 faults
>>> 210 spf
>>> 3 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 2278 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> Very few speculative page faults were recorded as most of the processes
>>> involved are monothreaded (sounds that on this architecture some threads
>>> were created during the kernel build processing).
>>>
>>> Here are the kerbench results on a 80 CPUs Power8 system:
>>>
>>> Average Half load -j 40
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
>>> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
>>> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
>>> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
>>> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
>>> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>>>
>>> Average Optimal load -j 80
>>> Run (std deviation)
>>> BASE SPF
>>> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
>>> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
>>> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
>>> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
>>> Context Switches 223861 (138865) 225032 (139632) 0.52%
>>> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>>>
>>> During a run on the SPF, perf events were captured:
>>> Performance counter stats for '../kernbench -M':
>>> 116730856 faults
>>> 0 spf
>>> 3 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 476 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> Most of the processes involved are monothreaded so SPF is not activated but
>>> there is no impact on the performance.
>>>
>>> Ebizzy:
>>> -------
>>> The test is counting the number of records per second it can manage, the
>>> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
>>> consistent result I repeated the test 100 times and measure the average
>>> result. The number is the record processes per second, the higher is the
>>> best.
>>>
>>> BASE SPF delta
>>> 16 CPUs x86 VM 742.57 1490.24 100.69%
>>> 80 CPUs P8 node 13105.4 24174.23 84.46%
>>>
>>> Here are the performance counter read during a run on a 16 CPUs x86 VM:
>>> Performance counter stats for './ebizzy -mTt 16':
>>> 1706379 faults
>>> 1674599 spf
>>> 30588 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 363 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> And the ones captured during a run on a 80 CPUs Power node:
>>> Performance counter stats for './ebizzy -mTt 80':
>>> 1874773 faults
>>> 1461153 spf
>>> 413293 pagefault:spf_vma_changed
>>> 0 pagefault:spf_vma_noanon
>>> 200 pagefault:spf_vma_notsup
>>> 0 pagefault:spf_vma_access
>>> 0 pagefault:spf_pmd_changed
>>>
>>> In ebizzy's case most of the page fault were handled in a speculative way,
>>> leading the ebizzy performance boost.
>>>
>>> ------------------
>>> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
>>> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
>>> and Minchan Kim, hopefully.
>>> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
>>> __do_page_fault().
>>> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
>>> instead
>>> of aborting the speculative page fault handling. Dropping the now
>>> useless
>>> trace event pagefault:spf_pte_lock.
>>> - No more try to reuse the fetched VMA during the speculative page fault
>>> handling when retrying is needed. This adds a lot of complexity and
>>> additional tests done didn't show a significant performance improvement.
>>> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>>>
>>> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
>>> [2] https://patchwork.kernel.org/patch/9999687/
>>>
>>>
>>> Laurent Dufour (20):
>>> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
>>> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
>>> mm: make pte_unmap_same compatible with SPF
>>> mm: introduce INIT_VMA()
>>> mm: protect VMA modifications using VMA sequence count
>>> mm: protect mremap() against SPF hanlder
>>> mm: protect SPF handler against anon_vma changes
>>> mm: cache some VMA fields in the vm_fault structure
>>> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
>>> mm: introduce __lru_cache_add_active_or_unevictable
>>> mm: introduce __vm_normal_page()
>>> mm: introduce __page_add_new_anon_rmap()
>>> mm: protect mm_rb tree with a rwlock
>>> mm: adding speculative page fault failure trace events
>>> perf: add a speculative page fault sw event
>>> perf tools: add support for the SPF perf event
>>> mm: add speculative page fault vmstats
>>> powerpc/mm: add speculative page fault
>>>
>>> Mahendran Ganesh (2):
>>> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>> arm64/mm: add speculative page fault
>>>
>>> Peter Zijlstra (4):
>>> mm: prepare for FAULT_FLAG_SPECULATIVE
>>> mm: VMA sequence count
>>> mm: provide speculative fault infrastructure
>>> x86/mm: add speculative pagefault handling
>>>
>>> arch/arm64/Kconfig | 1 +
>>> arch/arm64/mm/fault.c | 12 +
>>> arch/powerpc/Kconfig | 1 +
>>> arch/powerpc/mm/fault.c | 16 +
>>> arch/x86/Kconfig | 1 +
>>> arch/x86/mm/fault.c | 27 +-
>>> fs/exec.c | 2 +-
>>> fs/proc/task_mmu.c | 5 +-
>>> fs/userfaultfd.c | 17 +-
>>> include/linux/hugetlb_inline.h | 2 +-
>>> include/linux/migrate.h | 4 +-
>>> include/linux/mm.h | 136 +++++++-
>>> include/linux/mm_types.h | 7 +
>>> include/linux/pagemap.h | 4 +-
>>> include/linux/rmap.h | 12 +-
>>> include/linux/swap.h | 10 +-
>>> include/linux/vm_event_item.h | 3 +
>>> include/trace/events/pagefault.h | 80 +++++
>>> include/uapi/linux/perf_event.h | 1 +
>>> kernel/fork.c | 5 +-
>>> mm/Kconfig | 22 ++
>>> mm/huge_memory.c | 6 +-
>>> mm/hugetlb.c | 2 +
>>> mm/init-mm.c | 3 +
>>> mm/internal.h | 20 ++
>>> mm/khugepaged.c | 5 +
>>> mm/madvise.c | 6 +-
>>> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
>>> mm/mempolicy.c | 51 ++-
>>> mm/migrate.c | 6 +-
>>> mm/mlock.c | 13 +-
>>> mm/mmap.c | 229 ++++++++++---
>>> mm/mprotect.c | 4 +-
>>> mm/mremap.c | 13 +
>>> mm/nommu.c | 2 +-
>>> mm/rmap.c | 5 +-
>>> mm/swap.c | 6 +-
>>> mm/swap_state.c | 8 +-
>>> mm/vmstat.c | 5 +-
>>> tools/include/uapi/linux/perf_event.h | 1 +
>>> tools/perf/util/evsel.c | 1 +
>>> tools/perf/util/parse-events.c | 4 +
>>> tools/perf/util/parse-events.l | 1 +
>>> tools/perf/util/python.c | 1 +
>>> 44 files changed, 1161 insertions(+), 211 deletions(-)
>>> create mode 100644 include/trace/events/pagefault.h
>>>
>>> --
>>> 2.7.4
>>>
>>>
>>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-05-28 7:51 ` Laurent Dufour
@ 2018-05-28 8:22 ` Haiyan Song
2018-05-28 8:54 ` Laurent Dufour
0 siblings, 1 reply; 46+ messages in thread
From: Haiyan Song @ 2018-05-28 8:22 UTC (permalink / raw)
To: Laurent Dufour
Cc: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
Wang, Kemi, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi, linux-kernel, linux-mm, haren, npiggin, bsingharora,
paulmck, Tim Chen, linuxppc-dev, x86
Hi Laurent,
Yes, these tests are done on V9 patch.
Best regards,
Haiyan Song
On Mon, May 28, 2018 at 09:51:34AM +0200, Laurent Dufour wrote:
> On 28/05/2018 07:23, Song, HaiyanX wrote:
> >
> > Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
> > tested on Intel 4s Skylake platform.
>
> Hi,
>
> Thanks for reporting this benchmark results, but you mentioned the "V9 patch
> series" while responding to the v11 header series...
> Were these tests done on v9 or v11 ?
>
> Cheers,
> Laurent.
>
> >
> > The regression result is sorted by the metric will-it-scale.per_thread_ops.
> > Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
> > Commit id:
> > base commit: d55f34411b1b126429a823d06c3124c16283231f
> > head commit: 0355322b3577eeab7669066df42c550a56801110
> > Benchmark suite: will-it-scale
> > Download link:
> > https://github.com/antonblanchard/will-it-scale/tree/master/tests
> > Metrics:
> > will-it-scale.per_process_ops=processes/nr_cpu
> > will-it-scale.per_thread_ops=threads/nr_cpu
> > test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
> > THP: enable / disable
> > nr_task: 100%
> >
> > 1. Regressions:
> > a) THP enabled:
> > testcase base change head metric
> > page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
> > page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
> > brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
> > page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
> > signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
> >
> > b) THP disabled:
> > testcase base change head metric
> > page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
> > page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
> > context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
> > brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
> > page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
> > signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
> >
> > 2. Improvements:
> > a) THP enabled:
> > testcase base change head metric
> > malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
> > writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
> > signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
> >
> > b) THP disabled:
> > testcase base change head metric
> > malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
> > read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
> > page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
> > read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
> > writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
> > signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
> >
> > Notes: for above values in column "change", the higher value means that the related testcase result
> > on head commit is better than that on base commit for this benchmark.
> >
> >
> > Best regards
> > Haiyan Song
> >
> > ________________________________________
> > From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> > Sent: Thursday, May 17, 2018 7:06 PM
> > To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
> > Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> > Subject: [PATCH v11 00/26] Speculative page faults
> >
> > This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
> > page fault without holding the mm semaphore [1].
> >
> > The idea is to try to handle user space page faults without holding the
> > mmap_sem. This should allow better concurrency for massively threaded
> > process since the page fault handler will not wait for other threads memory
> > layout change to be done, assuming that this change is done in another part
> > of the process's memory space. This type page fault is named speculative
> > page fault. If the speculative page fault fails because of a concurrency is
> > detected or because underlying PMD or PTE tables are not yet allocating, it
> > is failing its processing and a classic page fault is then tried.
