* [PATCH v2] arch/sparc: support NR_CPUS = 4096
@ 2017-06-05 22:48 ` Jane Chu
0 siblings, 0 replies; 10+ messages in thread
From: Jane Chu @ 2017-06-05 22:48 UTC (permalink / raw)
To: davem, tglx; +Cc: atish.patra, Liam.Howlett, sparclinux, linux-kernel, jane.chu
Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
only allocates a single page for NR_CPUS mondo entries. Thus we cannot
use all 4096 CPUs on some SPARC platforms.
To fix, allocate (2^order) pages where order is set according to the size
of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
are not used in asm code, there are no imm13 offsets from the base PA
that will break because they can only reach one page.
Orabug: 25505750
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Reviewed-by: Atish Patra <atish.patra@oracle.com>
---
arch/sparc/Kconfig | 4 ++--
arch/sparc/kernel/irq_64.c | 16 ++++++++++++----
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 58243b0..4399be7 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -192,9 +192,9 @@ config NR_CPUS
int "Maximum number of CPUs"
depends on SMP
range 2 32 if SPARC32
- range 2 1024 if SPARC64
+ range 2 4096 if SPARC64
default 32 if SPARC32
- default 64 if SPARC64
+ default 4096 if SPARC64
source kernel/Kconfig.hz
diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
index 4d0248a..cc8f6c3 100644
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -1034,17 +1034,25 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
{
#ifdef CONFIG_SMP
unsigned long page;
+ void *mondo;
- BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
+ BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
+
+ /* Make sure mondo block is 64byte aligned */
+ mondo = kzalloc(64, GFP_KERNEL);
+ if (!mondo) {
+ prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
+ prom_halt();
+ }
+ tb->cpu_mondo_block_pa = __pa(mondo);
page = get_zeroed_page(GFP_KERNEL);
if (!page) {
- prom_printf("SUN4V: Error, cannot allocate cpu mondo page.\n");
+ prom_printf("SUN4V: Error, cannot allocate cpu list page.\n");
prom_halt();
}
- tb->cpu_mondo_block_pa = __pa(page);
- tb->cpu_list_pa = __pa(page + 64);
+ tb->cpu_list_pa = __pa(page);
#endif
}
--
1.7.1
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v2] arch/sparc: support NR_CPUS = 4096
@ 2017-06-05 22:48 ` Jane Chu
0 siblings, 0 replies; 10+ messages in thread
From: Jane Chu @ 2017-06-05 22:48 UTC (permalink / raw)
To: davem, tglx; +Cc: atish.patra, Liam.Howlett, sparclinux, linux-kernel, jane.chu
Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
only allocates a single page for NR_CPUS mondo entries. Thus we cannot
use all 4096 CPUs on some SPARC platforms.
To fix, allocate (2^order) pages where order is set according to the size
of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
are not used in asm code, there are no imm13 offsets from the base PA
that will break because they can only reach one page.
Orabug: 25505750
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Reviewed-by: Atish Patra <atish.patra@oracle.com>
---
arch/sparc/Kconfig | 4 ++--
arch/sparc/kernel/irq_64.c | 16 ++++++++++++----
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 58243b0..4399be7 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -192,9 +192,9 @@ config NR_CPUS
int "Maximum number of CPUs"
depends on SMP
range 2 32 if SPARC32
- range 2 1024 if SPARC64
+ range 2 4096 if SPARC64
default 32 if SPARC32
- default 64 if SPARC64
+ default 4096 if SPARC64
source kernel/Kconfig.hz
diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
index 4d0248a..cc8f6c3 100644
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -1034,17 +1034,25 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
{
#ifdef CONFIG_SMP
unsigned long page;
+ void *mondo;
- BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
+ BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
+
+ /* Make sure mondo block is 64byte aligned */
+ mondo = kzalloc(64, GFP_KERNEL);
+ if (!mondo) {
+ prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
+ prom_halt();
+ }
+ tb->cpu_mondo_block_pa = __pa(mondo);
page = get_zeroed_page(GFP_KERNEL);
if (!page) {
- prom_printf("SUN4V: Error, cannot allocate cpu mondo page.\n");
+ prom_printf("SUN4V: Error, cannot allocate cpu list page.\n");
prom_halt();
}
- tb->cpu_mondo_block_pa = __pa(page);
- tb->cpu_list_pa = __pa(page + 64);
+ tb->cpu_list_pa = __pa(page);
#endif
}
--
1.7.1
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
2017-06-05 22:48 ` Jane Chu
@ 2017-06-06 0:57 ` David Miller
-1 siblings, 0 replies; 10+ messages in thread
From: David Miller @ 2017-06-06 0:57 UTC (permalink / raw)
To: jane.chu; +Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel
From: Jane Chu <jane.chu@oracle.com>
Date: Mon, 5 Jun 2017 16:48:31 -0600
> Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
> only allocates a single page for NR_CPUS mondo entries. Thus we cannot
> use all 4096 CPUs on some SPARC platforms.
