* [stable-4.14 01/11] mm: workingset: don't drop refault information prematurely
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 16:37 ` Linus Torvalds
2019-03-12 10:19 ` [stable-4.14 02/11] mm: workingset: tell cache transitions from workingset thrashing Jack Wang
` (10 subsequent siblings)
11 siblings, 1 reply; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Ingo Molnar, Tejun Heo, Vinayak Menon,
Christopher Lameter, Peter Enderborg, Shakeel Butt,
Mike Galbraith, Randy Dunlap, Andrew Morton, Linus Torvalds,
Jack Wang
From: Johannes Weiner <jweiner@fb.com>
Patch series "psi: pressure stall information for CPU, memory, and IO", v4.
Overview
PSI reports the overall wallclock time in which the tasks in a system (or
cgroup) wait for (contended) hardware resources.
This helps users understand the resource pressure their workloads are
under, which allows them to rootcause and fix throughput and latency
problems caused by overcommitting, underprovisioning, suboptimal job
placement in a grid; as well as anticipate major disruptions like OOM.
Real-world applications
We're using the data collected by PSI (and its previous incarnation,
memdelay) quite extensively at Facebook, and with several success stories.
One usecase is avoiding OOM hangs/livelocks. The reason these happen is
because the OOM killer is triggered by reclaim not being able to free
pages, but with fast flash devices there is *always* some clean and
uptodate cache to reclaim; the OOM killer never kicks in, even as tasks
spend 90% of the time thrashing the cache pages of their own executables.
There is no situation where this ever makes sense in practice. We wrote a
<100 line POC python script to monitor memory pressure and kill stuff way
before such pathological thrashing leads to full system losses that would
require forcible hard resets.
We've since extended and deployed this code into other places to guarantee
latency and throughput SLAs, since they're usually violated way before the
kernel OOM killer would ever kick in.
It is available here: https://github.com/facebookincubator/oomd
Eventually we probably want to trigger the in-kernel OOM killer based on
extreme sustained pressure as well, so that Linux can avoid memory
livelocks - which technically aren't deadlocks, but to the user
indistinguishable from them - out of the box. We'd continue using OOMD as
the first line of defense to ensure workload health and implement complex
kill policies that are beyond the scope of the kernel.
We also use PSI memory pressure for loadshedding. Our batch job
infrastructure used to use heuristics based on various VM stats to
anticipate OOM situations, with lackluster success. We switched it to PSI
and managed to anticipate and avoid OOM kills and lockups fairly reliably.
The reduction of OOM outages in the worker pool raised the pool's
aggregate productivity, and we were able to switch that service to smaller
machines.
Lastly, we use cgroups to isolate a machine's main workload from
maintenance crap like package upgrades, logging, configuration, as well as
to prevent multiple workloads on a machine from stepping on each others'
toes. We were not able to configure this properly without the pressure
metrics; we would see latency or bandwidth drops, but it would often be
hard to impossible to rootcause it post-mortem.
We now log and graph pressure for the containers in our fleet and can
trivially link latency spikes and throughput drops to shortages of
specific resources after the fact, and fix the job config/scheduling.
PSI has also received testing, feedback, and feature requests from Android
and EndlessOS for the purpose of low-latency OOM killing, to intervene in
pressure situations before the UI starts hanging.
How do you use this feature?
A kernel with CONFIG_PSI=y will create a /proc/pressure directory with 3
files: cpu, memory, and io. If using cgroup2, cgroups will also have
cpu.pressure, memory.pressure and io.pressure files, which simply
aggregate task stalls at the cgroup level instead of system-wide.
The cpu file contains one line:
some avg10=2.04 avg60=0.75 avg300=0.40 total=157656722
The averages give the percentage of walltime in which one or more tasks
are delayed on the runqueue while another task has the CPU. They're
recent averages over 10s, 1m, 5m windows, so you can tell short term
trends from long term ones, similarly to the load average.
The total= value gives the absolute stall time in microseconds. This
allows detecting latency spikes that might be too short to sway the
running averages. It also allows custom time averaging in case the
10s/1m/5m windows aren't adequate for the usecase (or are too coarse with
future hardware).
What to make of this "some" metric? If CPU utilization is at 100% and CPU
pressure is 0, it means the system is perfectly utilized, with one
runnable thread per CPU and nobody waiting. At two or more runnable tasks
per CPU, the system is 100% overcommitted and the pressure average will
indicate as much. From a utilization perspective this is a great state of
course: no CPU cycles are being wasted, even when 50% of the threads were
to go idle (as most workloads do vary). From the perspective of the
individual job it's not great, however, and they would do better with more
resources. Depending on what your priority and options are, raised "some"
numbers may or may not require action.
The memory file contains two lines:
some avg10=70.24 avg60=68.52 avg300=69.91 total=3559632828
full avg10=57.59 avg60=58.06 avg300=60.38 total=3300487258
The some line is the same as for cpu, the time in which at least one task
is stalled on the resource. In the case of memory, this includes waiting
on swap-in, page cache refaults and page reclaim.
The full line, however, indicates time in which *nobody* is using the CPU
productively due to pressure: all non-idle tasks are waiting for memory in
one form or another. Significant time spent in there is a good trigger
for killing things, moving jobs to other machines, or dropping incoming
requests, since neither the jobs nor the machine overall are making too
much headway.
The io file is similar to memory. Because the block layer doesn't have a
concept of hardware contention right now (how much longer is my IO request
taking due to other tasks?), it reports CPU potential lost on all IO
delays, not just the potential lost due to competition.
FAQ
Q: How is PSI's CPU component different from the load average?
A: There are several quirks in the load average that make it hard to
impossible to tell how overcommitted the CPU really is.
1. The load average is reported as a raw number of active tasks.
You need to know how many CPUs there are in the system, how many
CPUs the workload is allowed to use, then think about what the
proportion between load and the number of CPUs mean for the
tasks trying to run.
PSI reports the percentage of wallclock time in which tasks are
waiting for a CPU to run on. It doesn't matter how many CPUs are
present or usable. The number always tells the quality of life
of tasks in the system or in a particular cgroup.
2. The shortest averaging window is 1m, which is extremely coarse,
and it's sampled in 5s intervals. A *lot* can happen on a CPU in
5 seconds. This *may* be able to identify persistent long-term
trends and very clear and obvious overloads, but it's unusable
for latency spikes and more subtle overutilization.
PSI's shortest window is 10s. It also exports the cumulative
stall times (in microseconds) of synchronously recorded events.
3. On Linux, the load average for historical reasons includes all
TASK_UNINTERRUPTIBLE tasks. This gives a broader sense of how
busy the system is, but on the flipside it doesn't distinguish
whether tasks are likely to contend over the CPU or IO - which
obviously requires very different interventions from a sys admin
or a job scheduler.
PSI reports independent metrics for CPU and IO. You can tell
which resource is making the tasks wait, but in conjunction
still see how overloaded the system is overall.
Q: What's the cost / performance impact of this feature?
A: PSI's primary cost is in the scheduler, in particular task wakeups
and sleeps.
I benchmarked this code using Facebook's two most scheduling
sensitive workloads: memcache and webserver. They handle a ton of
small requests - lots of wakeups and sleeps with little actual work
in between - so they tend to be canaries for scheduler regressions.
In the tests, the boxes were handling live traffic over the course
of several hours. Half the machines, the control, ran with
CONFIG_PSI=n.
For memcache I used eight machines total. They're 2-socket, 14
core, 56 thread boxes. The test runs for half the test period,
flips the test and control kernels on the hardware to rule out HW
factors, DC location etc., then runs the other half of the test.
For the webservers, I used 32 machines total. They're single
socket, 16 core, 32 thread machines.
During the memcache test, CPU load was nopsi=78.05% psi=78.98% in
the first half and nopsi=77.52% psi=78.25%, so PSI added between
0.7 and 0.9 percentage points to the CPU load, a difference of
about 1%.
UPDATE: I re-ran this test with the v3 version of this patch set
and the CPU utilization was equivalent between test and control.
UPDATE: v4 is on par with v3.
As far as end-to-end request latency from the client perspective
goes, we don't sample those finely enough to capture the requests
going to those particular machines during the test, but we know the
p50 turnaround time in this workload is 54us, and perf bench sched
pipe on those machines show nopsi=5.232666 us/op and psi=5.587347
us/op, so this doesn't add much here either.
The profile for the pipe benchmark shows:
0.87% sched-pipe [kernel.vmlinux] [k] psi_group_change
0.83% perf.real [kernel.vmlinux] [k] psi_group_change
0.82% perf.real [kernel.vmlinux] [k] psi_task_change
0.58% sched-pipe [kernel.vmlinux] [k] psi_task_change
The webserver load is running inside 4 nested cgroup levels. The
CPU load with both nopsi and psi kernels was indistinguishable at
81%.
For comparison, we had to disable the cgroup cpu controller on the
webservers because it added 4 percentage points to the CPU% during
this same exact test.
Versions of this accounting code now run on 80% of our fleet. None
of our workloads have reported regressions during the rollout.
Daniel Drake said:
: I just retested the latest version at
: http://git.cmpxchg.org/cgit.cgi/linux-psi.git (Linux 4.18) and the results
: are great.
:
: Test setup:
: Endless OS
: GeminiLake N4200 low end laptop
: 2GB RAM
: swap (and zram swap) disabled
:
: Baseline test: open a handful of large-ish apps and several website
: tabs in Google Chrome.
:
: Results: after a couple of minutes, system is excessively thrashing, mouse
: cursor can barely be moved, UI is not responding to mouse clicks, so it's
: impractical to recover from this situation as an ordinary user
:
: Add my simple killer:
: https://gist.github.com/dsd/a8988bf0b81a6163475988120fe8d9cd
:
: Results: when the thrashing causes the UI to become sluggish, the killer
: steps in and kills something (usually a chrome tab), and the system
: remains usable. I repeatedly opened more apps and more websites over a 15
: minute period but I wasn't able to get the system to a point of UI
: unresponsiveness.
Suren said:
: Backported to 4.9 and retested on ARMv8 8 code system running Android.
: Signals behave as expected reacting to memory pressure, no jumps in
: "total" counters that would indicate an overflow/underflow issues. Nicely
: done!
This patch (of 9):
If we keep just enough refault information to match the *current* page
cache during reclaim time, we could lose a lot of events when there is
only a temporary spike in non-cache memory consumption that pushes out all
the cache. Once cache comes back, we won't see those refaults. They
might not be actionable for LRU aging, but we want to know about them for
measuring memory pressure.