> >
> > The speculative page fault (SPF) has to look for the VMA matching the fault
> > address without holding the mmap_sem, this is done by introducing a rwlock
> > which protects the access to the mm_rb tree. Previously this was done using
> > SRCU but it was introducing a lot of scheduling to process the VMA's
> > freeing operation which was hitting the performance by 20% as reported by
> > Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
> > limiting the locking contention to these operations which are expected to
> > be in a O(log n) order. In addition to ensure that the VMA is not freed in
> > our back a reference count is added and 2 services (get_vma() and
> > put_vma()) are introduced to handle the reference count. Once a VMA is
> > fetched from the RB tree using get_vma(), it must be later freed using
> > put_vma(). I can't see anymore the overhead I got while will-it-scale
> > benchmark anymore.
> >
> > The VMA's attributes checked during the speculative page fault processing
> > have to be protected against parallel changes. This is done by using a per
> > VMA sequence lock. This sequence lock allows the speculative page fault
> > handler to fast check for parallel changes in progress and to abort the
> > speculative page fault in that case.
> >
> > Once the VMA has been found, the speculative page fault handler would check
> > for the VMA's attributes to verify that the page fault has to be handled
> > correctly or not. Thus, the VMA is protected through a sequence lock which
> > allows fast detection of concurrent VMA changes. If such a change is
> > detected, the speculative page fault is aborted and a *classic* page fault
> > is tried. VMA sequence lockings are added when VMA attributes which are
> > checked during the page fault are modified.
> >
> > When the PTE is fetched, the VMA is checked to see if it has been changed,
> > so once the page table is locked, the VMA is valid, so any other changes
> > leading to touching this PTE will need to lock the page table, so no
> > parallel change is possible at this time.
> >
> > The locking of the PTE is done with interrupts disabled, this allows
> > checking for the PMD to ensure that there is not an ongoing collapsing
> > operation. Since khugepaged is firstly set the PMD to pmd_none and then is
> > waiting for the other CPU to have caught the IPI interrupt, if the pmd is
> > valid at the time the PTE is locked, we have the guarantee that the
> > collapsing operation will have to wait on the PTE lock to move forward.
> > This allows the SPF handler to map the PTE safely. If the PMD value is
> > different from the one recorded at the beginning of the SPF operation, the
> > classic page fault handler will be called to handle the operation while
> > holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
> > the lock is done using spin_trylock() to avoid dead lock when handling a
> > page fault while a TLB invalidate is requested by another CPU holding the
> > PTE.
> >
> > In pseudo code, this could be seen as:
> > speculative_page_fault()
> > {
> > vma = get_vma()
> > check vma sequence count
> > check vma's support
> > disable interrupt
> > check pgd,p4d,...,pte
> > save pmd and pte in vmf
> > save vma sequence counter in vmf
> > enable interrupt
> > check vma sequence count
> > handle_pte_fault(vma)
> > ..
> > page = alloc_page()
> > pte_map_lock()
> > disable interrupt
> > abort if sequence counter has changed
> > abort if pmd or pte has changed
> > pte map and lock
> > enable interrupt
> > if abort
> > free page
> > abort
> > ...
> > }
> >
> > arch_fault_handler()
> > {
> > if (speculative_page_fault(&vma))
> > goto done
> > again:
> > lock(mmap_sem)
> > vma = find_vma();
> > handle_pte_fault(vma);
> > if retry
> > unlock(mmap_sem)
> > goto again;
> > done:
> > handle fault error
> > }
> >
> > Support for THP is not done because when checking for the PMD, we can be
> > confused by an in progress collapsing operation done by khugepaged. The
> > issue is that pmd_none() could be true either if the PMD is not already
> > populated or if the underlying PTE are in the way to be collapsed. So we
> > cannot safely allocate a PMD if pmd_none() is true.
> >
> > This series add a new software performance event named 'speculative-faults'
> > or 'spf'. It counts the number of successful page fault event handled
> > speculatively. When recording 'faults,spf' events, the faults one is
> > counting the total number of page fault events while 'spf' is only counting
> > the part of the faults processed speculatively.
> >
> > There are some trace events introduced by this series. They allow
> > identifying why the page faults were not processed speculatively. This
> > doesn't take in account the faults generated by a monothreaded process
> > which directly processed while holding the mmap_sem. This trace events are
> > grouped in a system named 'pagefault', they are:
> > - pagefault:spf_vma_changed : if the VMA has been changed in our back
> > - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
> > - pagefault:spf_vma_notsup : the VMA's type is not supported
> > - pagefault:spf_vma_access : the VMA's access right are not respected
> > - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
> > back.
> >
> > To record all the related events, the easier is to run perf with the
> > following arguments :
> > $ perf stat -e 'faults,spf,pagefault:*' <command>
> >
> > There is also a dedicated vmstat counter showing the number of successful
> > page fault handled speculatively. I can be seen this way:
> > $ grep speculative_pgfault /proc/vmstat
> >
> > This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
> > on x86, PowerPC and arm64.
> >
> > ---------------------
> > Real Workload results
> >
> > As mentioned in previous email, we did non official runs using a "popular
> > in memory multithreaded database product" on 176 cores SMT8 Power system
> > which showed a 30% improvements in the number of transaction processed per
> > second. This run has been done on the v6 series, but changes introduced in
> > this new version should not impact the performance boost seen.
> >
> > Here are the perf data captured during 2 of these runs on top of the v8
> > series:
> > vanilla spf
> > faults 89.418 101.364 +13%
> > spf n/a 97.989
> >
> > With the SPF kernel, most of the page fault were processed in a speculative
> > way.
> >
> > Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
> > it a try on an android device. He reported that the application launch time
> > was improved in average by 6%, and for large applications (~100 threads) by
> > 20%.
> >
> > Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
> > MSM845 (8 cores) with 6GB (the less is better):
> >
> > Application 4.9 4.9+spf delta
> > com.tencent.mm 416 389 -7%
> > com.eg.android.AlipayGphone 1135 986 -13%
> > com.tencent.mtt 455 454 0%
> > com.qqgame.hlddz 1497 1409 -6%
> > com.autonavi.minimap 711 701 -1%
> > com.tencent.tmgp.sgame 788 748 -5%
> > com.immomo.momo 501 487 -3%
> > com.tencent.peng 2145 2112 -2%
> > com.smile.gifmaker 491 461 -6%
> > com.baidu.BaiduMap 479 366 -23%
> > com.taobao.taobao 1341 1198 -11%
> > com.baidu.searchbox 333 314 -6%
> > com.tencent.mobileqq 394 384 -3%
> > com.sina.weibo 907 906 0%
> > com.youku.phone 816 731 -11%
> > com.happyelements.AndroidAnimal.qq 763 717 -6%
> > com.UCMobile 415 411 -1%
> > com.tencent.tmgp.ak 1464 1431 -2%
> > com.tencent.qqmusic 336 329 -2%
> > com.sankuai.meituan 1661 1302 -22%
> > com.netease.cloudmusic 1193 1200 1%
> > air.tv.douyu.android 4257 4152 -2%
> >
> > ------------------
> > Benchmarks results
> >
> > Base kernel is v4.17.0-rc4-mm1
> > SPF is BASE + this series
> >
> > Kernbench:
> > ----------
> > Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
> > kernel (kernel is build 5 times):
> >
> > Average Half load -j 8
> > Run (std deviation)
> > BASE SPF
> > Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
> > User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
> > System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
> > Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
> > Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
> > Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
> >
> > Average Optimal load -j 16
> > Run (std deviation)
> > BASE SPF
> > Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
> > User Time 11064.8 (981.142) 11085 (990.897) 0.18%
> > System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
> > Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
> > Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
> > Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
> >
> >
> > During a run on the SPF, perf events were captured:
> > Performance counter stats for '../kernbench -M':
> > 526743764 faults
> > 210 spf
> > 3 pagefault:spf_vma_changed
> > 0 pagefault:spf_vma_noanon
> > 2278 pagefault:spf_vma_notsup
> > 0 pagefault:spf_vma_access
> > 0 pagefault:spf_pmd_changed
> >
> > Very few speculative page faults were recorded as most of the processes
> > involved are monothreaded (sounds that on this architecture some threads
> > were created during the kernel build processing).
> >
> > Here are the kerbench results on a 80 CPUs Power8 system:
> >
> > Average Half load -j 40
> > Run (std deviation)
> > BASE SPF
> > Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
> > User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
> > System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
> > Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
> > Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
> > Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
> >
> > Average Optimal load -j 80
> > Run (std deviation)
> > BASE SPF
> > Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
> > User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
> > System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
> > Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
> > Context Switches 223861 (138865) 225032 (139632) 0.52%
> > Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
> >
> > During a run on the SPF, perf events were captured:
> > Performance counter stats for '../kernbench -M':
> > 116730856 faults
> > 0 spf
> > 3 pagefault:spf_vma_changed
> > 0 pagefault:spf_vma_noanon
> > 476 pagefault:spf_vma_notsup
> > 0 pagefault:spf_vma_access
> > 0 pagefault:spf_pmd_changed
> >
> > Most of the processes involved are monothreaded so SPF is not activated but
> > there is no impact on the performance.
> >
> > Ebizzy:
> > -------
> > The test is counting the number of records per second it can manage, the
> > higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
> > consistent result I repeated the test 100 times and measure the average
> > result. The number is the record processes per second, the higher is the
> > best.
> >
> > BASE SPF delta
> > 16 CPUs x86 VM 742.57 1490.24 100.69%
> > 80 CPUs P8 node 13105.4 24174.23 84.46%
> >
> > Here are the performance counter read during a run on a 16 CPUs x86 VM:
> > Performance counter stats for './ebizzy -mTt 16':
> > 1706379 faults
> > 1674599 spf
> > 30588 pagefault:spf_vma_changed
> > 0 pagefault:spf_vma_noanon
> > 363 pagefault:spf_vma_notsup
> > 0 pagefault:spf_vma_access
> > 0 pagefault:spf_pmd_changed
> >
> > And the ones captured during a run on a 80 CPUs Power node:
> > Performance counter stats for './ebizzy -mTt 80':
> > 1874773 faults
> > 1461153 spf
> > 413293 pagefault:spf_vma_changed
> > 0 pagefault:spf_vma_noanon
> > 200 pagefault:spf_vma_notsup
> > 0 pagefault:spf_vma_access
> > 0 pagefault:spf_pmd_changed
> >
> > In ebizzy's case most of the page fault were handled in a speculative way,
> > leading the ebizzy performance boost.