>
> To fix, allocate (2^order) pages where order is set according to the size
> of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
> are not used in asm code, there are no imm13 offsets from the base PA
> that will break because they can only reach one page.
>
> Orabug: 25505750
>
> Signed-off-by: Jane Chu <jane.chu@oracle.com>
>
> Reviewed-by: Bob Picco <bob.picco@oracle.com>
> Reviewed-by: Atish Patra <atish.patra@oracle.com>
> ---
> arch/sparc/Kconfig | 4 ++--
> arch/sparc/kernel/irq_64.c | 16 ++++++++++++----
> 2 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 58243b0..4399be7 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -192,9 +192,9 @@ config NR_CPUS
> int "Maximum number of CPUs"
> depends on SMP
> range 2 32 if SPARC32
> - range 2 1024 if SPARC64
> + range 2 4096 if SPARC64
> default 32 if SPARC32
> - default 64 if SPARC64
> + default 4096 if SPARC64
>
> source kernel/Kconfig.hz
>
> diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
> index 4d0248a..cc8f6c3 100644
> --- a/arch/sparc/kernel/irq_64.c
> +++ b/arch/sparc/kernel/irq_64.c
> @@ -1034,17 +1034,25 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
> {
> #ifdef CONFIG_SMP
> unsigned long page;
> + void *mondo;
>
> - BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
> + BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
> +
> + /* Make sure mondo block is 64byte aligned */
> + mondo = kzalloc(64, GFP_KERNEL);
> + if (!mondo) {
> + prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
> + prom_halt();
> + }
> + tb->cpu_mondo_block_pa = __pa(mondo);
Hmmm, you said that this has to be 64 byte aligned right? We might have
to do something in order to insure that, as kmalloc() only guarantees
ARCH_KMALLOC_MINALIGN which I think is 8 on sparc.
I suppose this would work:
mondo = kzalloc(64 + 63, GFP_KERNEL);
and then 64-byte align that pointer.
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
@ 2017-06-06 0:57 ` David Miller
0 siblings, 0 replies; 10+ messages in thread
From: David Miller @ 2017-06-06 0:57 UTC (permalink / raw)
To: jane.chu; +Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel
From: Jane Chu <jane.chu@oracle.com>
Date: Mon, 5 Jun 2017 16:48:31 -0600
> Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
> only allocates a single page for NR_CPUS mondo entries. Thus we cannot
> use all 4096 CPUs on some SPARC platforms.
>
> To fix, allocate (2^order) pages where order is set according to the size
> of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
> are not used in asm code, there are no imm13 offsets from the base PA
> that will break because they can only reach one page.
>
> Orabug: 25505750
>
> Signed-off-by: Jane Chu <jane.chu@oracle.com>
>
> Reviewed-by: Bob Picco <bob.picco@oracle.com>
> Reviewed-by: Atish Patra <atish.patra@oracle.com>
> ---
> arch/sparc/Kconfig | 4 ++--
> arch/sparc/kernel/irq_64.c | 16 ++++++++++++----
> 2 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 58243b0..4399be7 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -192,9 +192,9 @@ config NR_CPUS
> int "Maximum number of CPUs"
> depends on SMP
> range 2 32 if SPARC32
> - range 2 1024 if SPARC64
> + range 2 4096 if SPARC64
> default 32 if SPARC32
> - default 64 if SPARC64
> + default 4096 if SPARC64
>
> source kernel/Kconfig.hz
>
> diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
> index 4d0248a..cc8f6c3 100644
> --- a/arch/sparc/kernel/irq_64.c
> +++ b/arch/sparc/kernel/irq_64.c
> @@ -1034,17 +1034,25 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
> {
> #ifdef CONFIG_SMP
> unsigned long page;
> + void *mondo;
>
> - BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
> + BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
> +
> + /* Make sure mondo block is 64byte aligned */
> + mondo = kzalloc(64, GFP_KERNEL);
> + if (!mondo) {
> + prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
> + prom_halt();
> + }
> + tb->cpu_mondo_block_pa = __pa(mondo);
Hmmm, you said that this has to be 64 byte aligned right? We might have
to do something in order to insure that, as kmalloc() only guarantees
ARCH_KMALLOC_MINALIGN which I think is 8 on sparc.