[hannes@cmpxchg.org: switch to NUMA-aware lru and slab counters]
Link: http://lkml.kernel.org/r/20181009184732.762-2-hannes@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <jweiner@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit cc75eb49e70d6e084f9327c03e076bc04a351b6b)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
mm/workingset.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/mm/workingset.c b/mm/workingset.c
index b997c9de28f6..a1d3ccf1cd24 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -370,7 +370,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
{
unsigned long max_nodes;
unsigned long nodes;
- unsigned long cache;
+ unsigned long pages;
/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
local_irq_disable();
@@ -399,14 +399,20 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
*
* PAGE_SIZE / radix_tree_nodes / node_entries * 8 / PAGE_SIZE
*/
+#ifdef CONFIG_MEMCG
if (sc->memcg) {
- cache = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
- LRU_ALL_FILE);
- } else {
- cache = node_page_state(NODE_DATA(sc->nid), NR_ACTIVE_FILE) +
- node_page_state(NODE_DATA(sc->nid), NR_INACTIVE_FILE);
- }
- max_nodes = cache >> (RADIX_TREE_MAP_SHIFT - 3);
+ struct lruvec *lruvec;
+
+ pages = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
+ LRU_ALL);
+ lruvec = mem_cgroup_lruvec(NODE_DATA(sc->nid), sc->memcg);
+ pages += lruvec_page_state(lruvec, NR_SLAB_RECLAIMABLE);
+ pages += lruvec_page_state(lruvec, NR_SLAB_UNRECLAIMABLE);
+ } else
+#endif
+ pages = node_present_pages(sc->nid);
+
+ max_nodes = pages >> (RADIX_TREE_MAP_SHIFT - 3);
if (nodes <= max_nodes)
return 0;
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* Re: [stable-4.14 01/11] mm: workingset: don't drop refault information prematurely
2019-03-12 10:19 ` [stable-4.14 01/11] mm: workingset: don't drop refault information prematurely Jack Wang
@ 2019-03-12 16:37 ` Linus Torvalds
2019-03-13 10:05 ` Jinpu Wang
0 siblings, 1 reply; 18+ messages in thread
From: Linus Torvalds @ 2019-03-12 16:37 UTC (permalink / raw)
To: Jack Wang
Cc: Greg Kroah-Hartman, stable, Johannes Weiner, Ingo Molnar,
Tejun Heo, Vinayak Menon, Christopher Lameter, Peter Enderborg,
Shakeel Butt, Mike Galbraith, Randy Dunlap, Andrew Morton,
Jack Wang
On Tue, Mar 12, 2019 at 3:20 AM Jack Wang <jinpuwang@gmail.com> wrote:
>
> Patch series "psi: pressure stall information for CPU, memory, and IO", v4.
This really doesn't look like stable material, it's a fundamental new
feature rather than a "fix".
Linus
^ permalink raw reply [flat|nested] 18+ messages in thread* Re: [stable-4.14 01/11] mm: workingset: don't drop refault information prematurely
2019-03-12 16:37 ` Linus Torvalds
@ 2019-03-13 10:05 ` Jinpu Wang
0 siblings, 0 replies; 18+ messages in thread
From: Jinpu Wang @ 2019-03-13 10:05 UTC (permalink / raw)
To: Linus Torvalds
Cc: Jack Wang, Greg Kroah-Hartman, stable, Johannes Weiner,
Ingo Molnar, Tejun Heo, Vinayak Menon, Christopher Lameter,
Peter Enderborg, Shakeel Butt, Mike Galbraith, Randy Dunlap,
Andrew Morton
On Tue, Mar 12, 2019 at 5:44 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Tue, Mar 12, 2019 at 3:20 AM Jack Wang <jinpuwang@gmail.com> wrote:
> >
> > Patch series "psi: pressure stall information for CPU, memory, and IO", v4.
>
> This really doesn't look like stable material, it's a fundamental new
> feature rather than a "fix".
>
> Linus
Thanks for reply, Linus.
The intention was to get a review and to see if any others can be beneficial.
Wasn't expecting to be merge by 4.14 upstream.
I mentioned in the cover letter.
https://www.spinics.net/lists/stable/msg289978.html
Regards,
--
Jack Wang
Linux Kernel Developer
1&1 IONOS Cloud GmbH | Greifswalder Str. 207 | 10405 Berlin | Germany
Phone: +49 30 57700-8042 | Fax: +49 30 57700-8598
E-mail: jinpu.wang@cloud.ionos.com | Web: www.ionos.de
Head Office: Berlin, Germany
District Court Berlin Charlottenburg, Registration number: HRB 125506 B
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Member of United Internet
This e-mail may contain confidential and/or privileged information. If
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^ permalink raw reply [flat|nested] 18+ messages in thread
* [stable-4.14 02/11] mm: workingset: tell cache transitions from workingset thrashing
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
2019-03-12 10:19 ` [stable-4.14 01/11] mm: workingset: don't drop refault information prematurely Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 10:19 ` [stable-4.14 03/11] delayacct: track delays from thrashing cache pages Jack Wang
` (9 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Tejun Heo, Vinayak Menon, Andrew Morton,
Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
Refaults happen during transitions between workingsets as well as in-place
thrashing. Knowing the difference between the two has a range of
applications, including measuring the impact of memory shortage on the
system performance, as well as the ability to smarter balance pressure
between the filesystem cache and the swap-backed workingset.
During workingset transitions, inactive cache refaults and pushes out
established active cache. When that active cache isn't stale, however,
and also ends up refaulting, that's bonafide thrashing.
Introduce a new page flag that tells on eviction whether the page has been
active or not in its lifetime. This bit is then stored in the shadow
entry, to classify refaults as transitioning or thrashing.
How many page->flags does this leave us with on 32-bit?
20 bits are always page flags
21 if you have an MMU
23 with the zone bits for DMA, Normal, HighMem, Movable
29 with the sparsemem section bits
30 if PAE is enabled
31 with this patch.
So on 32-bit PAE, that leaves 1 bit for distinguishing two NUMA nodes. If
that's not enough, the system can switch to discontigmem and re-gain the 6
or 7 sparsemem section bits.
Link: http://lkml.kernel.org/r/20180828172258.3185-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 2cbfbc7903756e79b10ac97e44be2e80d1b091c6)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
include/linux/mmzone.h | 1 +
include/linux/page-flags.h | 5 +-
include/linux/swap.h | 2 +-
include/trace/events/mmflags.h | 1 +
mm/filemap.c | 9 ++--
mm/huge_memory.c | 1 +
mm/migrate.c | 2 +
mm/swap_state.c | 1 +
mm/vmscan.c | 1 +
mm/vmstat.c | 1 +
mm/workingset.c | 95 ++++++++++++++++++++++------------
11 files changed, 77 insertions(+), 42 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f679f5268467..71b7a8bc82ea 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -163,6 +163,7 @@ enum node_stat_item {
NR_ISOLATED_FILE, /* Temporary isolated pages from file lru */
WORKINGSET_REFAULT,
WORKINGSET_ACTIVATE,
+ WORKINGSET_RESTORE,
WORKINGSET_NODERECLAIM,
NR_ANON_MAPPED, /* Mapped anonymous pages */
NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 584b14c774c1..6900ad07554b 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -74,13 +74,14 @@
*/
enum pageflags {
PG_locked, /* Page is locked. Don't touch. */
- PG_error,
PG_referenced,
PG_uptodate,
PG_dirty,
PG_lru,
PG_active,
+ PG_workingset,
PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
+ PG_error,
PG_slab,
PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
PG_arch_1,
@@ -273,6 +274,8 @@ PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
TESTCLEARFLAG(Active, active, PF_HEAD)
+PAGEFLAG(Workingset, workingset, PF_HEAD)
+ TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
__PAGEFLAG(Slab, slab, PF_NO_TAIL)
__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4fd1ab9565ba..1db5eca571d3 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -304,7 +304,7 @@ struct vma_swap_readahead {
/* linux/mm/workingset.c */
void *workingset_eviction(struct address_space *mapping, struct page *page);
-bool workingset_refault(void *shadow);
+void workingset_refault(struct page *page, void *shadow);
void workingset_activation(struct page *page);
void workingset_update_node(struct radix_tree_node *node, void *private);
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 72162f3a03fa..40b9cc3bfaf9 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -89,6 +89,7 @@
{1UL << PG_dirty, "dirty" }, \
{1UL << PG_lru, "lru" }, \
{1UL << PG_active, "active" }, \
+ {1UL << PG_workingset, "workingset" }, \
{1UL << PG_slab, "slab" }, \
{1UL << PG_owner_priv_1, "owner_priv_1" }, \
{1UL << PG_arch_1, "arch_1" }, \
diff --git a/mm/filemap.c b/mm/filemap.c
index e2e738cc08b1..9f995985e12f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -817,12 +817,9 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
* data from the working set, only to cache data that will
* get overwritten with something else, is a waste of memory.
*/
- if (!(gfp_mask & __GFP_WRITE) &&
- shadow && workingset_refault(shadow)) {
- SetPageActive(page);
- workingset_activation(page);
- } else
- ClearPageActive(page);
+ WARN_ON_ONCE(PageActive(page));
+ if (!(gfp_mask & __GFP_WRITE) && shadow)
+ workingset_refault(page, shadow);
lru_cache_add(page);
}
return ret;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 930f2aa3bb4d..4ef967ad24ec 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2327,6 +2327,7 @@ static void __split_huge_page_tail(struct page *head, int tail,
(1L << PG_mlocked) |
(1L << PG_uptodate) |
(1L << PG_active) |
+ (1L << PG_workingset) |
(1L << PG_locked) |
(1L << PG_unevictable) |
(1L << PG_dirty)));
diff --git a/mm/migrate.c b/mm/migrate.c
index 8c57cdd77ba5..4e018550f8e7 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -673,6 +673,8 @@ void migrate_page_states(struct page *newpage, struct page *page)
SetPageActive(newpage);
} else if (TestClearPageUnevictable(page))
SetPageUnevictable(newpage);
+ if (PageWorkingset(page))
+ SetPageWorkingset(newpage);
if (PageChecked(page))
SetPageChecked(newpage);
if (PageMappedToDisk(page))
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 326439428daf..3931379fac4d 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -435,6 +435,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
/*
* Initiate read into locked page and return.
*/
+ SetPageWorkingset(new_page);
lru_cache_add_anon(new_page);
*new_page_allocated = true;
return new_page;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9734e62654fa..06a7d1605a5d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2056,6 +2056,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
}
ClearPageActive(page); /* we are de-activating */
+ SetPageWorkingset(page);
list_add(&page->lru, &l_inactive);
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6389e876c7a7..efab0fca0bb7 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1074,6 +1074,7 @@ const char * const vmstat_text[] = {
"nr_isolated_file",
"workingset_refault",
"workingset_activate",
+ "workingset_restore",
"workingset_nodereclaim",
"nr_anon_pages",
"nr_mapped",
diff --git a/mm/workingset.c b/mm/workingset.c
index a1d3ccf1cd24..44ac09bf92fd 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -121,7 +121,7 @@
* the only thing eating into inactive list space is active pages.
*
*
- * Activating refaulting pages
+ * Refaulting inactive pages
*
* All that is known about the active list is that the pages have been
* accessed more than once in the past. This means that at any given
@@ -134,6 +134,10 @@
* used less frequently than the refaulting page - or even not used at
* all anymore.
*
+ * That means if inactive cache is refaulting with a suitable refault
+ * distance, we assume the cache workingset is transitioning and put
+ * pressure on the current active list.
+ *
* If this is wrong and demotion kicks in, the pages which are truly
* used more frequently will be reactivated while the less frequently
* used once will be evicted from memory.
@@ -141,6 +145,14 @@
* But if this is right, the stale pages will be pushed out of memory
* and the used pages get to stay in cache.
*
+ * Refaulting active pages
+ *
+ * If on the other hand the refaulting pages have recently been
+ * deactivated, it means that the active list is no longer protecting
+ * actively used cache from reclaim. The cache is NOT transitioning to
+ * a different workingset; the existing workingset is thrashing in the
+ * space allocated to the page cache.