> >
> > ------------------
> > Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
> > - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
> > and Minchan Kim, hopefully.
> > - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
> > __do_page_fault().
> > - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
> > instead
> > of aborting the speculative page fault handling. Dropping the now
> > useless
> > trace event pagefault:spf_pte_lock.
> > - No more try to reuse the fetched VMA during the speculative page fault
> > handling when retrying is needed. This adds a lot of complexity and
> > additional tests done didn't show a significant performance improvement.
> > - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
> >
> > [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
> > [2] https://patchwork.kernel.org/patch/9999687/
> >
> >
> > Laurent Dufour (20):
> > mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
> > x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> > powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> > mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
> > mm: make pte_unmap_same compatible with SPF
> > mm: introduce INIT_VMA()
> > mm: protect VMA modifications using VMA sequence count
> > mm: protect mremap() against SPF hanlder
> > mm: protect SPF handler against anon_vma changes
> > mm: cache some VMA fields in the vm_fault structure
> > mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
> > mm: introduce __lru_cache_add_active_or_unevictable
> > mm: introduce __vm_normal_page()
> > mm: introduce __page_add_new_anon_rmap()
> > mm: protect mm_rb tree with a rwlock
> > mm: adding speculative page fault failure trace events
> > perf: add a speculative page fault sw event
> > perf tools: add support for the SPF perf event
> > mm: add speculative page fault vmstats
> > powerpc/mm: add speculative page fault
> >
> > Mahendran Ganesh (2):
> > arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> > arm64/mm: add speculative page fault
> >
> > Peter Zijlstra (4):
> > mm: prepare for FAULT_FLAG_SPECULATIVE
> > mm: VMA sequence count
> > mm: provide speculative fault infrastructure
> > x86/mm: add speculative pagefault handling
> >
> > arch/arm64/Kconfig | 1 +
> > arch/arm64/mm/fault.c | 12 +
> > arch/powerpc/Kconfig | 1 +
> > arch/powerpc/mm/fault.c | 16 +
> > arch/x86/Kconfig | 1 +
> > arch/x86/mm/fault.c | 27 +-
> > fs/exec.c | 2 +-
> > fs/proc/task_mmu.c | 5 +-
> > fs/userfaultfd.c | 17 +-
> > include/linux/hugetlb_inline.h | 2 +-
> > include/linux/migrate.h | 4 +-
> > include/linux/mm.h | 136 +++++++-
> > include/linux/mm_types.h | 7 +
> > include/linux/pagemap.h | 4 +-
> > include/linux/rmap.h | 12 +-
> > include/linux/swap.h | 10 +-
> > include/linux/vm_event_item.h | 3 +
> > include/trace/events/pagefault.h | 80 +++++
> > include/uapi/linux/perf_event.h | 1 +
> > kernel/fork.c | 5 +-
> > mm/Kconfig | 22 ++
> > mm/huge_memory.c | 6 +-
> > mm/hugetlb.c | 2 +
> > mm/init-mm.c | 3 +
> > mm/internal.h | 20 ++
> > mm/khugepaged.c | 5 +
> > mm/madvise.c | 6 +-
> > mm/memory.c | 612 +++++++++++++++++++++++++++++-----
> > mm/mempolicy.c | 51 ++-
> > mm/migrate.c | 6 +-
> > mm/mlock.c | 13 +-
> > mm/mmap.c | 229 ++++++++++---
> > mm/mprotect.c | 4 +-
> > mm/mremap.c | 13 +
> > mm/nommu.c | 2 +-
> > mm/rmap.c | 5 +-
> > mm/swap.c | 6 +-
> > mm/swap_state.c | 8 +-
> > mm/vmstat.c | 5 +-
> > tools/include/uapi/linux/perf_event.h | 1 +
> > tools/perf/util/evsel.c | 1 +
> > tools/perf/util/parse-events.c | 4 +
> > tools/perf/util/parse-events.l | 1 +
> > tools/perf/util/python.c | 1 +
> > 44 files changed, 1161 insertions(+), 211 deletions(-)
> > create mode 100644 include/trace/events/pagefault.h
> >
> > --
> > 2.7.4
> >
> >
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* Re: [PATCH v11 00/26] Speculative page faults
2018-05-28 5:23 ` Song, HaiyanX
@ 2018-05-28 7:51 ` Laurent Dufour
2018-05-28 8:22 ` Haiyan Song
0 siblings, 1 reply; 46+ messages in thread
From: Laurent Dufour @ 2018-05-28 7:51 UTC (permalink / raw)
To: Song, HaiyanX, akpm, mhocko, peterz, kirill, ak, dave, jack,
Matthew Wilcox, khandual, aneesh.kumar, benh, mpe, paulus,
Thomas Gleixner, Ingo Molnar, hpa, Will Deacon,
Sergey Senozhatsky, sergey.senozhatsky.work, Andrea Arcangeli,
Alexei Starovoitov, Wang, Kemi, Daniel Jordan, David Rientjes,
Jerome Glisse, Ganesh Mahendran, Minchan Kim, Punit Agrawal,
vinayak menon, Yang Shi
Cc: linux-kernel, linux-mm, haren, npiggin, bsingharora, paulmck,
Tim Chen, linuxppc-dev, x86
On 28/05/2018 07:23, Song, HaiyanX wrote:
>
> Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
> tested on Intel 4s Skylake platform.
Hi,
Thanks for reporting this benchmark results, but you mentioned the "V9 patch
series" while responding to the v11 header series...
Were these tests done on v9 or v11 ?
Cheers,
Laurent.
>
> The regression result is sorted by the metric will-it-scale.per_thread_ops.
> Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
> Commit id:
> base commit: d55f34411b1b126429a823d06c3124c16283231f
> head commit: 0355322b3577eeab7669066df42c550a56801110
> Benchmark suite: will-it-scale
> Download link:
> https://github.com/antonblanchard/will-it-scale/tree/master/tests
> Metrics:
> will-it-scale.per_process_ops=processes/nr_cpu
> will-it-scale.per_thread_ops=threads/nr_cpu
> test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
> THP: enable / disable
> nr_task: 100%
>
> 1. Regressions:
> a) THP enabled:
> testcase base change head metric
> page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
> page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
> brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
> page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
> signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
>
> b) THP disabled:
> testcase base change head metric
> page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
> page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
> context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
> brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
> page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
> signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
>
> 2. Improvements:
> a) THP enabled:
> testcase base change head metric
> malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
> writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
> signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
>
> b) THP disabled:
> testcase base change head metric
> malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
> read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
> page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
> read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
> writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
> signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
>
> Notes: for above values in column "change", the higher value means that the related testcase result
> on head commit is better than that on base commit for this benchmark.
>
>
> Best regards
> Haiyan Song
>
> ________________________________________
> From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
> Sent: Thursday, May 17, 2018 7:06 PM
> To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
> Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
> Subject: [PATCH v11 00/26] Speculative page faults
>
> This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
> page fault without holding the mm semaphore [1].
>
> The idea is to try to handle user space page faults without holding the
> mmap_sem. This should allow better concurrency for massively threaded
> process since the page fault handler will not wait for other threads memory
> layout change to be done, assuming that this change is done in another part
> of the process's memory space. This type page fault is named speculative
> page fault. If the speculative page fault fails because of a concurrency is
> detected or because underlying PMD or PTE tables are not yet allocating, it
> is failing its processing and a classic page fault is then tried.
>
> The speculative page fault (SPF) has to look for the VMA matching the fault
> address without holding the mmap_sem, this is done by introducing a rwlock
> which protects the access to the mm_rb tree. Previously this was done using
> SRCU but it was introducing a lot of scheduling to process the VMA's
> freeing operation which was hitting the performance by 20% as reported by
> Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
> limiting the locking contention to these operations which are expected to
> be in a O(log n) order. In addition to ensure that the VMA is not freed in
> our back a reference count is added and 2 services (get_vma() and
> put_vma()) are introduced to handle the reference count. Once a VMA is
> fetched from the RB tree using get_vma(), it must be later freed using
> put_vma(). I can't see anymore the overhead I got while will-it-scale
> benchmark anymore.
>
> The VMA's attributes checked during the speculative page fault processing
> have to be protected against parallel changes. This is done by using a per
> VMA sequence lock. This sequence lock allows the speculative page fault
> handler to fast check for parallel changes in progress and to abort the
> speculative page fault in that case.
>
> Once the VMA has been found, the speculative page fault handler would check
> for the VMA's attributes to verify that the page fault has to be handled
> correctly or not. Thus, the VMA is protected through a sequence lock which
> allows fast detection of concurrent VMA changes. If such a change is
> detected, the speculative page fault is aborted and a *classic* page fault
> is tried. VMA sequence lockings are added when VMA attributes which are
> checked during the page fault are modified.
>
> When the PTE is fetched, the VMA is checked to see if it has been changed,
> so once the page table is locked, the VMA is valid, so any other changes
> leading to touching this PTE will need to lock the page table, so no
> parallel change is possible at this time.