I suppose this would work:
mondo = kzalloc(64 + 63, GFP_KERNEL);
and then 64-byte align that pointer.
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
2017-06-06 0:57 ` David Miller
@ 2017-06-06 3:03 ` jane.chu
-1 siblings, 0 replies; 10+ messages in thread
From: jane.chu @ 2017-06-06 3:03 UTC (permalink / raw)
To: David Miller
Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel, JANE.CHU
On 06/05/2017 05:57 PM, David Miller wrote:
> From: Jane Chu <jane.chu@oracle.com>
> Date: Mon, 5 Jun 2017 16:48:31 -0600
>
>> Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
>> only allocates a single page for NR_CPUS mondo entries. Thus we cannot
>> use all 4096 CPUs on some SPARC platforms.
>>
>> To fix, allocate (2^order) pages where order is set according to the size
>> of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
>> are not used in asm code, there are no imm13 offsets from the base PA
>> that will break because they can only reach one page.
>>
>> Orabug: 25505750
>>
>> Signed-off-by: Jane Chu <jane.chu@oracle.com>
>>
>> Reviewed-by: Bob Picco <bob.picco@oracle.com>
>> Reviewed-by: Atish Patra <atish.patra@oracle.com>
>> ---
>> arch/sparc/Kconfig | 4 ++--
>> arch/sparc/kernel/irq_64.c | 16 ++++++++++++----
>> 2 files changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
>> index 58243b0..4399be7 100644
>> --- a/arch/sparc/Kconfig
>> +++ b/arch/sparc/Kconfig
>> @@ -192,9 +192,9 @@ config NR_CPUS
>> int "Maximum number of CPUs"
>> depends on SMP
>> range 2 32 if SPARC32
>> - range 2 1024 if SPARC64
>> + range 2 4096 if SPARC64
>> default 32 if SPARC32
>> - default 64 if SPARC64
>> + default 4096 if SPARC64
>>
>> source kernel/Kconfig.hz
>>
>> diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
>> index 4d0248a..cc8f6c3 100644
>> --- a/arch/sparc/kernel/irq_64.c
>> +++ b/arch/sparc/kernel/irq_64.c
>> @@ -1034,17 +1034,25 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
>> {
>> #ifdef CONFIG_SMP
>> unsigned long page;
>> + void *mondo;
>>
>> - BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
>> + BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
>> +
>> + /* Make sure mondo block is 64byte aligned */
>> + mondo = kzalloc(64, GFP_KERNEL);
>> + if (!mondo) {
>> + prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
>> + prom_halt();
>> + }
>> + tb->cpu_mondo_block_pa = __pa(mondo);
> Hmmm, you said that this has to be 64 byte aligned right? We might have
> to do something in order to insure that, as kmalloc() only guarantees
> ARCH_KMALLOC_MINALIGN which I think is 8 on sparc.
Yes.
>
> I suppose this would work:
>
> mondo = kzalloc(64 + 63, GFP_KERNEL);
>
> and then 64-byte align that pointer.
On sun4v sparc, it looks like kzalloc(64, GFP_KERNEL) ends up allocating
from kmalloc_caches[6] - a 64-byte kmem-cache allocated by
kmem_cache_init() with SLAB_HWCACHE_ALIGN flag set, so it's in
l3-cache-line-size
alignment, i.e. 64byte. I printed out the 'mondo' pa and verified that.
thanks!