+ *
*
* Implementation
*
@@ -156,8 +168,7 @@
*/
#define EVICTION_SHIFT (RADIX_TREE_EXCEPTIONAL_ENTRY + \
- NODES_SHIFT + \
- MEM_CGROUP_ID_SHIFT)
+ 1 + NODES_SHIFT + MEM_CGROUP_ID_SHIFT)
#define EVICTION_MASK (~0UL >> EVICTION_SHIFT)
/*
@@ -170,23 +181,28 @@
*/
static unsigned int bucket_order __read_mostly;
-static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction)
+static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction,
+ bool workingset)
{
eviction >>= bucket_order;
eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid;
eviction = (eviction << NODES_SHIFT) | pgdat->node_id;
+ eviction = (eviction << 1) | workingset;
eviction = (eviction << RADIX_TREE_EXCEPTIONAL_SHIFT);
return (void *)(eviction | RADIX_TREE_EXCEPTIONAL_ENTRY);
}
static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
- unsigned long *evictionp)
+ unsigned long *evictionp, bool *workingsetp)
{
unsigned long entry = (unsigned long)shadow;
int memcgid, nid;
+ bool workingset;
entry >>= RADIX_TREE_EXCEPTIONAL_SHIFT;
+ workingset = entry & 1;
+ entry >>= 1;
nid = entry & ((1UL << NODES_SHIFT) - 1);
entry >>= NODES_SHIFT;
memcgid = entry & ((1UL << MEM_CGROUP_ID_SHIFT) - 1);
@@ -195,6 +211,7 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
*memcgidp = memcgid;
*pgdat = NODE_DATA(nid);
*evictionp = entry << bucket_order;
+ *workingsetp = workingset;
}
/**
@@ -207,8 +224,8 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
*/
void *workingset_eviction(struct address_space *mapping, struct page *page)
{
- struct mem_cgroup *memcg = page_memcg(page);
struct pglist_data *pgdat = page_pgdat(page);
+ struct mem_cgroup *memcg = page_memcg(page);
int memcgid = mem_cgroup_id(memcg);
unsigned long eviction;
struct lruvec *lruvec;
@@ -220,30 +237,30 @@ void *workingset_eviction(struct address_space *mapping, struct page *page)
lruvec = mem_cgroup_lruvec(pgdat, memcg);
eviction = atomic_long_inc_return(&lruvec->inactive_age);
- return pack_shadow(memcgid, pgdat, eviction);
+ return pack_shadow(memcgid, pgdat, eviction, PageWorkingset(page));
}
/**
* workingset_refault - evaluate the refault of a previously evicted page
+ * @page: the freshly allocated replacement page
* @shadow: shadow entry of the evicted page
*
* Calculates and evaluates the refault distance of the previously
* evicted page in the context of the node it was allocated in.
- *
- * Returns %true if the page should be activated, %false otherwise.
*/
-bool workingset_refault(void *shadow)
+void workingset_refault(struct page *page, void *shadow)
{
unsigned long refault_distance;
+ struct pglist_data *pgdat;
unsigned long active_file;
struct mem_cgroup *memcg;
unsigned long eviction;
struct lruvec *lruvec;
unsigned long refault;
- struct pglist_data *pgdat;
+ bool workingset;
int memcgid;
- unpack_shadow(shadow, &memcgid, &pgdat, &eviction);
+ unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset);
rcu_read_lock();
/*
@@ -263,41 +280,51 @@ bool workingset_refault(void *shadow)
* configurations instead.
*/
memcg = mem_cgroup_from_id(memcgid);
- if (!mem_cgroup_disabled() && !memcg) {
- rcu_read_unlock();
- return false;
- }
+ if (!mem_cgroup_disabled() && !memcg)
+ goto out;
lruvec = mem_cgroup_lruvec(pgdat, memcg);
refault = atomic_long_read(&lruvec->inactive_age);
active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES);
/*
- * The unsigned subtraction here gives an accurate distance
- * across inactive_age overflows in most cases.
+ * Calculate the refault distance
*
- * There is a special case: usually, shadow entries have a
- * short lifetime and are either refaulted or reclaimed along
- * with the inode before they get too old. But it is not
- * impossible for the inactive_age to lap a shadow entry in
- * the field, which can then can result in a false small
- * refault distance, leading to a false activation should this
- * old entry actually refault again. However, earlier kernels
- * used to deactivate unconditionally with *every* reclaim
- * invocation for the longest time, so the occasional
- * inappropriate activation leading to pressure on the active
- * list is not a problem.
+ * The unsigned subtraction here gives an accurate distance
+ * across inactive_age overflows in most cases. There is a
+ * special case: usually, shadow entries have a short lifetime
+ * and are either refaulted or reclaimed along with the inode
+ * before they get too old. But it is not impossible for the
+ * inactive_age to lap a shadow entry in the field, which can
+ * then result in a false small refault distance, leading to a
+ * false activation should this old entry actually refault
+ * again. However, earlier kernels used to deactivate
+ * unconditionally with *every* reclaim invocation for the
+ * longest time, so the occasional inappropriate activation
+ * leading to pressure on the active list is not a problem.
*/
refault_distance = (refault - eviction) & EVICTION_MASK;
inc_lruvec_state(lruvec, WORKINGSET_REFAULT);
- if (refault_distance <= active_file) {
- inc_lruvec_state(lruvec, WORKINGSET_ACTIVATE);
- rcu_read_unlock();
- return true;
+ /*
+ * Compare the distance to the existing workingset size. We
+ * don't act on pages that couldn't stay resident even if all
+ * the memory was available to the page cache.
+ */
+ if (refault_distance > active_file)
+ goto out;
+
+ SetPageActive(page);
+ atomic_long_inc(&lruvec->inactive_age);
+ inc_lruvec_state(lruvec, WORKINGSET_ACTIVATE);
+
+ /* Page was active prior to eviction */
+ if (workingset) {
+ SetPageWorkingset(page);
+ inc_lruvec_state(lruvec, WORKINGSET_RESTORE);
}
+out:
rcu_read_unlock();
- return false;
}
/**
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 03/11] delayacct: track delays from thrashing cache pages
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
2019-03-12 10:19 ` [stable-4.14 01/11] mm: workingset: don't drop refault information prematurely Jack Wang
2019-03-12 10:19 ` [stable-4.14 02/11] mm: workingset: tell cache transitions from workingset thrashing Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 10:19 ` [stable-4.14 04/11] sched: loadavg: consolidate LOAD_INT, LOAD_FRAC, CALC_LOAD Jack Wang
` (8 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Tejun Heo, Vinayak Menon, Andrew Morton,
Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
Delay accounting already measures the time a task spends in direct reclaim
and waiting for swapin, but in low memory situations tasks spend can spend
a significant amount of their time waiting on thrashing page cache. This
isn't tracked right now.
To know the full impact of memory contention on an individual task,
measure the delay when waiting for a recently evicted active cache page to
read back into memory.
Also update tools/accounting/getdelays.c:
[hannes@computer accounting]$ sudo ./getdelays -d -p 1
print delayacct stats ON
PID 1
CPU count real total virtual total delay total delay average
50318 745000000 847346785 400533713 0.008ms
IO count delay total delay average
435 122601218 0ms
SWAP count delay total delay average
0 0 0ms
RECLAIM count delay total delay average
0 0 0ms
THRASHING count delay total delay average
19 12621439 0ms
Link: http://lkml.kernel.org/r/20180828172258.3185-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit daf3543d3da2e15e84f385a437ec113267512555)
[jwang: use raw_spin_lock]
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Conflicts:
kernel/delayacct.c
---
include/linux/delayacct.h | 23 +++++++++++++++++++++++
include/uapi/linux/taskstats.h | 6 +++++-
kernel/delayacct.c | 15 +++++++++++++++
mm/filemap.c | 11 +++++++++++
tools/accounting/getdelays.c | 8 +++++++-
5 files changed, 61 insertions(+), 2 deletions(-)
diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 31c865d1842e..577d1b25fccd 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -57,7 +57,12 @@ struct task_delay_info {
u64 freepages_start;
u64 freepages_delay; /* wait for memory reclaim */
+
+ u64 thrashing_start;
+ u64 thrashing_delay; /* wait for thrashing page */
+
u32 freepages_count; /* total count of memory reclaim */
+ u32 thrashing_count; /* total count of thrash waits */
};
#endif
@@ -76,6 +81,8 @@ extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
extern __u64 __delayacct_blkio_ticks(struct task_struct *);
extern void __delayacct_freepages_start(void);
extern void __delayacct_freepages_end(void);
+extern void __delayacct_thrashing_start(void);
+extern void __delayacct_thrashing_end(void);
static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
{
@@ -156,6 +163,18 @@ static inline void delayacct_freepages_end(void)
__delayacct_freepages_end();
}
+static inline void delayacct_thrashing_start(void)
+{
+ if (current->delays)
+ __delayacct_thrashing_start();
+}
+
+static inline void delayacct_thrashing_end(void)
+{
+ if (current->delays)
+ __delayacct_thrashing_end();
+}
+
#else
static inline void delayacct_set_flag(int flag)
{}
@@ -182,6 +201,10 @@ static inline void delayacct_freepages_start(void)
{}
static inline void delayacct_freepages_end(void)
{}
+static inline void delayacct_thrashing_start(void)
+{}
+static inline void delayacct_thrashing_end(void)
+{}
#endif /* CONFIG_TASK_DELAY_ACCT */
diff --git a/include/uapi/linux/taskstats.h b/include/uapi/linux/taskstats.h
index b7aa7bb2349f..5e8ca16a9079 100644
--- a/include/uapi/linux/taskstats.h
+++ b/include/uapi/linux/taskstats.h
@@ -34,7 +34,7 @@
*/
-#define TASKSTATS_VERSION 8
+#define TASKSTATS_VERSION 9
#define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN
* in linux/sched.h */
@@ -164,6 +164,10 @@ struct taskstats {
/* Delay waiting for memory reclaim */
__u64 freepages_count;
__u64 freepages_delay_total;
+
+ /* Delay waiting for thrashing page */
+ __u64 thrashing_count;
+ __u64 thrashing_delay_total;
};
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index ca8ac2824f0b..2a12b988c717 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -135,9 +135,12 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
tmp = d->freepages_delay_total + tsk->delays->freepages_delay;
d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;
+ tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;
+ d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;
d->blkio_count += tsk->delays->blkio_count;
d->swapin_count += tsk->delays->swapin_count;
d->freepages_count += tsk->delays->freepages_count;
+ d->thrashing_count += tsk->delays->thrashing_count;
raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
return 0;
@@ -169,3 +172,15 @@ void __delayacct_freepages_end(void)
¤t->delays->freepages_count);
}
+void __delayacct_thrashing_start(void)
+{
+ current->delays->thrashing_start = ktime_get_ns();
+}
+
+void __delayacct_thrashing_end(void)
+{
+ delayacct_end(¤t->delays->lock,
+ ¤t->delays->thrashing_start,
+ ¤t->delays->thrashing_delay,
+ ¤t->delays->thrashing_count);
+}
diff --git a/mm/filemap.c b/mm/filemap.c
index 9f995985e12f..51ed20eb2f2b 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -36,6 +36,7 @@
#include <linux/memcontrol.h>
#include <linux/cleancache.h>
#include <linux/rmap.h>
+#include <linux/delayacct.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
@@ -975,8 +976,15 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
{
struct wait_page_queue wait_page;
wait_queue_entry_t *wait = &wait_page.wait;
+ bool thrashing = false;
int ret = 0;
+ if (bit_nr == PG_locked && !PageSwapBacked(page) &&
+ !PageUptodate(page) && PageWorkingset(page)) {
+ delayacct_thrashing_start();
+ thrashing = true;
+ }
+
init_wait(wait);
wait->flags = lock ? WQ_FLAG_EXCLUSIVE : 0;
wait->func = wake_page_function;
@@ -1015,6 +1023,9 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
finish_wait(q, wait);
+ if (thrashing)
+ delayacct_thrashing_end();
+
/*
* A signal could leave PageWaiters set. Clearing it here if
* !waitqueue_active would be possible (by open-coding finish_wait),
diff --git a/tools/accounting/getdelays.c b/tools/accounting/getdelays.c
index 9f420d98b5fb..8cb504d30384 100644
--- a/tools/accounting/getdelays.c
+++ b/tools/accounting/getdelays.c
@@ -203,6 +203,8 @@ static void print_delayacct(struct taskstats *t)
"SWAP %15s%15s%15s\n"
" %15llu%15llu%15llums\n"
"RECLAIM %12s%15s%15s\n"
+ " %15llu%15llu%15llums\n"
+ "THRASHING%12s%15s%15s\n"
" %15llu%15llu%15llums\n",
"count", "real total", "virtual total",
"delay total", "delay average",
@@ -222,7 +224,11 @@ static void print_delayacct(struct taskstats *t)
"count", "delay total", "delay average",
(unsigned long long)t->freepages_count,
(unsigned long long)t->freepages_delay_total,
- average_ms(t->freepages_delay_total, t->freepages_count));
+ average_ms(t->freepages_delay_total, t->freepages_count),
+ "count", "delay total", "delay average",
+ (unsigned long long)t->thrashing_count,
+ (unsigned long long)t->thrashing_delay_total,
+ average_ms(t->thrashing_delay_total, t->thrashing_count));
}
static void task_context_switch_counts(struct taskstats *t)
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 04/11] sched: loadavg: consolidate LOAD_INT, LOAD_FRAC, CALC_LOAD
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (2 preceding siblings ...)