>
> The locking of the PTE is done with interrupts disabled, this allows
> checking for the PMD to ensure that there is not an ongoing collapsing
> operation. Since khugepaged is firstly set the PMD to pmd_none and then is
> waiting for the other CPU to have caught the IPI interrupt, if the pmd is
> valid at the time the PTE is locked, we have the guarantee that the
> collapsing operation will have to wait on the PTE lock to move forward.
> This allows the SPF handler to map the PTE safely. If the PMD value is
> different from the one recorded at the beginning of the SPF operation, the
> classic page fault handler will be called to handle the operation while
> holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
> the lock is done using spin_trylock() to avoid dead lock when handling a
> page fault while a TLB invalidate is requested by another CPU holding the
> PTE.
>
> In pseudo code, this could be seen as:
> speculative_page_fault()
> {
> vma = get_vma()
> check vma sequence count
> check vma's support
> disable interrupt
> check pgd,p4d,...,pte
> save pmd and pte in vmf
> save vma sequence counter in vmf
> enable interrupt
> check vma sequence count
> handle_pte_fault(vma)
> ..
> page = alloc_page()
> pte_map_lock()
> disable interrupt
> abort if sequence counter has changed
> abort if pmd or pte has changed
> pte map and lock
> enable interrupt
> if abort
> free page
> abort
> ...
> }
>
> arch_fault_handler()
> {
> if (speculative_page_fault(&vma))
> goto done
> again:
> lock(mmap_sem)
> vma = find_vma();
> handle_pte_fault(vma);
> if retry
> unlock(mmap_sem)
> goto again;
> done:
> handle fault error
> }
>
> Support for THP is not done because when checking for the PMD, we can be
> confused by an in progress collapsing operation done by khugepaged. The
> issue is that pmd_none() could be true either if the PMD is not already
> populated or if the underlying PTE are in the way to be collapsed. So we
> cannot safely allocate a PMD if pmd_none() is true.
>
> This series add a new software performance event named 'speculative-faults'
> or 'spf'. It counts the number of successful page fault event handled
> speculatively. When recording 'faults,spf' events, the faults one is
> counting the total number of page fault events while 'spf' is only counting
> the part of the faults processed speculatively.
>
> There are some trace events introduced by this series. They allow
> identifying why the page faults were not processed speculatively. This
> doesn't take in account the faults generated by a monothreaded process
> which directly processed while holding the mmap_sem. This trace events are
> grouped in a system named 'pagefault', they are:
> - pagefault:spf_vma_changed : if the VMA has been changed in our back
> - pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
> - pagefault:spf_vma_notsup : the VMA's type is not supported
> - pagefault:spf_vma_access : the VMA's access right are not respected
> - pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
> back.
>
> To record all the related events, the easier is to run perf with the
> following arguments :
> $ perf stat -e 'faults,spf,pagefault:*' <command>
>
> There is also a dedicated vmstat counter showing the number of successful
> page fault handled speculatively. I can be seen this way:
> $ grep speculative_pgfault /proc/vmstat
>
> This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
> on x86, PowerPC and arm64.
>
> ---------------------
> Real Workload results
>
> As mentioned in previous email, we did non official runs using a "popular
> in memory multithreaded database product" on 176 cores SMT8 Power system
> which showed a 30% improvements in the number of transaction processed per
> second. This run has been done on the v6 series, but changes introduced in
> this new version should not impact the performance boost seen.
>
> Here are the perf data captured during 2 of these runs on top of the v8
> series:
> vanilla spf
> faults 89.418 101.364 +13%
> spf n/a 97.989
>
> With the SPF kernel, most of the page fault were processed in a speculative
> way.
>
> Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
> it a try on an android device. He reported that the application launch time
> was improved in average by 6%, and for large applications (~100 threads) by
> 20%.
>
> Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
> MSM845 (8 cores) with 6GB (the less is better):
>
> Application 4.9 4.9+spf delta
> com.tencent.mm 416 389 -7%
> com.eg.android.AlipayGphone 1135 986 -13%
> com.tencent.mtt 455 454 0%
> com.qqgame.hlddz 1497 1409 -6%
> com.autonavi.minimap 711 701 -1%
> com.tencent.tmgp.sgame 788 748 -5%
> com.immomo.momo 501 487 -3%
> com.tencent.peng 2145 2112 -2%
> com.smile.gifmaker 491 461 -6%
> com.baidu.BaiduMap 479 366 -23%
> com.taobao.taobao 1341 1198 -11%
> com.baidu.searchbox 333 314 -6%
> com.tencent.mobileqq 394 384 -3%
> com.sina.weibo 907 906 0%
> com.youku.phone 816 731 -11%
> com.happyelements.AndroidAnimal.qq 763 717 -6%
> com.UCMobile 415 411 -1%
> com.tencent.tmgp.ak 1464 1431 -2%
> com.tencent.qqmusic 336 329 -2%
> com.sankuai.meituan 1661 1302 -22%
> com.netease.cloudmusic 1193 1200 1%
> air.tv.douyu.android 4257 4152 -2%
>
> ------------------
> Benchmarks results
>
> Base kernel is v4.17.0-rc4-mm1
> SPF is BASE + this series
>
> Kernbench:
> ----------
> Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
> kernel (kernel is build 5 times):
>
> Average Half load -j 8
> Run (std deviation)
> BASE SPF
> Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
> User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
> System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
> Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
> Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
> Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
>
> Average Optimal load -j 16
> Run (std deviation)
> BASE SPF
> Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
> User Time 11064.8 (981.142) 11085 (990.897) 0.18%
> System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
> Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
> Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
> Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
>
>
> During a run on the SPF, perf events were captured:
> Performance counter stats for '../kernbench -M':
> 526743764 faults
> 210 spf
> 3 pagefault:spf_vma_changed
> 0 pagefault:spf_vma_noanon
> 2278 pagefault:spf_vma_notsup
> 0 pagefault:spf_vma_access
> 0 pagefault:spf_pmd_changed
>
> Very few speculative page faults were recorded as most of the processes
> involved are monothreaded (sounds that on this architecture some threads
> were created during the kernel build processing).
>
> Here are the kerbench results on a 80 CPUs Power8 system:
>
> Average Half load -j 40
> Run (std deviation)
> BASE SPF
> Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
> User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
> System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
> Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
> Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
> Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
>
> Average Optimal load -j 80
> Run (std deviation)
> BASE SPF
> Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
> User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
> System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
> Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
> Context Switches 223861 (138865) 225032 (139632) 0.52%
> Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
>
> During a run on the SPF, perf events were captured:
> Performance counter stats for '../kernbench -M':
> 116730856 faults
> 0 spf
> 3 pagefault:spf_vma_changed
> 0 pagefault:spf_vma_noanon
> 476 pagefault:spf_vma_notsup
> 0 pagefault:spf_vma_access
> 0 pagefault:spf_pmd_changed
>
> Most of the processes involved are monothreaded so SPF is not activated but
> there is no impact on the performance.
>
> Ebizzy:
> -------
> The test is counting the number of records per second it can manage, the
> higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
> consistent result I repeated the test 100 times and measure the average
> result. The number is the record processes per second, the higher is the
> best.
>
> BASE SPF delta
> 16 CPUs x86 VM 742.57 1490.24 100.69%
> 80 CPUs P8 node 13105.4 24174.23 84.46%
>
> Here are the performance counter read during a run on a 16 CPUs x86 VM:
> Performance counter stats for './ebizzy -mTt 16':
> 1706379 faults
> 1674599 spf
> 30588 pagefault:spf_vma_changed
> 0 pagefault:spf_vma_noanon
> 363 pagefault:spf_vma_notsup
> 0 pagefault:spf_vma_access
> 0 pagefault:spf_pmd_changed
>
> And the ones captured during a run on a 80 CPUs Power node:
> Performance counter stats for './ebizzy -mTt 80':
> 1874773 faults
> 1461153 spf
> 413293 pagefault:spf_vma_changed
> 0 pagefault:spf_vma_noanon
> 200 pagefault:spf_vma_notsup
> 0 pagefault:spf_vma_access
> 0 pagefault:spf_pmd_changed
>
> In ebizzy's case most of the page fault were handled in a speculative way,
> leading the ebizzy performance boost.
>
> ------------------
> Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
> - Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
> and Minchan Kim, hopefully.
> - Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
> __do_page_fault().
> - Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
> instead
> of aborting the speculative page fault handling. Dropping the now
> useless
> trace event pagefault:spf_pte_lock.
> - No more try to reuse the fetched VMA during the speculative page fault
> handling when retrying is needed. This adds a lot of complexity and
> additional tests done didn't show a significant performance improvement.
> - Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
>
> [1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
> [2] https://patchwork.kernel.org/patch/9999687/
>
>
> Laurent Dufour (20):
> mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
> x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
> mm: make pte_unmap_same compatible with SPF
> mm: introduce INIT_VMA()
> mm: protect VMA modifications using VMA sequence count
> mm: protect mremap() against SPF hanlder
> mm: protect SPF handler against anon_vma changes
> mm: cache some VMA fields in the vm_fault structure
> mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
> mm: introduce __lru_cache_add_active_or_unevictable
> mm: introduce __vm_normal_page()
> mm: introduce __page_add_new_anon_rmap()
> mm: protect mm_rb tree with a rwlock
> mm: adding speculative page fault failure trace events
> perf: add a speculative page fault sw event
> perf tools: add support for the SPF perf event
> mm: add speculative page fault vmstats
> powerpc/mm: add speculative page fault
>
> Mahendran Ganesh (2):
> arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
> arm64/mm: add speculative page fault
>
> Peter Zijlstra (4):
> mm: prepare for FAULT_FLAG_SPECULATIVE
> mm: VMA sequence count
> mm: provide speculative fault infrastructure
> x86/mm: add speculative pagefault handling
>
> arch/arm64/Kconfig | 1 +
> arch/arm64/mm/fault.c | 12 +
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/mm/fault.c | 16 +
> arch/x86/Kconfig | 1 +
> arch/x86/mm/fault.c | 27 +-
> fs/exec.c | 2 +-
> fs/proc/task_mmu.c | 5 +-
> fs/userfaultfd.c | 17 +-
> include/linux/hugetlb_inline.h | 2 +-
> include/linux/migrate.h | 4 +-
> include/linux/mm.h | 136 +++++++-
> include/linux/mm_types.h | 7 +
> include/linux/pagemap.h | 4 +-
> include/linux/rmap.h | 12 +-
> include/linux/swap.h | 10 +-
> include/linux/vm_event_item.h | 3 +
> include/trace/events/pagefault.h | 80 +++++
> include/uapi/linux/perf_event.h | 1 +
> kernel/fork.c | 5 +-
> mm/Kconfig | 22 ++
> mm/huge_memory.c | 6 +-
> mm/hugetlb.c | 2 +
> mm/init-mm.c | 3 +
> mm/internal.h | 20 ++
> mm/khugepaged.c | 5 +
> mm/madvise.c | 6 +-
> mm/memory.c | 612 +++++++++++++++++++++++++++++-----
> mm/mempolicy.c | 51 ++-
> mm/migrate.c | 6 +-
> mm/mlock.c | 13 +-
> mm/mmap.c | 229 ++++++++++---
> mm/mprotect.c | 4 +-
> mm/mremap.c | 13 +
> mm/nommu.c | 2 +-
> mm/rmap.c | 5 +-
> mm/swap.c | 6 +-
> mm/swap_state.c | 8 +-
> mm/vmstat.c | 5 +-
> tools/include/uapi/linux/perf_event.h | 1 +
> tools/perf/util/evsel.c | 1 +
> tools/perf/util/parse-events.c | 4 +
> tools/perf/util/parse-events.l | 1 +
> tools/perf/util/python.c | 1 +
> 44 files changed, 1161 insertions(+), 211 deletions(-)
> create mode 100644 include/trace/events/pagefault.h
>
> --
> 2.7.4
>
>
^ permalink raw reply [flat|nested] 46+ messages in thread
* RE: [PATCH v11 00/26] Speculative page faults
2018-05-17 11:06 Laurent Dufour
@ 2018-05-28 5:23 ` Song, HaiyanX
2018-05-28 7:51 ` Laurent Dufour
2018-11-05 10:42 ` Balbir Singh
1 sibling, 1 reply; 46+ messages in thread
From: Song, HaiyanX @ 2018-05-28 5:23 UTC (permalink / raw)
To: Laurent Dufour, akpm, mhocko, peterz, kirill, ak, dave, jack,
Matthew Wilcox, khandual, aneesh.kumar, benh, mpe, paulus,
Thomas Gleixner, Ingo Molnar, hpa, Will Deacon,
Sergey Senozhatsky, sergey.senozhatsky.work, Andrea Arcangeli,
Alexei Starovoitov, Wang, Kemi, Daniel Jordan, David Rientjes,
Jerome Glisse, Ganesh Mahendran, Minchan Kim, Punit Agrawal,
vinayak menon, Yang Shi
Cc: linux-kernel, linux-mm, haren, npiggin, bsingharora, paulmck,
Tim Chen, linuxppc-dev, x86
Some regression and improvements is found by LKP-tools(linux kernel performance) on V9 patch series
tested on Intel 4s Skylake platform.
The regression result is sorted by the metric will-it-scale.per_thread_ops.
Branch: Laurent-Dufour/Speculative-page-faults/20180316-151833 (V9 patch series)
Commit id:
base commit: d55f34411b1b126429a823d06c3124c16283231f
head commit: 0355322b3577eeab7669066df42c550a56801110
Benchmark suite: will-it-scale
Download link:
https://github.com/antonblanchard/will-it-scale/tree/master/tests
Metrics:
will-it-scale.per_process_ops=processes/nr_cpu
will-it-scale.per_thread_ops=threads/nr_cpu
test box: lkp-skl-4sp1(nr_cpu=192,memory=768G)
THP: enable / disable
nr_task: 100%
1. Regressions:
a) THP enabled:
testcase base change head metric
page_fault3/ enable THP 10092 -17.5% 8323 will-it-scale.per_thread_ops
page_fault2/ enable THP 8300 -17.2% 6869 will-it-scale.per_thread_ops
brk1/ enable THP 957.67 -7.6% 885 will-it-scale.per_thread_ops
page_fault3/ enable THP 172821 -5.3% 163692 will-it-scale.per_process_ops
signal1/ enable THP 9125 -3.2% 8834 will-it-scale.per_process_ops
b) THP disabled:
testcase base change head metric
page_fault3/ disable THP 10107 -19.1% 8180 will-it-scale.per_thread_ops
page_fault2/ disable THP 8432 -17.8% 6931 will-it-scale.per_thread_ops
context_switch1/ disable THP 215389 -6.8% 200776 will-it-scale.per_thread_ops
brk1/ disable THP 939.67 -6.6% 877.33 will-it-scale.per_thread_ops
page_fault3/ disable THP 173145 -4.7% 165064 will-it-scale.per_process_ops
signal1/ disable THP 9162 -3.9% 8802 will-it-scale.per_process_ops
2. Improvements:
a) THP enabled:
testcase base change head metric
malloc1/ enable THP 66.33 +469.8% 383.67 will-it-scale.per_thread_ops
writeseek3/ enable THP 2531 +4.5% 2646 will-it-scale.per_thread_ops
signal1/ enable THP 989.33 +2.8% 1016 will-it-scale.per_thread_ops
b) THP disabled:
testcase base change head metric
malloc1/ disable THP 90.33 +417.3% 467.33 will-it-scale.per_thread_ops
read2/ disable THP 58934 +39.2% 82060 will-it-scale.per_thread_ops
page_fault1/ disable THP 8607 +36.4% 11736 will-it-scale.per_thread_ops
read1/ disable THP 314063 +12.7% 353934 will-it-scale.per_thread_ops
writeseek3/ disable THP 2452 +12.5% 2759 will-it-scale.per_thread_ops
signal1/ disable THP 971.33 +5.5% 1024 will-it-scale.per_thread_ops
Notes: for above values in column "change", the higher value means that the related testcase result
on head commit is better than that on base commit for this benchmark.
Best regards
Haiyan Song
________________________________________
From: owner-linux-mm@kvack.org [owner-linux-mm@kvack.org] on behalf of Laurent Dufour [ldufour@linux.vnet.ibm.com]
Sent: Thursday, May 17, 2018 7:06 PM
To: akpm@linux-foundation.org; mhocko@kernel.org; peterz@infradead.org; kirill@shutemov.name; ak@linux.intel.com; dave@stgolabs.net; jack@suse.cz; Matthew Wilcox; khandual@linux.vnet.ibm.com; aneesh.kumar@linux.vnet.ibm.com; benh@kernel.crashing.org; mpe@ellerman.id.au; paulus@samba.org; Thomas Gleixner; Ingo Molnar; hpa@zytor.com; Will Deacon; Sergey Senozhatsky; sergey.senozhatsky.work@gmail.com; Andrea Arcangeli; Alexei Starovoitov; Wang, Kemi; Daniel Jordan; David Rientjes; Jerome Glisse; Ganesh Mahendran; Minchan Kim; Punit Agrawal; vinayak menon; Yang Shi
Cc: linux-kernel@vger.kernel.org; linux-mm@kvack.org; haren@linux.vnet.ibm.com; npiggin@gmail.com; bsingharora@gmail.com; paulmck@linux.vnet.ibm.com; Tim Chen; linuxppc-dev@lists.ozlabs.org; x86@kernel.org
Subject: [PATCH v11 00/26] Speculative page faults
This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
page fault without holding the mm semaphore [1].
The idea is to try to handle user space page faults without holding the
mmap_sem. This should allow better concurrency for massively threaded
process since the page fault handler will not wait for other threads memory
layout change to be done, assuming that this change is done in another part
of the process's memory space. This type page fault is named speculative
page fault. If the speculative page fault fails because of a concurrency is
detected or because underlying PMD or PTE tables are not yet allocating, it
is failing its processing and a classic page fault is then tried.
The speculative page fault (SPF) has to look for the VMA matching the fault
address without holding the mmap_sem, this is done by introducing a rwlock
which protects the access to the mm_rb tree. Previously this was done using
SRCU but it was introducing a lot of scheduling to process the VMA's
freeing operation which was hitting the performance by 20% as reported by
Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
limiting the locking contention to these operations which are expected to
be in a O(log n) order. In addition to ensure that the VMA is not freed in
our back a reference count is added and 2 services (get_vma() and
put_vma()) are introduced to handle the reference count. Once a VMA is
fetched from the RB tree using get_vma(), it must be later freed using
put_vma(). I can't see anymore the overhead I got while will-it-scale
benchmark anymore.
The VMA's attributes checked during the speculative page fault processing
have to be protected against parallel changes. This is done by using a per
VMA sequence lock. This sequence lock allows the speculative page fault
handler to fast check for parallel changes in progress and to abort the
speculative page fault in that case.
Once the VMA has been found, the speculative page fault handler would check
for the VMA's attributes to verify that the page fault has to be handled
correctly or not. Thus, the VMA is protected through a sequence lock which
allows fast detection of concurrent VMA changes. If such a change is
detected, the speculative page fault is aborted and a *classic* page fault
is tried. VMA sequence lockings are added when VMA attributes which are
checked during the page fault are modified.
When the PTE is fetched, the VMA is checked to see if it has been changed,
so once the page table is locked, the VMA is valid, so any other changes
leading to touching this PTE will need to lock the page table, so no
parallel change is possible at this time.