-jane
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
@ 2017-06-06 3:03 ` jane.chu
0 siblings, 0 replies; 10+ messages in thread
From: jane.chu @ 2017-06-06 3:03 UTC (permalink / raw)
To: David Miller
Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel, JANE.CHU
On 06/05/2017 05:57 PM, David Miller wrote:
> From: Jane Chu <jane.chu@oracle.com>
> Date: Mon, 5 Jun 2017 16:48:31 -0600
>
>> Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
>> only allocates a single page for NR_CPUS mondo entries. Thus we cannot
>> use all 4096 CPUs on some SPARC platforms.
>>
>> To fix, allocate (2^order) pages where order is set according to the size
>> of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
>> are not used in asm code, there are no imm13 offsets from the base PA
>> that will break because they can only reach one page.
>>
>> Orabug: 25505750
>>
>> Signed-off-by: Jane Chu <jane.chu@oracle.com>
>>
>> Reviewed-by: Bob Picco <bob.picco@oracle.com>
>> Reviewed-by: Atish Patra <atish.patra@oracle.com>
>> ---
>> arch/sparc/Kconfig | 4 ++--
>> arch/sparc/kernel/irq_64.c | 16 ++++++++++++----
>> 2 files changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
>> index 58243b0..4399be7 100644
>> --- a/arch/sparc/Kconfig
>> +++ b/arch/sparc/Kconfig
>> @@ -192,9 +192,9 @@ config NR_CPUS
>> int "Maximum number of CPUs"
>> depends on SMP
>> range 2 32 if SPARC32
>> - range 2 1024 if SPARC64
>> + range 2 4096 if SPARC64
>> default 32 if SPARC32
>> - default 64 if SPARC64
>> + default 4096 if SPARC64
>>
>> source kernel/Kconfig.hz
>>
>> diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
>> index 4d0248a..cc8f6c3 100644
>> --- a/arch/sparc/kernel/irq_64.c
>> +++ b/arch/sparc/kernel/irq_64.c
>> @@ -1034,17 +1034,25 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
>> {
>> #ifdef CONFIG_SMP
>> unsigned long page;
>> + void *mondo;
>>
>> - BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
>> + BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
>> +
>> + /* Make sure mondo block is 64byte aligned */
>> + mondo = kzalloc(64, GFP_KERNEL);
>> + if (!mondo) {
>> + prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
>> + prom_halt();
>> + }
>> + tb->cpu_mondo_block_pa = __pa(mondo);
> Hmmm, you said that this has to be 64 byte aligned right? We might have
> to do something in order to insure that, as kmalloc() only guarantees
> ARCH_KMALLOC_MINALIGN which I think is 8 on sparc.
Yes.
>
> I suppose this would work:
>
> mondo = kzalloc(64 + 63, GFP_KERNEL);
>
> and then 64-byte align that pointer.
On sun4v sparc, it looks like kzalloc(64, GFP_KERNEL) ends up allocating
from kmalloc_caches[6] - a 64-byte kmem-cache allocated by
kmem_cache_init() with SLAB_HWCACHE_ALIGN flag set, so it's in
l3-cache-line-size
alignment, i.e. 64byte. I printed out the 'mondo' pa and verified that.
thanks!
-jane
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
2017-06-06 3:03 ` jane.chu
@ 2017-06-06 3:27 ` David Miller
-1 siblings, 0 replies; 10+ messages in thread
From: David Miller @ 2017-06-06 3:27 UTC (permalink / raw)
To: jane.chu; +Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel
From: jane.chu@oracle.com
Date: Mon, 5 Jun 2017 20:03:28 -0700
> On sun4v sparc, it looks like kzalloc(64, GFP_KERNEL) ends up
> allocating from kmalloc_caches[6] - a 64-byte kmem-cache allocated
> by kmem_cache_init() with SLAB_HWCACHE_ALIGN flag set, so it's in
> l3-cache-line-size alignment, i.e. 64byte. I printed out the
> 'mondo' pa and verified that.
Please check this, because that is an implementation detail. We have
three SLAB allocators.
For example, if the user enables SLOB, I bet you don't get that
alignment.
The only thing we are universally guaranteed is ARCH_KMALLOC_MINALIGN.
Please implement this properly, rather than relying upon things like
the above.