2019-03-12 10:19 ` [stable-4.14 03/11] delayacct: track delays from thrashing cache pages Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 10:19 ` [stable-4.14 05/11] sched: loadavg: make calc_load_n() public Jack Wang
` (7 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Tejun Heo, Vinayak Menon, Andrew Morton,
Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
There are several definitions of those functions/macros in places that
mess with fixed-point load averages. Provide an official version.
[akpm@linux-foundation.org: fix missed conversion in block/blk-iolatency.c]
Link: http://lkml.kernel.org/r/20180828172258.3185-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 5fc05f18905a39f2809484541ec75b1c1c501ef9)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
.../platforms/cell/cpufreq_spudemand.c | 2 +-
arch/powerpc/platforms/cell/spufs/sched.c | 9 +++-----
arch/s390/appldata/appldata_os.c | 4 ----
| 4 ----
fs/proc/loadavg.c | 3 ---
include/linux/sched/loadavg.h | 21 +++++++++++++++----
kernel/debug/kdb/kdb_main.c | 7 +------
kernel/sched/loadavg.c | 15 -------------
8 files changed, 22 insertions(+), 43 deletions(-)
diff --git a/arch/powerpc/platforms/cell/cpufreq_spudemand.c b/arch/powerpc/platforms/cell/cpufreq_spudemand.c
index 882944c36ef5..5d8e8b6bb1cc 100644
--- a/arch/powerpc/platforms/cell/cpufreq_spudemand.c
+++ b/arch/powerpc/platforms/cell/cpufreq_spudemand.c
@@ -49,7 +49,7 @@ static int calc_freq(struct spu_gov_info_struct *info)
cpu = info->policy->cpu;
busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus);
- CALC_LOAD(info->busy_spus, EXP, busy_spus * FIXED_1);
+ info->busy_spus = calc_load(info->busy_spus, EXP, busy_spus * FIXED_1);
pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n",
cpu, busy_spus, info->busy_spus);
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 1fbb5da17dd2..509cf6709131 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -987,9 +987,9 @@ static void spu_calc_load(void)
unsigned long active_tasks; /* fixed-point */
active_tasks = count_active_contexts() * FIXED_1;
- CALC_LOAD(spu_avenrun[0], EXP_1, active_tasks);
- CALC_LOAD(spu_avenrun[1], EXP_5, active_tasks);
- CALC_LOAD(spu_avenrun[2], EXP_15, active_tasks);
+ spu_avenrun[0] = calc_load(spu_avenrun[0], EXP_1, active_tasks);
+ spu_avenrun[1] = calc_load(spu_avenrun[1], EXP_5, active_tasks);
+ spu_avenrun[2] = calc_load(spu_avenrun[2], EXP_15, active_tasks);
}
static void spusched_wake(unsigned long data)
@@ -1071,9 +1071,6 @@ void spuctx_switch_state(struct spu_context *ctx,
}
}
-#define LOAD_INT(x) ((x) >> FSHIFT)
-#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
-
static int show_spu_loadavg(struct seq_file *s, void *private)
{
int a, b, c;
diff --git a/arch/s390/appldata/appldata_os.c b/arch/s390/appldata/appldata_os.c
index 45b3178200ab..a8aac17e1e82 100644
--- a/arch/s390/appldata/appldata_os.c
+++ b/arch/s390/appldata/appldata_os.c
@@ -24,10 +24,6 @@
#include "appldata.h"
-
-#define LOAD_INT(x) ((x) >> FSHIFT)
-#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
-
/*
* OS data
*
--git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 48eaf2879228..b459d5680a0c 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -132,10 +132,6 @@ struct menu_device {
int interval_ptr;
};
-
-#define LOAD_INT(x) ((x) >> FSHIFT)
-#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
-
static inline int get_loadavg(unsigned long load)
{
return LOAD_INT(load) * 10 + LOAD_FRAC(load) / 10;
diff --git a/fs/proc/loadavg.c b/fs/proc/loadavg.c
index 9bc5c58c00ee..b3c0475f88de 100644
--- a/fs/proc/loadavg.c
+++ b/fs/proc/loadavg.c
@@ -10,9 +10,6 @@
#include <linux/seqlock.h>
#include <linux/time.h>
-#define LOAD_INT(x) ((x) >> FSHIFT)
-#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
-
static int loadavg_proc_show(struct seq_file *m, void *v)
{
unsigned long avnrun[3];
diff --git a/include/linux/sched/loadavg.h b/include/linux/sched/loadavg.h
index 80bc84ba5d2a..cc9cc62bb1f8 100644
--- a/include/linux/sched/loadavg.h
+++ b/include/linux/sched/loadavg.h
@@ -22,10 +22,23 @@ extern void get_avenrun(unsigned long *loads, unsigned long offset, int shift);
#define EXP_5 2014 /* 1/exp(5sec/5min) */
#define EXP_15 2037 /* 1/exp(5sec/15min) */
-#define CALC_LOAD(load,exp,n) \
- load *= exp; \
- load += n*(FIXED_1-exp); \
- load >>= FSHIFT;
+/*
+ * a1 = a0 * e + a * (1 - e)
+ */
+static inline unsigned long
+calc_load(unsigned long load, unsigned long exp, unsigned long active)
+{
+ unsigned long newload;
+
+ newload = load * exp + active * (FIXED_1 - exp);
+ if (active >= load)
+ newload += FIXED_1-1;
+
+ return newload / FIXED_1;
+}
+
+#define LOAD_INT(x) ((x) >> FSHIFT)
+#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
extern void calc_global_load(unsigned long ticks);
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 993db6b2348e..3083df2a783e 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -2586,16 +2586,11 @@ static int kdb_summary(int argc, const char **argv)
}
kdb_printf("%02ld:%02ld\n", val.uptime/(60*60), (val.uptime/60)%60);
- /* lifted from fs/proc/proc_misc.c::loadavg_read_proc() */
-
-#define LOAD_INT(x) ((x) >> FSHIFT)
-#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
kdb_printf("load avg %ld.%02ld %ld.%02ld %ld.%02ld\n",
LOAD_INT(val.loads[0]), LOAD_FRAC(val.loads[0]),
LOAD_INT(val.loads[1]), LOAD_FRAC(val.loads[1]),
LOAD_INT(val.loads[2]), LOAD_FRAC(val.loads[2]));
-#undef LOAD_INT
-#undef LOAD_FRAC
+
/* Display in kilobytes */
#define K(x) ((x) << (PAGE_SHIFT - 10))
kdb_printf("\nMemTotal: %8lu kB\nMemFree: %8lu kB\n"
diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
index 89a989e4d758..d37eb9fe8aa8 100644
--- a/kernel/sched/loadavg.c
+++ b/kernel/sched/loadavg.c
@@ -95,21 +95,6 @@ long calc_load_fold_active(struct rq *this_rq, long adjust)
return delta;
}
-/*
- * a1 = a0 * e + a * (1 - e)
- */
-static unsigned long
-calc_load(unsigned long load, unsigned long exp, unsigned long active)
-{
- unsigned long newload;
-
- newload = load * exp + active * (FIXED_1 - exp);
- if (active >= load)
- newload += FIXED_1-1;
-
- return newload / FIXED_1;
-}
-
#ifdef CONFIG_NO_HZ_COMMON
/*
* Handle NO_HZ for the global load-average.
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 05/11] sched: loadavg: make calc_load_n() public
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (3 preceding siblings ...)
2019-03-12 10:19 ` [stable-4.14 04/11] sched: loadavg: consolidate LOAD_INT, LOAD_FRAC, CALC_LOAD Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 10:19 ` [stable-4.14 06/11] sched: sched.h: make rq locking and clock functions available in stats.h Jack Wang
` (6 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Tejun Heo, Vinayak Menon, Andrew Morton,
Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
It's going to be used in a later patch. Keep the churn separate.
Link: http://lkml.kernel.org/r/20180828172258.3185-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit b56b064dcf9358d4d5869130483c4e2d0ff5df6f)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
include/linux/sched/loadavg.h | 3 +
kernel/sched/loadavg.c | 138 +++++++++++++++++-----------------
2 files changed, 72 insertions(+), 69 deletions(-)
diff --git a/include/linux/sched/loadavg.h b/include/linux/sched/loadavg.h
index cc9cc62bb1f8..4859bea47a7b 100644
--- a/include/linux/sched/loadavg.h
+++ b/include/linux/sched/loadavg.h
@@ -37,6 +37,9 @@ calc_load(unsigned long load, unsigned long exp, unsigned long active)
return newload / FIXED_1;
}
+extern unsigned long calc_load_n(unsigned long load, unsigned long exp,
+ unsigned long active, unsigned int n);
+
#define LOAD_INT(x) ((x) >> FSHIFT)
#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
index d37eb9fe8aa8..73157e882918 100644
--- a/kernel/sched/loadavg.c
+++ b/kernel/sched/loadavg.c
@@ -95,6 +95,75 @@ long calc_load_fold_active(struct rq *this_rq, long adjust)
return delta;
}
+/**
+ * fixed_power_int - compute: x^n, in O(log n) time
+ *
+ * @x: base of the power
+ * @frac_bits: fractional bits of @x
+ * @n: power to raise @x to.