The locking of the PTE is done with interrupts disabled, this allows
checking for the PMD to ensure that there is not an ongoing collapsing
operation. Since khugepaged is firstly set the PMD to pmd_none and then is
waiting for the other CPU to have caught the IPI interrupt, if the pmd is
valid at the time the PTE is locked, we have the guarantee that the
collapsing operation will have to wait on the PTE lock to move forward.
This allows the SPF handler to map the PTE safely. If the PMD value is
different from the one recorded at the beginning of the SPF operation, the
classic page fault handler will be called to handle the operation while
holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
the lock is done using spin_trylock() to avoid dead lock when handling a
page fault while a TLB invalidate is requested by another CPU holding the
PTE.
In pseudo code, this could be seen as:
speculative_page_fault()
{
vma = get_vma()
check vma sequence count
check vma's support
disable interrupt
check pgd,p4d,...,pte
save pmd and pte in vmf
save vma sequence counter in vmf
enable interrupt
check vma sequence count
handle_pte_fault(vma)
..
page = alloc_page()
pte_map_lock()
disable interrupt
abort if sequence counter has changed
abort if pmd or pte has changed
pte map and lock
enable interrupt
if abort
free page
abort
...
}
arch_fault_handler()
{
if (speculative_page_fault(&vma))
goto done
again:
lock(mmap_sem)
vma = find_vma();
handle_pte_fault(vma);
if retry
unlock(mmap_sem)
goto again;
done:
handle fault error
}
Support for THP is not done because when checking for the PMD, we can be
confused by an in progress collapsing operation done by khugepaged. The
issue is that pmd_none() could be true either if the PMD is not already
populated or if the underlying PTE are in the way to be collapsed. So we
cannot safely allocate a PMD if pmd_none() is true.
This series add a new software performance event named 'speculative-faults'
or 'spf'. It counts the number of successful page fault event handled
speculatively. When recording 'faults,spf' events, the faults one is
counting the total number of page fault events while 'spf' is only counting
the part of the faults processed speculatively.
There are some trace events introduced by this series. They allow
identifying why the page faults were not processed speculatively. This
doesn't take in account the faults generated by a monothreaded process
which directly processed while holding the mmap_sem. This trace events are
grouped in a system named 'pagefault', they are:
- pagefault:spf_vma_changed : if the VMA has been changed in our back
- pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
- pagefault:spf_vma_notsup : the VMA's type is not supported
- pagefault:spf_vma_access : the VMA's access right are not respected
- pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
back.
To record all the related events, the easier is to run perf with the
following arguments :
$ perf stat -e 'faults,spf,pagefault:*' <command>
There is also a dedicated vmstat counter showing the number of successful
page fault handled speculatively. I can be seen this way:
$ grep speculative_pgfault /proc/vmstat
This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
on x86, PowerPC and arm64.
---------------------
Real Workload results
As mentioned in previous email, we did non official runs using a "popular
in memory multithreaded database product" on 176 cores SMT8 Power system
which showed a 30% improvements in the number of transaction processed per
second. This run has been done on the v6 series, but changes introduced in
this new version should not impact the performance boost seen.
Here are the perf data captured during 2 of these runs on top of the v8
series:
vanilla spf
faults 89.418 101.364 +13%
spf n/a 97.989
With the SPF kernel, most of the page fault were processed in a speculative
way.
Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
it a try on an android device. He reported that the application launch time
was improved in average by 6%, and for large applications (~100 threads) by
20%.
Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
MSM845 (8 cores) with 6GB (the less is better):
Application 4.9 4.9+spf delta
com.tencent.mm 416 389 -7%
com.eg.android.AlipayGphone 1135 986 -13%
com.tencent.mtt 455 454 0%
com.qqgame.hlddz 1497 1409 -6%
com.autonavi.minimap 711 701 -1%
com.tencent.tmgp.sgame 788 748 -5%
com.immomo.momo 501 487 -3%
com.tencent.peng 2145 2112 -2%
com.smile.gifmaker 491 461 -6%
com.baidu.BaiduMap 479 366 -23%
com.taobao.taobao 1341 1198 -11%
com.baidu.searchbox 333 314 -6%
com.tencent.mobileqq 394 384 -3%
com.sina.weibo 907 906 0%
com.youku.phone 816 731 -11%
com.happyelements.AndroidAnimal.qq 763 717 -6%
com.UCMobile 415 411 -1%
com.tencent.tmgp.ak 1464 1431 -2%
com.tencent.qqmusic 336 329 -2%
com.sankuai.meituan 1661 1302 -22%
com.netease.cloudmusic 1193 1200 1%
air.tv.douyu.android 4257 4152 -2%
------------------
Benchmarks results
Base kernel is v4.17.0-rc4-mm1
SPF is BASE + this series
Kernbench:
----------
Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
kernel (kernel is build 5 times):
Average Half load -j 8
Run (std deviation)
BASE SPF
Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
Average Optimal load -j 16
Run (std deviation)
BASE SPF
Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
User Time 11064.8 (981.142) 11085 (990.897) 0.18%
System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
During a run on the SPF, perf events were captured:
Performance counter stats for '../kernbench -M':
526743764 faults
210 spf
3 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
2278 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
Very few speculative page faults were recorded as most of the processes
involved are monothreaded (sounds that on this architecture some threads
were created during the kernel build processing).
Here are the kerbench results on a 80 CPUs Power8 system:
Average Half load -j 40
Run (std deviation)
BASE SPF
Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
Average Optimal load -j 80
Run (std deviation)
BASE SPF
Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
Context Switches 223861 (138865) 225032 (139632) 0.52%
Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
During a run on the SPF, perf events were captured:
Performance counter stats for '../kernbench -M':
116730856 faults
0 spf
3 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
476 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
Most of the processes involved are monothreaded so SPF is not activated but
there is no impact on the performance.
Ebizzy:
-------
The test is counting the number of records per second it can manage, the
higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
consistent result I repeated the test 100 times and measure the average
result. The number is the record processes per second, the higher is the
best.
BASE SPF delta
16 CPUs x86 VM 742.57 1490.24 100.69%
80 CPUs P8 node 13105.4 24174.23 84.46%
Here are the performance counter read during a run on a 16 CPUs x86 VM:
Performance counter stats for './ebizzy -mTt 16':
1706379 faults
1674599 spf
30588 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
363 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
And the ones captured during a run on a 80 CPUs Power node:
Performance counter stats for './ebizzy -mTt 80':
1874773 faults
1461153 spf
413293 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
200 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
In ebizzy's case most of the page fault were handled in a speculative way,
leading the ebizzy performance boost.
------------------
Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
- Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
and Minchan Kim, hopefully.
- Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
__do_page_fault().
- Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
instead
of aborting the speculative page fault handling. Dropping the now
useless
trace event pagefault:spf_pte_lock.
- No more try to reuse the fetched VMA during the speculative page fault
handling when retrying is needed. This adds a lot of complexity and
additional tests done didn't show a significant performance improvement.
- Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
[1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
[2] https://patchwork.kernel.org/patch/9999687/
Laurent Dufour (20):
mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
mm: make pte_unmap_same compatible with SPF
mm: introduce INIT_VMA()
mm: protect VMA modifications using VMA sequence count
mm: protect mremap() against SPF hanlder
mm: protect SPF handler against anon_vma changes
mm: cache some VMA fields in the vm_fault structure
mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
mm: introduce __lru_cache_add_active_or_unevictable
mm: introduce __vm_normal_page()
mm: introduce __page_add_new_anon_rmap()
mm: protect mm_rb tree with a rwlock
mm: adding speculative page fault failure trace events
perf: add a speculative page fault sw event
perf tools: add support for the SPF perf event
mm: add speculative page fault vmstats
powerpc/mm: add speculative page fault
Mahendran Ganesh (2):
arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
arm64/mm: add speculative page fault
Peter Zijlstra (4):
mm: prepare for FAULT_FLAG_SPECULATIVE
mm: VMA sequence count
mm: provide speculative fault infrastructure
x86/mm: add speculative pagefault handling
arch/arm64/Kconfig | 1 +
arch/arm64/mm/fault.c | 12 +
arch/powerpc/Kconfig | 1 +
arch/powerpc/mm/fault.c | 16 +
arch/x86/Kconfig | 1 +
arch/x86/mm/fault.c | 27 +-
fs/exec.c | 2 +-
fs/proc/task_mmu.c | 5 +-
fs/userfaultfd.c | 17 +-
include/linux/hugetlb_inline.h | 2 +-
include/linux/migrate.h | 4 +-
include/linux/mm.h | 136 +++++++-
include/linux/mm_types.h | 7 +
include/linux/pagemap.h | 4 +-
include/linux/rmap.h | 12 +-
include/linux/swap.h | 10 +-
include/linux/vm_event_item.h | 3 +
include/trace/events/pagefault.h | 80 +++++
include/uapi/linux/perf_event.h | 1 +
kernel/fork.c | 5 +-
mm/Kconfig | 22 ++
mm/huge_memory.c | 6 +-
mm/hugetlb.c | 2 +
mm/init-mm.c | 3 +
mm/internal.h | 20 ++
mm/khugepaged.c | 5 +
mm/madvise.c | 6 +-
mm/memory.c | 612 +++++++++++++++++++++++++++++-----
mm/mempolicy.c | 51 ++-
mm/migrate.c | 6 +-
mm/mlock.c | 13 +-
mm/mmap.c | 229 ++++++++++---
mm/mprotect.c | 4 +-
mm/mremap.c | 13 +
mm/nommu.c | 2 +-
mm/rmap.c | 5 +-
mm/swap.c | 6 +-
mm/swap_state.c | 8 +-
mm/vmstat.c | 5 +-
tools/include/uapi/linux/perf_event.h | 1 +
tools/perf/util/evsel.c | 1 +
tools/perf/util/parse-events.c | 4 +
tools/perf/util/parse-events.l | 1 +
tools/perf/util/python.c | 1 +
44 files changed, 1161 insertions(+), 211 deletions(-)
create mode 100644 include/trace/events/pagefault.h
--
2.7.4
^ permalink raw reply [flat|nested] 46+ messages in thread
* [PATCH v11 00/26] Speculative page faults
@ 2018-05-17 11:06 Laurent Dufour
2018-05-28 5:23 ` Song, HaiyanX
2018-11-05 10:42 ` Balbir Singh
0 siblings, 2 replies; 46+ messages in thread
From: Laurent Dufour @ 2018-05-17 11:06 UTC (permalink / raw)
To: akpm, mhocko, peterz, kirill, ak, dave, jack, Matthew Wilcox,
khandual, aneesh.kumar, benh, mpe, paulus, Thomas Gleixner,
Ingo Molnar, hpa, Will Deacon, Sergey Senozhatsky,
sergey.senozhatsky.work, Andrea Arcangeli, Alexei Starovoitov,
kemi.wang, Daniel Jordan, David Rientjes, Jerome Glisse,
Ganesh Mahendran, Minchan Kim, Punit Agrawal, vinayak menon,
Yang Shi
Cc: linux-kernel, linux-mm, haren, npiggin, bsingharora, paulmck,
Tim Chen, linuxppc-dev, x86
This is a port on kernel 4.17 of the work done by Peter Zijlstra to handle
page fault without holding the mm semaphore [1].