Thank you.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
@ 2017-06-06 3:27 ` David Miller
0 siblings, 0 replies; 10+ messages in thread
From: David Miller @ 2017-06-06 3:27 UTC (permalink / raw)
To: jane.chu; +Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel
From: jane.chu@oracle.com
Date: Mon, 5 Jun 2017 20:03:28 -0700
> On sun4v sparc, it looks like kzalloc(64, GFP_KERNEL) ends up
> allocating from kmalloc_caches[6] - a 64-byte kmem-cache allocated
> by kmem_cache_init() with SLAB_HWCACHE_ALIGN flag set, so it's in
> l3-cache-line-size alignment, i.e. 64byte. I printed out the
> 'mondo' pa and verified that.
Please check this, because that is an implementation detail. We have
three SLAB allocators.
For example, if the user enables SLOB, I bet you don't get that
alignment.
The only thing we are universally guaranteed is ARCH_KMALLOC_MINALIGN.
Please implement this properly, rather than relying upon things like
the above.
Thank you.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
2017-06-06 3:27 ` David Miller
@ 2017-06-06 17:04 ` jane.chu
-1 siblings, 0 replies; 10+ messages in thread
From: jane.chu @ 2017-06-06 17:04 UTC (permalink / raw)
To: David Miller; +Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel
On 06/05/2017 08:27 PM, David Miller wrote:
> From: jane.chu@oracle.com
> Date: Mon, 5 Jun 2017 20:03:28 -0700
>
>> On sun4v sparc, it looks like kzalloc(64, GFP_KERNEL) ends up
>> allocating from kmalloc_caches[6] - a 64-byte kmem-cache allocated
>> by kmem_cache_init() with SLAB_HWCACHE_ALIGN flag set, so it's in
>> l3-cache-line-size alignment, i.e. 64byte. I printed out the
>> 'mondo' pa and verified that.
> Please check this, because that is an implementation detail. We have
> three SLAB allocators.
>
> For example, if the user enables SLOB, I bet you don't get that
> alignment.
>
> The only thing we are universally guaranteed is ARCH_KMALLOC_MINALIGN.
>
> Please implement this properly, rather than relying upon things like
> the above.
Good point, agreed. I will update the patch.
thanks!
-jane
>
> Thank you.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2] arch/sparc: support NR_CPUS = 4096
@ 2017-06-06 17:04 ` jane.chu
0 siblings, 0 replies; 10+ messages in thread
From: jane.chu @ 2017-06-06 17:04 UTC (permalink / raw)
To: David Miller; +Cc: tglx, atish.patra, Liam.Howlett, sparclinux, linux-kernel
On 06/05/2017 08:27 PM, David Miller wrote:
> From: jane.chu@oracle.com
> Date: Mon, 5 Jun 2017 20:03:28 -0700
>
>> On sun4v sparc, it looks like kzalloc(64, GFP_KERNEL) ends up
>> allocating from kmalloc_caches[6] - a 64-byte kmem-cache allocated
>> by kmem_cache_init() with SLAB_HWCACHE_ALIGN flag set, so it's in
>> l3-cache-line-size alignment, i.e. 64byte. I printed out the
>> 'mondo' pa and verified that.
> Please check this, because that is an implementation detail. We have
> three SLAB allocators.
>
> For example, if the user enables SLOB, I bet you don't get that
> alignment.
>
> The only thing we are universally guaranteed is ARCH_KMALLOC_MINALIGN.
>
> Please implement this properly, rather than relying upon things like
> the above.
Good point, agreed. I will update the patch.
thanks!
-jane
>
> Thank you.
^ permalink raw reply [flat|nested] 10+ messages in thread
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2017-06-05 22:48 [PATCH v2] arch/sparc: support NR_CPUS = 4096 Jane Chu
2017-06-05 22:48 ` Jane Chu
2017-06-06 0:57 ` David Miller
2017-06-06 0:57 ` David Miller
2017-06-06 3:03 ` jane.chu
2017-06-06 3:03 ` jane.chu
2017-06-06 3:27 ` David Miller
2017-06-06 3:27 ` David Miller
2017-06-06 17:04 ` jane.chu
2017-06-06 17:04 ` jane.chu
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