+ *
+ * By exploiting the relation between the definition of the natural power
+ * function: x^n := x*x*...*x (x multiplied by itself for n times), and
+ * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
+ * (where: n_i \elem {0, 1}, the binary vector representing n),
+ * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
+ * of course trivially computable in O(log_2 n), the length of our binary
+ * vector.
+ */
+static unsigned long
+fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n)
+{
+ unsigned long result = 1UL << frac_bits;
+
+ if (n) {
+ for (;;) {
+ if (n & 1) {
+ result *= x;
+ result += 1UL << (frac_bits - 1);
+ result >>= frac_bits;
+ }
+ n >>= 1;
+ if (!n)
+ break;
+ x *= x;
+ x += 1UL << (frac_bits - 1);
+ x >>= frac_bits;
+ }
+ }
+
+ return result;
+}
+
+/*
+ * a1 = a0 * e + a * (1 - e)
+ *
+ * a2 = a1 * e + a * (1 - e)
+ * = (a0 * e + a * (1 - e)) * e + a * (1 - e)
+ * = a0 * e^2 + a * (1 - e) * (1 + e)
+ *
+ * a3 = a2 * e + a * (1 - e)
+ * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
+ * = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
+ *
+ * ...
+ *
+ * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
+ * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
+ * = a0 * e^n + a * (1 - e^n)
+ *
+ * [1] application of the geometric series:
+ *
+ * n 1 - x^(n+1)
+ * S_n := \Sum x^i = -------------
+ * i=0 1 - x
+ */
+unsigned long
+calc_load_n(unsigned long load, unsigned long exp,
+ unsigned long active, unsigned int n)
+{
+ return calc_load(load, fixed_power_int(exp, FSHIFT, n), active);
+}
+
#ifdef CONFIG_NO_HZ_COMMON
/*
* Handle NO_HZ for the global load-average.
@@ -214,75 +283,6 @@ static long calc_load_nohz_fold(void)
return delta;
}
-/**
- * fixed_power_int - compute: x^n, in O(log n) time
- *
- * @x: base of the power
- * @frac_bits: fractional bits of @x
- * @n: power to raise @x to.
- *
- * By exploiting the relation between the definition of the natural power
- * function: x^n := x*x*...*x (x multiplied by itself for n times), and
- * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
- * (where: n_i \elem {0, 1}, the binary vector representing n),
- * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
- * of course trivially computable in O(log_2 n), the length of our binary
- * vector.
- */
-static unsigned long
-fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n)
-{
- unsigned long result = 1UL << frac_bits;
-
- if (n) {
- for (;;) {
- if (n & 1) {
- result *= x;
- result += 1UL << (frac_bits - 1);
- result >>= frac_bits;
- }
- n >>= 1;
- if (!n)
- break;
- x *= x;
- x += 1UL << (frac_bits - 1);
- x >>= frac_bits;
- }
- }
-
- return result;
-}
-
-/*
- * a1 = a0 * e + a * (1 - e)
- *
- * a2 = a1 * e + a * (1 - e)
- * = (a0 * e + a * (1 - e)) * e + a * (1 - e)
- * = a0 * e^2 + a * (1 - e) * (1 + e)
- *
- * a3 = a2 * e + a * (1 - e)
- * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
- * = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
- *
- * ...
- *
- * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
- * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
- * = a0 * e^n + a * (1 - e^n)
- *
- * [1] application of the geometric series:
- *
- * n 1 - x^(n+1)
- * S_n := \Sum x^i = -------------
- * i=0 1 - x
- */
-static unsigned long
-calc_load_n(unsigned long load, unsigned long exp,
- unsigned long active, unsigned int n)
-{
- return calc_load(load, fixed_power_int(exp, FSHIFT, n), active);
-}
-
/*
* NO_HZ can leave us missing all per-cpu ticks calling
* calc_load_fold_active(), but since a NO_HZ CPU folds its delta into
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 06/11] sched: sched.h: make rq locking and clock functions available in stats.h
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (4 preceding siblings ...)
2019-03-12 10:19 ` [stable-4.14 05/11] sched: loadavg: make calc_load_n() public Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 10:19 ` [stable-4.14 07/11] sched: introduce this_rq_lock_irq() Jack Wang
` (5 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Tejun Heo, Vinayak Menon, Andrew Morton,
Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
kernel/sched/sched.h includes "stats.h" half-way through the file. The
next patch introduces users of sched.h's rq locking functions and
update_rq_clock() in kernel/sched/stats.h. Move those definitions up in
the file so they are available in stats.h.
Link: http://lkml.kernel.org/r/20180828172258.3185-7-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 69d22d2b3563701686c4b97b3c1c8a00238f7d13)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Conflicts:
kernel/sched/sched.h
---
kernel/sched/sched.h | 164 +++++++++++++++++++++----------------------
1 file changed, 82 insertions(+), 82 deletions(-)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 452b56923c6d..5ea86c072c07 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -848,6 +848,8 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
#define raw_rq() raw_cpu_ptr(&runqueues)
+extern void update_rq_clock(struct rq *rq);
+
static inline u64 __rq_clock_broken(struct rq *rq)
{
return READ_ONCE(rq->clock);
@@ -959,6 +961,86 @@ static inline void rq_repin_lock(struct rq *rq, struct rq_flags *rf)
#endif
}
+struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
+ __acquires(rq->lock);
+
+struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
+ __acquires(p->pi_lock)
+ __acquires(rq->lock);
+
+static inline void __task_rq_unlock(struct rq *rq, struct rq_flags *rf)
+ __releases(rq->lock)
+{
+ rq_unpin_lock(rq, rf);
+ raw_spin_unlock(&rq->lock);
+}
+
+static inline void
+task_rq_unlock(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
+ __releases(rq->lock)
+ __releases(p->pi_lock)
+{
+ rq_unpin_lock(rq, rf);
+ raw_spin_unlock(&rq->lock);
+ raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
+}
+
+static inline void
+rq_lock_irqsave(struct rq *rq, struct rq_flags *rf)
+ __acquires(rq->lock)
+{
+ raw_spin_lock_irqsave(&rq->lock, rf->flags);
+ rq_pin_lock(rq, rf);
+}
+
+static inline void
+rq_lock_irq(struct rq *rq, struct rq_flags *rf)
+ __acquires(rq->lock)
+{
+ raw_spin_lock_irq(&rq->lock);
+ rq_pin_lock(rq, rf);
+}
+
+static inline void
+rq_lock(struct rq *rq, struct rq_flags *rf)
+ __acquires(rq->lock)
+{
+ raw_spin_lock(&rq->lock);
+ rq_pin_lock(rq, rf);
+}
+
+static inline void
+rq_relock(struct rq *rq, struct rq_flags *rf)
+ __acquires(rq->lock)
+{
+ raw_spin_lock(&rq->lock);
+ rq_repin_lock(rq, rf);
+}
+
+static inline void
+rq_unlock_irqrestore(struct rq *rq, struct rq_flags *rf)
+ __releases(rq->lock)
+{
+ rq_unpin_lock(rq, rf);
+ raw_spin_unlock_irqrestore(&rq->lock, rf->flags);
+}
+
+static inline void
+rq_unlock_irq(struct rq *rq, struct rq_flags *rf)
+ __releases(rq->lock)
+{
+ rq_unpin_lock(rq, rf);
+ raw_spin_unlock_irq(&rq->lock);
+}
+
+static inline void
+rq_unlock(struct rq *rq, struct rq_flags *rf)
+ __releases(rq->lock)
+{
+ rq_unpin_lock(rq, rf);
+ raw_spin_unlock(&rq->lock);
+}
+
#ifdef CONFIG_NUMA
enum numa_topology_type {
NUMA_DIRECT,
@@ -1623,8 +1705,6 @@ static inline void rq_last_tick_reset(struct rq *rq)
#endif
}
-extern void update_rq_clock(struct rq *rq);
-
extern void activate_task(struct rq *rq, struct task_struct *p, int flags);
extern void deactivate_task(struct rq *rq, struct task_struct *p, int flags);
@@ -1698,86 +1778,6 @@ static inline void sched_rt_avg_update(struct rq *rq, u64 rt_delta) { }
static inline void sched_avg_update(struct rq *rq) { }
#endif
-struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
- __acquires(rq->lock);
-
-struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
- __acquires(p->pi_lock)
- __acquires(rq->lock);
-
-static inline void __task_rq_unlock(struct rq *rq, struct rq_flags *rf)
- __releases(rq->lock)
-{
- rq_unpin_lock(rq, rf);
- raw_spin_unlock(&rq->lock);
-}
-
-static inline void
-task_rq_unlock(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
- __releases(rq->lock)
- __releases(p->pi_lock)
-{
- rq_unpin_lock(rq, rf);
- raw_spin_unlock(&rq->lock);
- raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
-}
-
-static inline void
-rq_lock_irqsave(struct rq *rq, struct rq_flags *rf)
- __acquires(rq->lock)
-{
- raw_spin_lock_irqsave(&rq->lock, rf->flags);
- rq_pin_lock(rq, rf);
-}
-
-static inline void
-rq_lock_irq(struct rq *rq, struct rq_flags *rf)
- __acquires(rq->lock)
-{
- raw_spin_lock_irq(&rq->lock);
- rq_pin_lock(rq, rf);
-}
-
-static inline void
-rq_lock(struct rq *rq, struct rq_flags *rf)
- __acquires(rq->lock)
-{
- raw_spin_lock(&rq->lock);
- rq_pin_lock(rq, rf);
-}
-
-static inline void
-rq_relock(struct rq *rq, struct rq_flags *rf)
- __acquires(rq->lock)
-{
- raw_spin_lock(&rq->lock);
- rq_repin_lock(rq, rf);
-}
-
-static inline void
-rq_unlock_irqrestore(struct rq *rq, struct rq_flags *rf)
- __releases(rq->lock)
-{
- rq_unpin_lock(rq, rf);
- raw_spin_unlock_irqrestore(&rq->lock, rf->flags);
-}
-
-static inline void
-rq_unlock_irq(struct rq *rq, struct rq_flags *rf)
- __releases(rq->lock)
-{
- rq_unpin_lock(rq, rf);
- raw_spin_unlock_irq(&rq->lock);
-}
-
-static inline void
-rq_unlock(struct rq *rq, struct rq_flags *rf)
- __releases(rq->lock)
-{
- rq_unpin_lock(rq, rf);
- raw_spin_unlock(&rq->lock);
-}
-
#ifdef CONFIG_SMP
#ifdef CONFIG_PREEMPT
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 07/11] sched: introduce this_rq_lock_irq()
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (5 preceding siblings ...)
2019-03-12 10:19 ` [stable-4.14 06/11] sched: sched.h: make rq locking and clock functions available in stats.h Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 10:19 ` [stable-4.14 08/11] psi: pressure stall information for CPU, memory, and IO Jack Wang
` (4 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Tejun Heo, Vinayak Menon, Andrew Morton,
Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
do_sched_yield() disables IRQs, looks up this_rq() and locks it. The next
patch is adding another site with the same pattern, so provide a
convenience function for it.