The idea is to try to handle user space page faults without holding the
mmap_sem. This should allow better concurrency for massively threaded
process since the page fault handler will not wait for other threads memory
layout change to be done, assuming that this change is done in another part
of the process's memory space. This type page fault is named speculative
page fault. If the speculative page fault fails because of a concurrency is
detected or because underlying PMD or PTE tables are not yet allocating, it
is failing its processing and a classic page fault is then tried.
The speculative page fault (SPF) has to look for the VMA matching the fault
address without holding the mmap_sem, this is done by introducing a rwlock
which protects the access to the mm_rb tree. Previously this was done using
SRCU but it was introducing a lot of scheduling to process the VMA's
freeing operation which was hitting the performance by 20% as reported by
Kemi Wang [2]. Using a rwlock to protect access to the mm_rb tree is
limiting the locking contention to these operations which are expected to
be in a O(log n) order. In addition to ensure that the VMA is not freed in
our back a reference count is added and 2 services (get_vma() and
put_vma()) are introduced to handle the reference count. Once a VMA is
fetched from the RB tree using get_vma(), it must be later freed using
put_vma(). I can't see anymore the overhead I got while will-it-scale
benchmark anymore.
The VMA's attributes checked during the speculative page fault processing
have to be protected against parallel changes. This is done by using a per
VMA sequence lock. This sequence lock allows the speculative page fault
handler to fast check for parallel changes in progress and to abort the
speculative page fault in that case.
Once the VMA has been found, the speculative page fault handler would check
for the VMA's attributes to verify that the page fault has to be handled
correctly or not. Thus, the VMA is protected through a sequence lock which
allows fast detection of concurrent VMA changes. If such a change is
detected, the speculative page fault is aborted and a *classic* page fault
is tried. VMA sequence lockings are added when VMA attributes which are
checked during the page fault are modified.
When the PTE is fetched, the VMA is checked to see if it has been changed,
so once the page table is locked, the VMA is valid, so any other changes
leading to touching this PTE will need to lock the page table, so no
parallel change is possible at this time.
The locking of the PTE is done with interrupts disabled, this allows
checking for the PMD to ensure that there is not an ongoing collapsing
operation. Since khugepaged is firstly set the PMD to pmd_none and then is
waiting for the other CPU to have caught the IPI interrupt, if the pmd is
valid at the time the PTE is locked, we have the guarantee that the
collapsing operation will have to wait on the PTE lock to move forward.
This allows the SPF handler to map the PTE safely. If the PMD value is
different from the one recorded at the beginning of the SPF operation, the
classic page fault handler will be called to handle the operation while
holding the mmap_sem. As the PTE lock is done with the interrupts disabled,
the lock is done using spin_trylock() to avoid dead lock when handling a
page fault while a TLB invalidate is requested by another CPU holding the
PTE.
In pseudo code, this could be seen as:
speculative_page_fault()
{
vma = get_vma()
check vma sequence count
check vma's support
disable interrupt
check pgd,p4d,...,pte
save pmd and pte in vmf
save vma sequence counter in vmf
enable interrupt
check vma sequence count
handle_pte_fault(vma)
..
page = alloc_page()
pte_map_lock()
disable interrupt
abort if sequence counter has changed
abort if pmd or pte has changed
pte map and lock
enable interrupt
if abort
free page
abort
...
}
arch_fault_handler()
{
if (speculative_page_fault(&vma))
goto done
again:
lock(mmap_sem)
vma = find_vma();
handle_pte_fault(vma);
if retry
unlock(mmap_sem)
goto again;
done:
handle fault error
}
Support for THP is not done because when checking for the PMD, we can be
confused by an in progress collapsing operation done by khugepaged. The
issue is that pmd_none() could be true either if the PMD is not already
populated or if the underlying PTE are in the way to be collapsed. So we
cannot safely allocate a PMD if pmd_none() is true.
This series add a new software performance event named 'speculative-faults'
or 'spf'. It counts the number of successful page fault event handled
speculatively. When recording 'faults,spf' events, the faults one is
counting the total number of page fault events while 'spf' is only counting
the part of the faults processed speculatively.
There are some trace events introduced by this series. They allow
identifying why the page faults were not processed speculatively. This
doesn't take in account the faults generated by a monothreaded process
which directly processed while holding the mmap_sem. This trace events are
grouped in a system named 'pagefault', they are:
- pagefault:spf_vma_changed : if the VMA has been changed in our back
- pagefault:spf_vma_noanon : the vma->anon_vma field was not yet set.
- pagefault:spf_vma_notsup : the VMA's type is not supported
- pagefault:spf_vma_access : the VMA's access right are not respected
- pagefault:spf_pmd_changed : the upper PMD pointer has changed in our
back.
To record all the related events, the easier is to run perf with the
following arguments :
$ perf stat -e 'faults,spf,pagefault:*' <command>
There is also a dedicated vmstat counter showing the number of successful
page fault handled speculatively. I can be seen this way:
$ grep speculative_pgfault /proc/vmstat
This series builds on top of v4.16-mmotm-2018-04-13-17-28 and is functional
on x86, PowerPC and arm64.
---------------------
Real Workload results
As mentioned in previous email, we did non official runs using a "popular
in memory multithreaded database product" on 176 cores SMT8 Power system
which showed a 30% improvements in the number of transaction processed per
second. This run has been done on the v6 series, but changes introduced in
this new version should not impact the performance boost seen.
Here are the perf data captured during 2 of these runs on top of the v8
series:
vanilla spf
faults 89.418 101.364 +13%
spf n/a 97.989
With the SPF kernel, most of the page fault were processed in a speculative
way.
Ganesh Mahendran had backported the series on top of a 4.9 kernel and gave
it a try on an android device. He reported that the application launch time
was improved in average by 6%, and for large applications (~100 threads) by
20%.
Here are the launch time Ganesh mesured on Android 8.0 on top of a Qcom
MSM845 (8 cores) with 6GB (the less is better):
Application 4.9 4.9+spf delta
com.tencent.mm 416 389 -7%
com.eg.android.AlipayGphone 1135 986 -13%
com.tencent.mtt 455 454 0%
com.qqgame.hlddz 1497 1409 -6%
com.autonavi.minimap 711 701 -1%
com.tencent.tmgp.sgame 788 748 -5%
com.immomo.momo 501 487 -3%
com.tencent.peng 2145 2112 -2%
com.smile.gifmaker 491 461 -6%
com.baidu.BaiduMap 479 366 -23%
com.taobao.taobao 1341 1198 -11%
com.baidu.searchbox 333 314 -6%
com.tencent.mobileqq 394 384 -3%
com.sina.weibo 907 906 0%
com.youku.phone 816 731 -11%
com.happyelements.AndroidAnimal.qq 763 717 -6%
com.UCMobile 415 411 -1%
com.tencent.tmgp.ak 1464 1431 -2%
com.tencent.qqmusic 336 329 -2%
com.sankuai.meituan 1661 1302 -22%
com.netease.cloudmusic 1193 1200 1%
air.tv.douyu.android 4257 4152 -2%
------------------
Benchmarks results
Base kernel is v4.17.0-rc4-mm1
SPF is BASE + this series
Kernbench:
----------
Here are the results on a 16 CPUs X86 guest using kernbench on a 4.15
kernel (kernel is build 5 times):
Average Half load -j 8
Run (std deviation)
BASE SPF
Elapsed Time 1448.65 (5.72312) 1455.84 (4.84951) 0.50%
User Time 10135.4 (30.3699) 10148.8 (31.1252) 0.13%
System Time 900.47 (2.81131) 923.28 (7.52779) 2.53%
Percent CPU 761.4 (1.14018) 760.2 (0.447214) -0.16%
Context Switches 85380 (3419.52) 84748 (1904.44) -0.74%
Sleeps 105064 (1240.96) 105074 (337.612) 0.01%
Average Optimal load -j 16
Run (std deviation)
BASE SPF
Elapsed Time 920.528 (10.1212) 927.404 (8.91789) 0.75%
User Time 11064.8 (981.142) 11085 (990.897) 0.18%
System Time 979.904 (84.0615) 1001.14 (82.5523) 2.17%
Percent CPU 1089.5 (345.894) 1086.1 (343.545) -0.31%
Context Switches 159488 (78156.4) 158223 (77472.1) -0.79%
Sleeps 110566 (5877.49) 110388 (5617.75) -0.16%
During a run on the SPF, perf events were captured:
Performance counter stats for '../kernbench -M':
526743764 faults
210 spf
3 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
2278 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
Very few speculative page faults were recorded as most of the processes
involved are monothreaded (sounds that on this architecture some threads
were created during the kernel build processing).