Link: http://lkml.kernel.org/r/20180828172258.3185-8-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit d7edeb7f6a545695f064ce3787689f85e1e8b6dd)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
kernel/sched/core.c | 4 +---
kernel/sched/sched.h | 12 ++++++++++++
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0552ddbb25e2..a0b7e66c7281 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4817,9 +4817,7 @@ SYSCALL_DEFINE0(sched_yield)
struct rq_flags rf;
struct rq *rq;
- local_irq_disable();
- rq = this_rq();
- rq_lock(rq, &rf);
+ rq = this_rq_lock_irq(&rf);
schedstat_inc(rq->yld_count);
current->sched_class->yield_task(rq);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 5ea86c072c07..e73d5d68602d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1041,6 +1041,18 @@ rq_unlock(struct rq *rq, struct rq_flags *rf)
raw_spin_unlock(&rq->lock);
}
+static inline struct rq *
+this_rq_lock_irq(struct rq_flags *rf)
+ __acquires(rq->lock)
+{
+ struct rq *rq;
+
+ local_irq_disable();
+ rq = this_rq();
+ rq_lock(rq, rf);
+ return rq;
+}
+
#ifdef CONFIG_NUMA
enum numa_topology_type {
NUMA_DIRECT,
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 08/11] psi: pressure stall information for CPU, memory, and IO
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (6 preceding siblings ...)
2019-03-12 10:19 ` [stable-4.14 07/11] sched: introduce this_rq_lock_irq() Jack Wang
@ 2019-03-12 10:19 ` Jack Wang
2019-03-12 10:20 ` [stable-4.14 09/11] psi: cgroup support Jack Wang
` (3 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:19 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Tejun Heo, Vinayak Menon, Andrew Morton,
Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills. In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.
In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.
A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively. Stall states are aggregate versions of the per-task delay
accounting delays:
cpu: some tasks are runnable but not executing on a CPU
memory: tasks are reclaiming, or waiting for swapin or thrashing cache
io: tasks are waiting for io completions
These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit. They can also indicate when the system
is approaching lockup scenarios and OOMs.
To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states. Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime. A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).
[hannes@cmpxchg.org: doc fixlet, per Randy]
Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit e8574dc1f30d2d7f10a64acab3c7d64f22f8e991)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Conflicts:
kernel/sched/Makefile
kernel/sched/sched.h
---
Documentation/accounting/psi.txt | 64 +++
include/linux/psi.h | 28 ++
include/linux/psi_types.h | 92 +++++
include/linux/sched.h | 10 +
init/Kconfig | 15 +
kernel/fork.c | 4 +
kernel/sched/Makefile | 1 +
kernel/sched/core.c | 12 +-
kernel/sched/psi.c | 657 +++++++++++++++++++++++++++++++
kernel/sched/sched.h | 3 +
kernel/sched/stats.h | 86 ++++
mm/compaction.c | 5 +
mm/filemap.c | 15 +-
mm/page_alloc.c | 9 +
mm/vmscan.c | 11 +
15 files changed, 1006 insertions(+), 6 deletions(-)
create mode 100644 Documentation/accounting/psi.txt
create mode 100644 include/linux/psi.h
create mode 100644 include/linux/psi_types.h
create mode 100644 kernel/sched/psi.c
diff --git a/Documentation/accounting/psi.txt b/Documentation/accounting/psi.txt
new file mode 100644
index 000000000000..3753a82f1cf5
--- /dev/null
+++ b/Documentation/accounting/psi.txt
@@ -0,0 +1,64 @@
+================================
+PSI - Pressure Stall Information
+================================
+
+:Date: April, 2018
+:Author: Johannes Weiner <hannes@cmpxchg.org>
+
+When CPU, memory or IO devices are contended, workloads experience
+latency spikes, throughput losses, and run the risk of OOM kills.
+
+Without an accurate measure of such contention, users are forced to
+either play it safe and under-utilize their hardware resources, or
+roll the dice and frequently suffer the disruptions resulting from
+excessive overcommit.
+
+The psi feature identifies and quantifies the disruptions caused by
+such resource crunches and the time impact it has on complex workloads
+or even entire systems.
+
+Having an accurate measure of productivity losses caused by resource
+scarcity aids users in sizing workloads to hardware--or provisioning
+hardware according to workload demand.
+
+As psi aggregates this information in realtime, systems can be managed
+dynamically using techniques such as load shedding, migrating jobs to
+other systems or data centers, or strategically pausing or killing low
+priority or restartable batch jobs.
+
+This allows maximizing hardware utilization without sacrificing
+workload health or risking major disruptions such as OOM kills.
+
+Pressure interface
+==================
+
+Pressure information for each resource is exported through the
+respective file in /proc/pressure/ -- cpu, memory, and io.
+
+The format for CPU is as such:
+
+some avg10=0.00 avg60=0.00 avg300=0.00 total=0
+
+and for memory and IO:
+
+some avg10=0.00 avg60=0.00 avg300=0.00 total=0
+full avg10=0.00 avg60=0.00 avg300=0.00 total=0
+
+The "some" line indicates the share of time in which at least some
+tasks are stalled on a given resource.
+
+The "full" line indicates the share of time in which all non-idle
+tasks are stalled on a given resource simultaneously. In this state
+actual CPU cycles are going to waste, and a workload that spends
+extended time in this state is considered to be thrashing. This has
+severe impact on performance, and it's useful to distinguish this
+situation from a state where some tasks are stalled but the CPU is
+still doing productive work. As such, time spent in this subset of the
+stall state is tracked separately and exported in the "full" averages.
+
+The ratios are tracked as recent trends over ten, sixty, and three
+hundred second windows, which gives insight into short term events as
+well as medium and long term trends. The total absolute stall time is
+tracked and exported as well, to allow detection of latency spikes
+which wouldn't necessarily make a dent in the time averages, or to
+average trends over custom time frames.
diff --git a/include/linux/psi.h b/include/linux/psi.h
new file mode 100644
index 000000000000..b0daf050de58
--- /dev/null
+++ b/include/linux/psi.h
@@ -0,0 +1,28 @@
+#ifndef _LINUX_PSI_H
+#define _LINUX_PSI_H
+
+#include <linux/psi_types.h>
+#include <linux/sched.h>
+
+#ifdef CONFIG_PSI
+
+extern bool psi_disabled;
+
+void psi_init(void);
+
+void psi_task_change(struct task_struct *task, int clear, int set);
+
+void psi_memstall_tick(struct task_struct *task, int cpu);
+void psi_memstall_enter(unsigned long *flags);
+void psi_memstall_leave(unsigned long *flags);
+
+#else /* CONFIG_PSI */
+
+static inline void psi_init(void) {}
+
+static inline void psi_memstall_enter(unsigned long *flags) {}
+static inline void psi_memstall_leave(unsigned long *flags) {}
+
+#endif /* CONFIG_PSI */
+
+#endif /* _LINUX_PSI_H */
diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h
new file mode 100644
index 000000000000..2cf422db5d18
--- /dev/null
+++ b/include/linux/psi_types.h
@@ -0,0 +1,92 @@
+#ifndef _LINUX_PSI_TYPES_H
+#define _LINUX_PSI_TYPES_H
+
+#include <linux/seqlock.h>
+#include <linux/types.h>
+
+#ifdef CONFIG_PSI
+
+/* Tracked task states */
+enum psi_task_count {
+ NR_IOWAIT,
+ NR_MEMSTALL,
+ NR_RUNNING,
+ NR_PSI_TASK_COUNTS,
+};
+
+/* Task state bitmasks */
+#define TSK_IOWAIT (1 << NR_IOWAIT)
+#define TSK_MEMSTALL (1 << NR_MEMSTALL)
+#define TSK_RUNNING (1 << NR_RUNNING)
+
+/* Resources that workloads could be stalled on */
+enum psi_res {
+ PSI_IO,
+ PSI_MEM,
+ PSI_CPU,
+ NR_PSI_RESOURCES,
+};
+
+/*
+ * Pressure states for each resource:
+ *
+ * SOME: Stalled tasks & working tasks
+ * FULL: Stalled tasks & no working tasks
+ */
+enum psi_states {
+ PSI_IO_SOME,
+ PSI_IO_FULL,
+ PSI_MEM_SOME,
+ PSI_MEM_FULL,
+ PSI_CPU_SOME,
+ /* Only per-CPU, to weigh the CPU in the global average: */
+ PSI_NONIDLE,
+ NR_PSI_STATES,
+};
+
+struct psi_group_cpu {
+ /* 1st cacheline updated by the scheduler */
+
+ /* Aggregator needs to know of concurrent changes */
+ seqcount_t seq ____cacheline_aligned_in_smp;
+
+ /* States of the tasks belonging to this group */
+ unsigned int tasks[NR_PSI_TASK_COUNTS];
+
+ /* Period time sampling buckets for each state of interest (ns) */
+ u32 times[NR_PSI_STATES];
+
+ /* Time of last task change in this group (rq_clock) */
+ u64 state_start;
+
+ /* 2nd cacheline updated by the aggregator */
+
+ /* Delta detection against the sampling buckets */
+ u32 times_prev[NR_PSI_STATES] ____cacheline_aligned_in_smp;
+};
+
+struct psi_group {
+ /* Protects data updated during an aggregation */
+ struct mutex stat_lock;
+
+ /* Per-cpu task state & time tracking */
+ struct psi_group_cpu __percpu *pcpu;
+
+ /* Periodic aggregation state */
+ u64 total_prev[NR_PSI_STATES - 1];
+ u64 last_update;
+ u64 next_update;
+ struct delayed_work clock_work;
+
+ /* Total stall times and sampled pressure averages */
+ u64 total[NR_PSI_STATES - 1];
+ unsigned long avg[NR_PSI_STATES - 1][3];
+};
+
+#else /* CONFIG_PSI */
+
+struct psi_group { };
+
+#endif /* CONFIG_PSI */
+
+#endif /* _LINUX_PSI_TYPES_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 866439c361a9..abfa2ad97e19 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -25,6 +25,7 @@
#include <linux/latencytop.h>
#include <linux/sched/prio.h>
#include <linux/signal_types.h>
+#include <linux/psi_types.h>
#include <linux/mm_types_task.h>
#include <linux/task_io_accounting.h>
@@ -668,6 +669,10 @@ struct task_struct {
unsigned sched_contributes_to_load:1;
unsigned sched_migrated:1;
unsigned sched_remote_wakeup:1;
+#ifdef CONFIG_PSI
+ unsigned sched_psi_wake_requeue:1;
+#endif
+
/* Force alignment to the next boundary: */
unsigned :0;
@@ -926,6 +931,10 @@ struct task_struct {
siginfo_t *last_siginfo;
struct task_io_accounting ioac;
+#ifdef CONFIG_PSI
+ /* Pressure stall state */
+ unsigned int psi_flags;
+#endif
#ifdef CONFIG_TASK_XACCT
/* Accumulated RSS usage: */
u64 acct_rss_mem1;
@@ -1355,6 +1364,7 @@ extern struct pid *cad_pid;
#define PF_KTHREAD 0x00200000 /* I am a kernel thread */
#define PF_RANDOMIZE 0x00400000 /* Randomize virtual address space */
#define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */
+#define PF_MEMSTALL 0x01000000 /* Stalled due to lack of memory */
#define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_allowed */
#define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */
#define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */
diff --git a/init/Kconfig b/init/Kconfig
index 46075327c165..d19c853088c1 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -470,6 +470,21 @@ config TASK_IO_ACCOUNTING
Say N if unsure.