Here are the kerbench results on a 80 CPUs Power8 system:
Average Half load -j 40
Run (std deviation)
BASE SPF
Elapsed Time 117.152 (0.774642) 117.166 (0.476057) 0.01%
User Time 4478.52 (24.7688) 4479.76 (9.08555) 0.03%
System Time 131.104 (0.720056) 134.04 (0.708414) 2.24%
Percent CPU 3934 (19.7104) 3937.2 (19.0184) 0.08%
Context Switches 92125.4 (576.787) 92581.6 (198.622) 0.50%
Sleeps 317923 (652.499) 318469 (1255.59) 0.17%
Average Optimal load -j 80
Run (std deviation)
BASE SPF
Elapsed Time 107.73 (0.632416) 107.31 (0.584936) -0.39%
User Time 5869.86 (1466.72) 5871.71 (1467.27) 0.03%
System Time 153.728 (23.8573) 157.153 (24.3704) 2.23%
Percent CPU 5418.6 (1565.17) 5436.7 (1580.91) 0.33%
Context Switches 223861 (138865) 225032 (139632) 0.52%
Sleeps 330529 (13495.1) 332001 (14746.2) 0.45%
During a run on the SPF, perf events were captured:
Performance counter stats for '../kernbench -M':
116730856 faults
0 spf
3 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
476 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
Most of the processes involved are monothreaded so SPF is not activated but
there is no impact on the performance.
Ebizzy:
-------
The test is counting the number of records per second it can manage, the
higher is the best. I run it like this 'ebizzy -mTt <nrcpus>'. To get
consistent result I repeated the test 100 times and measure the average
result. The number is the record processes per second, the higher is the
best.
BASE SPF delta
16 CPUs x86 VM 742.57 1490.24 100.69%
80 CPUs P8 node 13105.4 24174.23 84.46%
Here are the performance counter read during a run on a 16 CPUs x86 VM:
Performance counter stats for './ebizzy -mTt 16':
1706379 faults
1674599 spf
30588 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
363 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
And the ones captured during a run on a 80 CPUs Power node:
Performance counter stats for './ebizzy -mTt 80':
1874773 faults
1461153 spf
413293 pagefault:spf_vma_changed
0 pagefault:spf_vma_noanon
200 pagefault:spf_vma_notsup
0 pagefault:spf_vma_access
0 pagefault:spf_pmd_changed
In ebizzy's case most of the page fault were handled in a speculative way,
leading the ebizzy performance boost.
------------------
Changes since v10 (https://lkml.org/lkml/2018/4/17/572):
- Accounted for all review feedbacks from Punit Agrawal, Ganesh Mahendran
and Minchan Kim, hopefully.
- Remove unneeded check on CONFIG_SPECULATIVE_PAGE_FAULT in
__do_page_fault().
- Loop in pte_spinlock() and pte_map_lock() when pte try lock fails
instead
of aborting the speculative page fault handling. Dropping the now
useless
trace event pagefault:spf_pte_lock.
- No more try to reuse the fetched VMA during the speculative page fault
handling when retrying is needed. This adds a lot of complexity and
additional tests done didn't show a significant performance improvement.
- Convert IS_ENABLED(CONFIG_NUMA) back to #ifdef due to build error.
[1] http://linux-kernel.2935.n7.nabble.com/RFC-PATCH-0-6-Another-go-at-speculative-page-faults-tt965642.html#none
[2] https://patchwork.kernel.org/patch/9999687/
Laurent Dufour (20):
mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
mm: introduce pte_spinlock for FAULT_FLAG_SPECULATIVE
mm: make pte_unmap_same compatible with SPF
mm: introduce INIT_VMA()
mm: protect VMA modifications using VMA sequence count
mm: protect mremap() against SPF hanlder
mm: protect SPF handler against anon_vma changes
mm: cache some VMA fields in the vm_fault structure
mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()
mm: introduce __lru_cache_add_active_or_unevictable
mm: introduce __vm_normal_page()
mm: introduce __page_add_new_anon_rmap()
mm: protect mm_rb tree with a rwlock
mm: adding speculative page fault failure trace events
perf: add a speculative page fault sw event
perf tools: add support for the SPF perf event
mm: add speculative page fault vmstats
powerpc/mm: add speculative page fault
Mahendran Ganesh (2):
arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
arm64/mm: add speculative page fault
Peter Zijlstra (4):
mm: prepare for FAULT_FLAG_SPECULATIVE
mm: VMA sequence count
mm: provide speculative fault infrastructure
x86/mm: add speculative pagefault handling
arch/arm64/Kconfig | 1 +
arch/arm64/mm/fault.c | 12 +
arch/powerpc/Kconfig | 1 +
arch/powerpc/mm/fault.c | 16 +
arch/x86/Kconfig | 1 +
arch/x86/mm/fault.c | 27 +-
fs/exec.c | 2 +-
fs/proc/task_mmu.c | 5 +-
fs/userfaultfd.c | 17 +-
include/linux/hugetlb_inline.h | 2 +-
include/linux/migrate.h | 4 +-
include/linux/mm.h | 136 +++++++-
include/linux/mm_types.h | 7 +
include/linux/pagemap.h | 4 +-
include/linux/rmap.h | 12 +-
include/linux/swap.h | 10 +-
include/linux/vm_event_item.h | 3 +
include/trace/events/pagefault.h | 80 +++++
include/uapi/linux/perf_event.h | 1 +
kernel/fork.c | 5 +-
mm/Kconfig | 22 ++
mm/huge_memory.c | 6 +-
mm/hugetlb.c | 2 +
mm/init-mm.c | 3 +
mm/internal.h | 20 ++
mm/khugepaged.c | 5 +
mm/madvise.c | 6 +-
mm/memory.c | 612 +++++++++++++++++++++++++++++-----
mm/mempolicy.c | 51 ++-
mm/migrate.c | 6 +-
mm/mlock.c | 13 +-
mm/mmap.c | 229 ++++++++++---
mm/mprotect.c | 4 +-
mm/mremap.c | 13 +
mm/nommu.c | 2 +-
mm/rmap.c | 5 +-
mm/swap.c | 6 +-
mm/swap_state.c | 8 +-
mm/vmstat.c | 5 +-
tools/include/uapi/linux/perf_event.h | 1 +
tools/perf/util/evsel.c | 1 +
tools/perf/util/parse-events.c | 4 +
tools/perf/util/parse-events.l | 1 +
tools/perf/util/python.c | 1 +
44 files changed, 1161 insertions(+), 211 deletions(-)
create mode 100644 include/trace/events/pagefault.h
--
2.7.4
^ permalink raw reply [flat|nested] 46+ messages in thread
end of thread, other threads:[~2019-01-29 15:40 UTC | newest]
Thread overview: 46+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-01-11 15:43 [PATCH v11 00/26] Speculative page faults Vinayak Menon
2019-01-14 13:19 ` Vinayak Menon
2019-01-15 8:24 ` Laurent Dufour
2019-01-16 11:41 ` Vinayak Menon
2019-01-16 13:31 ` Laurent Dufour
2019-01-16 11:41 ` Vinayak Menon
2019-01-17 15:51 ` zhong jiang
2019-01-17 15:51 ` zhong jiang
2019-01-18 9:29 ` Laurent Dufour
2019-01-18 15:41 ` zhong jiang
2019-01-18 15:41 ` zhong jiang
2019-01-18 15:51 ` Laurent Dufour
2019-01-18 16:24 ` Laurent Dufour
2019-01-19 17:05 ` zhong jiang
2019-01-19 17:05 ` zhong jiang
2019-01-22 16:22 ` zhong jiang
2019-01-22 16:22 ` zhong jiang
2019-01-24 8:20 ` Laurent Dufour
2019-01-25 12:32 ` zhong jiang
2019-01-25 12:32 ` zhong jiang
2019-01-28 8:59 ` Laurent Dufour
2019-01-28 14:09 ` zhong jiang
2019-01-28 14:09 ` zhong jiang
2019-01-28 15:45 ` Laurent Dufour
2019-01-29 15:40 ` zhong jiang
-- strict thread matches above, loose matches on Subject: below --
2018-05-17 11:06 Laurent Dufour
2018-05-28 5:23 ` Song, HaiyanX
2018-05-28 7:51 ` Laurent Dufour
2018-05-28 8:22 ` Haiyan Song
2018-05-28 8:54 ` Laurent Dufour
2018-05-28 11:04 ` Wang, Kemi
2018-06-11 7:49 ` Song, HaiyanX
2018-06-11 15:15 ` Laurent Dufour
2018-06-19 9:16 ` Haiyan Song
2018-07-02 8:59 ` Laurent Dufour
2018-07-04 3:23 ` Song, HaiyanX
2018-07-04 7:51 ` Laurent Dufour
2018-07-11 17:05 ` Laurent Dufour
2018-07-13 3:56 ` Song, HaiyanX
2018-07-17 9:36 ` Laurent Dufour
2018-08-03 6:36 ` Song, HaiyanX
2018-08-03 6:45 ` Song, HaiyanX
2018-08-22 14:23 ` Laurent Dufour
2018-09-18 6:42 ` Song, HaiyanX
2018-11-05 10:42 ` Balbir Singh
2018-11-05 16:08 ` Laurent Dufour
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