+config PSI
+ bool "Pressure stall information tracking"
+ help
+ Collect metrics that indicate how overcommitted the CPU, memory,
+ and IO capacity are in the system.
+
+ If you say Y here, the kernel will create /proc/pressure/ with the
+ pressure statistics files cpu, memory, and io. These will indicate
+ the share of walltime in which some or all tasks in the system are
+ delayed due to contention of the respective resource.
+
+ For more details see Documentation/accounting/psi.txt.
+
+ Say N if unsure.
+
endmenu # "CPU/Task time and stats accounting"
source "kernel/rcu/Kconfig"
diff --git a/kernel/fork.c b/kernel/fork.c
index 6d6ce2c3a364..b6df619c6e67 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1667,6 +1667,10 @@ static __latent_entropy struct task_struct *copy_process(
p->default_timer_slack_ns = current->timer_slack_ns;
+#ifdef CONFIG_PSI
+ p->psi_flags = 0;
+#endif
+
task_io_accounting_init(&p->ioac);
acct_clear_integrals(p);
diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index a9ee16bbc693..d996b71d6713 100644
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -27,3 +27,4 @@ obj-$(CONFIG_CGROUP_CPUACCT) += cpuacct.o
obj-$(CONFIG_CPU_FREQ) += cpufreq.o
obj-$(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) += cpufreq_schedutil.o
obj-$(CONFIG_MEMBARRIER) += membarrier.o
+obj-$(CONFIG_PSI) += psi.o
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a0b7e66c7281..7387ab03c40a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -756,8 +756,10 @@ static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
if (!(flags & ENQUEUE_NOCLOCK))
update_rq_clock(rq);
- if (!(flags & ENQUEUE_RESTORE))
+ if (!(flags & ENQUEUE_RESTORE)) {
sched_info_queued(rq, p);
+ psi_enqueue(p, flags & ENQUEUE_WAKEUP);
+ }
p->sched_class->enqueue_task(rq, p, flags);
}
@@ -767,8 +769,10 @@ static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
if (!(flags & DEQUEUE_NOCLOCK))
update_rq_clock(rq);
- if (!(flags & DEQUEUE_SAVE))
+ if (!(flags & DEQUEUE_SAVE)) {
sched_info_dequeued(rq, p);
+ psi_dequeue(p, flags & DEQUEUE_SLEEP);
+ }
p->sched_class->dequeue_task(rq, p, flags);
}
@@ -2071,6 +2075,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
if (task_cpu(p) != cpu) {
wake_flags |= WF_MIGRATED;
+ psi_ttwu_dequeue(p);
set_task_cpu(p, cpu);
}
@@ -3032,6 +3037,7 @@ void scheduler_tick(void)
curr->sched_class->task_tick(rq, curr, 0);
cpu_load_update_active(rq);
calc_global_load_tick(rq);
+ psi_task_tick(rq);
rq_unlock(rq, &rf);
@@ -5962,6 +5968,8 @@ void __init sched_init(void)
init_schedstats();
+ psi_init();
+
scheduler_running = 1;
}
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
new file mode 100644
index 000000000000..595414599b98
--- /dev/null
+++ b/kernel/sched/psi.c
@@ -0,0 +1,657 @@
+/*
+ * Pressure stall information for CPU, memory and IO
+ *
+ * Copyright (c) 2018 Facebook, Inc.
+ * Author: Johannes Weiner <hannes@cmpxchg.org>
+ *
+ * When CPU, memory and IO are contended, tasks experience delays that
+ * reduce throughput and introduce latencies into the workload. Memory
+ * and IO contention, in addition, can cause a full loss of forward
+ * progress in which the CPU goes idle.
+ *
+ * This code aggregates individual task delays into resource pressure
+ * metrics that indicate problems with both workload health and
+ * resource utilization.
+ *
+ * Model
+ *
+ * The time in which a task can execute on a CPU is our baseline for
+ * productivity. Pressure expresses the amount of time in which this
+ * potential cannot be realized due to resource contention.
+ *
+ * This concept of productivity has two components: the workload and
+ * the CPU. To measure the impact of pressure on both, we define two
+ * contention states for a resource: SOME and FULL.
+ *
+ * In the SOME state of a given resource, one or more tasks are
+ * delayed on that resource. This affects the workload's ability to
+ * perform work, but the CPU may still be executing other tasks.
+ *
+ * In the FULL state of a given resource, all non-idle tasks are
+ * delayed on that resource such that nobody is advancing and the CPU
+ * goes idle. This leaves both workload and CPU unproductive.
+ *
+ * (Naturally, the FULL state doesn't exist for the CPU resource.)
+ *
+ * SOME = nr_delayed_tasks != 0
+ * FULL = nr_delayed_tasks != 0 && nr_running_tasks == 0
+ *
+ * The percentage of wallclock time spent in those compound stall
+ * states gives pressure numbers between 0 and 100 for each resource,
+ * where the SOME percentage indicates workload slowdowns and the FULL
+ * percentage indicates reduced CPU utilization:
+ *
+ * %SOME = time(SOME) / period
+ * %FULL = time(FULL) / period
+ *
+ * Multiple CPUs
+ *
+ * The more tasks and available CPUs there are, the more work can be
+ * performed concurrently. This means that the potential that can go
+ * unrealized due to resource contention *also* scales with non-idle
+ * tasks and CPUs.
+ *
+ * Consider a scenario where 257 number crunching tasks are trying to
+ * run concurrently on 256 CPUs. If we simply aggregated the task
+ * states, we would have to conclude a CPU SOME pressure number of
+ * 100%, since *somebody* is waiting on a runqueue at all
+ * times. However, that is clearly not the amount of contention the
+ * workload is experiencing: only one out of 256 possible exceution
+ * threads will be contended at any given time, or about 0.4%.
+ *
+ * Conversely, consider a scenario of 4 tasks and 4 CPUs where at any
+ * given time *one* of the tasks is delayed due to a lack of memory.
+ * Again, looking purely at the task state would yield a memory FULL
+ * pressure number of 0%, since *somebody* is always making forward
+ * progress. But again this wouldn't capture the amount of execution
+ * potential lost, which is 1 out of 4 CPUs, or 25%.
+ *
+ * To calculate wasted potential (pressure) with multiple processors,
+ * we have to base our calculation on the number of non-idle tasks in
+ * conjunction with the number of available CPUs, which is the number
+ * of potential execution threads. SOME becomes then the proportion of
+ * delayed tasks to possibe threads, and FULL is the share of possible
+ * threads that are unproductive due to delays:
+ *
+ * threads = min(nr_nonidle_tasks, nr_cpus)
+ * SOME = min(nr_delayed_tasks / threads, 1)
+ * FULL = (threads - min(nr_running_tasks, threads)) / threads
+ *
+ * For the 257 number crunchers on 256 CPUs, this yields:
+ *
+ * threads = min(257, 256)
+ * SOME = min(1 / 256, 1) = 0.4%
+ * FULL = (256 - min(257, 256)) / 256 = 0%
+ *
+ * For the 1 out of 4 memory-delayed tasks, this yields:
+ *
+ * threads = min(4, 4)
+ * SOME = min(1 / 4, 1) = 25%
+ * FULL = (4 - min(3, 4)) / 4 = 25%
+ *
+ * [ Substitute nr_cpus with 1, and you can see that it's a natural
+ * extension of the single-CPU model. ]
+ *
+ * Implementation
+ *
+ * To assess the precise time spent in each such state, we would have
+ * to freeze the system on task changes and start/stop the state
+ * clocks accordingly. Obviously that doesn't scale in practice.
+ *
+ * Because the scheduler aims to distribute the compute load evenly
+ * among the available CPUs, we can track task state locally to each
+ * CPU and, at much lower frequency, extrapolate the global state for
+ * the cumulative stall times and the running averages.
+ *
+ * For each runqueue, we track:
+ *
+ * tSOME[cpu] = time(nr_delayed_tasks[cpu] != 0)
+ * tFULL[cpu] = time(nr_delayed_tasks[cpu] && !nr_running_tasks[cpu])
+ * tNONIDLE[cpu] = time(nr_nonidle_tasks[cpu] != 0)
+ *
+ * and then periodically aggregate:
+ *
+ * tNONIDLE = sum(tNONIDLE[i])
+ *
+ * tSOME = sum(tSOME[i] * tNONIDLE[i]) / tNONIDLE
+ * tFULL = sum(tFULL[i] * tNONIDLE[i]) / tNONIDLE
+ *
+ * %SOME = tSOME / period
+ * %FULL = tFULL / period
+ *
+ * This gives us an approximation of pressure that is practical
+ * cost-wise, yet way more sensitive and accurate than periodic
+ * sampling of the aggregate task states would be.
+ */
+
+#include <linux/sched/loadavg.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+#include <linux/seqlock.h>
+#include <linux/cgroup.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/psi.h>
+#include "sched.h"
+
+static int psi_bug __read_mostly;
+
+bool psi_disabled __read_mostly;
+core_param(psi_disabled, psi_disabled, bool, 0644);
+
+/* Running averages - we need to be higher-res than loadavg */
+#define PSI_FREQ (2*HZ+1) /* 2 sec intervals */
+#define EXP_10s 1677 /* 1/exp(2s/10s) as fixed-point */
+#define EXP_60s 1981 /* 1/exp(2s/60s) */
+#define EXP_300s 2034 /* 1/exp(2s/300s) */
+
+/* Sampling frequency in nanoseconds */
+static u64 psi_period __read_mostly;
+
+/* System-level pressure and stall tracking */
+static DEFINE_PER_CPU(struct psi_group_cpu, system_group_pcpu);
+static struct psi_group psi_system = {
+ .pcpu = &system_group_pcpu,
+};
+
+static void psi_update_work(struct work_struct *work);
+
+static void group_init(struct psi_group *group)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ seqcount_init(&per_cpu_ptr(group->pcpu, cpu)->seq);
+ group->next_update = sched_clock() + psi_period;
+ INIT_DELAYED_WORK(&group->clock_work, psi_update_work);
+ mutex_init(&group->stat_lock);
+}
+
+void __init psi_init(void)
+{
+ if (psi_disabled)
+ return;
+
+ psi_period = jiffies_to_nsecs(PSI_FREQ);
+ group_init(&psi_system);
+}
+
+static bool test_state(unsigned int *tasks, enum psi_states state)
+{
+ switch (state) {
+ case PSI_IO_SOME:
+ return tasks[NR_IOWAIT];
+ case PSI_IO_FULL:
+ return tasks[NR_IOWAIT] && !tasks[NR_RUNNING];
+ case PSI_MEM_SOME:
+ return tasks[NR_MEMSTALL];
+ case PSI_MEM_FULL:
+ return tasks[NR_MEMSTALL] && !tasks[NR_RUNNING];
+ case PSI_CPU_SOME:
+ return tasks[NR_RUNNING] > 1;
+ case PSI_NONIDLE:
+ return tasks[NR_IOWAIT] || tasks[NR_MEMSTALL] ||
+ tasks[NR_RUNNING];
+ default:
+ return false;
+ }
+}
+
+static void get_recent_times(struct psi_group *group, int cpu, u32 *times)
+{
+ struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu);
+ unsigned int tasks[NR_PSI_TASK_COUNTS];
+ u64 now, state_start;
+ unsigned int seq;
+ int s;
+
+ /* Snapshot a coherent view of the CPU state */
+ do {
+ seq = read_seqcount_begin(&groupc->seq);
+ now = cpu_clock(cpu);
+ memcpy(times, groupc->times, sizeof(groupc->times));
+ memcpy(tasks, groupc->tasks, sizeof(groupc->tasks));
+ state_start = groupc->state_start;
+ } while (read_seqcount_retry(&groupc->seq, seq));
+
+ /* Calculate state time deltas against the previous snapshot */
+ for (s = 0; s < NR_PSI_STATES; s++) {
+ u32 delta;
+ /*
+ * In addition to already concluded states, we also
+ * incorporate currently active states on the CPU,
+ * since states may last for many sampling periods.
+ *
+ * This way we keep our delta sampling buckets small
+ * (u32) and our reported pressure close to what's
+ * actually happening.
+ */
+ if (test_state(tasks, s))
+ times[s] += now - state_start;
+
+ delta = times[s] - groupc->times_prev[s];
+ groupc->times_prev[s] = times[s];
+
+ times[s] = delta;
+ }
+}
+
+static void calc_avgs(unsigned long avg[3], int missed_periods,
+ u64 time, u64 period)
+{
+ unsigned long pct;
+
+ /* Fill in zeroes for periods of no activity */
+ if (missed_periods) {
+ avg[0] = calc_load_n(avg[0], EXP_10s, 0, missed_periods);
+ avg[1] = calc_load_n(avg[1], EXP_60s, 0, missed_periods);
+ avg[2] = calc_load_n(avg[2], EXP_300s, 0, missed_periods);
+ }
+
+ /* Sample the most recent active period */
+ pct = div_u64(time * 100, period);
+ pct *= FIXED_1;
+ avg[0] = calc_load(avg[0], EXP_10s, pct);
+ avg[1] = calc_load(avg[1], EXP_60s, pct);
+ avg[2] = calc_load(avg[2], EXP_300s, pct);
+}
+
+static bool update_stats(struct psi_group *group)
+{
+ u64 deltas[NR_PSI_STATES - 1] = { 0, };
+ unsigned long missed_periods = 0;
+ unsigned long nonidle_total = 0;
+ u64 now, expires, period;
+ int cpu;
+ int s;
+
+ mutex_lock(&group->stat_lock);
+
+ /*
+ * Collect the per-cpu time buckets and average them into a
+ * single time sample that is normalized to wallclock time.
+ *
+ * For averaging, each CPU is weighted by its non-idle time in
+ * the sampling period. This eliminates artifacts from uneven
+ * loading, or even entirely idle CPUs.
+ */
+ for_each_possible_cpu(cpu) {
+ u32 times[NR_PSI_STATES];
+ u32 nonidle;
+
+ get_recent_times(group, cpu, times);
+
+ nonidle = nsecs_to_jiffies(times[PSI_NONIDLE]);
+ nonidle_total += nonidle;
+
+ for (s = 0; s < PSI_NONIDLE; s++)
+ deltas[s] += (u64)times[s] * nonidle;
+ }
+
+ /*
+ * Integrate the sample into the running statistics that are
+ * reported to userspace: the cumulative stall times and the
+ * decaying averages.
+ *
+ * Pressure percentages are sampled at PSI_FREQ. We might be
+ * called more often when the user polls more frequently than
+ * that; we might be called less often when there is no task
+ * activity, thus no data, and clock ticks are sporadic. The
+ * below handles both.
+ */
+
+ /* total= */
+ for (s = 0; s < NR_PSI_STATES - 1; s++)
+ group->total[s] += div_u64(deltas[s], max(nonidle_total, 1UL));
+
+ /* avgX= */
+ now = sched_clock();
+ expires = group->next_update;
+ if (now < expires)
+ goto out;
+ if (now - expires > psi_period)
+ missed_periods = div_u64(now - expires, psi_period);
+
+ /*
+ * The periodic clock tick can get delayed for various
+ * reasons, especially on loaded systems. To avoid clock
+ * drift, we schedule the clock in fixed psi_period intervals.
+ * But the deltas we sample out of the per-cpu buckets above
+ * are based on the actual time elapsing between clock ticks.
+ */
+ group->next_update = expires + ((1 + missed_periods) * psi_period);
+ period = now - (group->last_update + (missed_periods * psi_period));
+ group->last_update = now;
+
+ for (s = 0; s < NR_PSI_STATES - 1; s++) {
+ u32 sample;
+
+ sample = group->total[s] - group->total_prev[s];
+ /*
+ * Due to the lockless sampling of the time buckets,
+ * recorded time deltas can slip into the next period,
+ * which under full pressure can result in samples in
+ * excess of the period length.
+ *
+ * We don't want to report non-sensical pressures in
+ * excess of 100%, nor do we want to drop such events
+ * on the floor. Instead we punt any overage into the
+ * future until pressure subsides. By doing this we
+ * don't underreport the occurring pressure curve, we
+ * just report it delayed by one period length.
+ *
+ * The error isn't cumulative. As soon as another
+ * delta slips from a period P to P+1, by definition
+ * it frees up its time T in P.
+ */
+ if (sample > period)
+ sample = period;
+ group->total_prev[s] += sample;
+ calc_avgs(group->avg[s], missed_periods, sample, period);
+ }
+out:
+ mutex_unlock(&group->stat_lock);
+ return nonidle_total;
+}
+
+static void psi_update_work(struct work_struct *work)
+{
+ struct delayed_work *dwork;
+ struct psi_group *group;
+ bool nonidle;
+
+ dwork = to_delayed_work(work);
+ group = container_of(dwork, struct psi_group, clock_work);
+
+ /*
+ * If there is task activity, periodically fold the per-cpu
+ * times and feed samples into the running averages. If things
+ * are idle and there is no data to process, stop the clock.
+ * Once restarted, we'll catch up the running averages in one
+ * go - see calc_avgs() and missed_periods.
+ */
+
+ nonidle = update_stats(group);
+
+ if (nonidle) {
+ unsigned long delay = 0;
+ u64 now;
+
+ now = sched_clock();
+ if (group->next_update > now)
+ delay = nsecs_to_jiffies(group->next_update - now) + 1;
+ schedule_delayed_work(dwork, delay);
+ }
+}
+
+static void record_times(struct psi_group_cpu *groupc, int cpu,
+ bool memstall_tick)
+{
+ u32 delta;
+ u64 now;
+
+ now = cpu_clock(cpu);
+ delta = now - groupc->state_start;
+ groupc->state_start = now;
+
+ if (test_state(groupc->tasks, PSI_IO_SOME)) {
+ groupc->times[PSI_IO_SOME] += delta;
+ if (test_state(groupc->tasks, PSI_IO_FULL))
+ groupc->times[PSI_IO_FULL] += delta;
+ }
+
+ if (test_state(groupc->tasks, PSI_MEM_SOME)) {
+ groupc->times[PSI_MEM_SOME] += delta;
+ if (test_state(groupc->tasks, PSI_MEM_FULL))
+ groupc->times[PSI_MEM_FULL] += delta;
+ else if (memstall_tick) {
+ u32 sample;
+ /*
+ * Since we care about lost potential, a
+ * memstall is FULL when there are no other
+ * working tasks, but also when the CPU is
+ * actively reclaiming and nothing productive
+ * could run even if it were runnable.
+ *
+ * When the timer tick sees a reclaiming CPU,
+ * regardless of runnable tasks, sample a FULL
+ * tick (or less if it hasn't been a full tick
+ * since the last state change).
+ */
+ sample = min(delta, (u32)jiffies_to_nsecs(1));
+ groupc->times[PSI_MEM_FULL] += sample;
+ }
+ }
+
+ if (test_state(groupc->tasks, PSI_CPU_SOME))
+ groupc->times[PSI_CPU_SOME] += delta;
+
+ if (test_state(groupc->tasks, PSI_NONIDLE))
+ groupc->times[PSI_NONIDLE] += delta;
+}
+
+static void psi_group_change(struct psi_group *group, int cpu,
+ unsigned int clear, unsigned int set)
+{
+ struct psi_group_cpu *groupc;
+ unsigned int t, m;
+
+ groupc = per_cpu_ptr(group->pcpu, cpu);
+
+ /*
+ * First we assess the aggregate resource states this CPU's
+ * tasks have been in since the last change, and account any
+ * SOME and FULL time these may have resulted in.
+ *
+ * Then we update the task counts according to the state
+ * change requested through the @clear and @set bits.
+ */
+ write_seqcount_begin(&groupc->seq);
+
+ record_times(groupc, cpu, false);
+
+ for (t = 0, m = clear; m; m &= ~(1 << t), t++) {
+ if (!(m & (1 << t)))
+ continue;
+ if (groupc->tasks[t] == 0 && !psi_bug) {
+ printk_deferred(KERN_ERR "psi: task underflow! cpu=%d t=%d tasks=[%u %u %u] clear=%x set=%x\n",
+ cpu, t, groupc->tasks[0],
+ groupc->tasks[1], groupc->tasks[2],
+ clear, set);
+ psi_bug = 1;
+ }
+ groupc->tasks[t]--;
+ }
+
+ for (t = 0; set; set &= ~(1 << t), t++)
+ if (set & (1 << t))
+ groupc->tasks[t]++;
+
+ write_seqcount_end(&groupc->seq);
+
+ if (!delayed_work_pending(&group->clock_work))
+ schedule_delayed_work(&group->clock_work, PSI_FREQ);
+}
+
+void psi_task_change(struct task_struct *task, int clear, int set)
+{
+ int cpu = task_cpu(task);
+
+ if (!task->pid)
+ return;
+
+ if (((task->psi_flags & set) ||
+ (task->psi_flags & clear) != clear) &&
+ !psi_bug) {
+ printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n",
+ task->pid, task->comm, cpu,
+ task->psi_flags, clear, set);
+ psi_bug = 1;
+ }
+
+ task->psi_flags &= ~clear;
+ task->psi_flags |= set;
+
+ psi_group_change(&psi_system, cpu, clear, set);
+}
+
+void psi_memstall_tick(struct task_struct *task, int cpu)
+{
+ struct psi_group_cpu *groupc;
+
+ groupc = per_cpu_ptr(psi_system.pcpu, cpu);
+ write_seqcount_begin(&groupc->seq);
+ record_times(groupc, cpu, true);
+ write_seqcount_end(&groupc->seq);
+}
+
+/**
+ * psi_memstall_enter - mark the beginning of a memory stall section
+ * @flags: flags to handle nested sections
+ *
+ * Marks the calling task as being stalled due to a lack of memory,
+ * such as waiting for a refault or performing reclaim.
+ */
+void psi_memstall_enter(unsigned long *flags)
+{
+ struct rq_flags rf;
+ struct rq *rq;
+
+ if (psi_disabled)
+ return;
+
+ *flags = current->flags & PF_MEMSTALL;
+ if (*flags)
+ return;
+ /*
+ * PF_MEMSTALL setting & accounting needs to be atomic wrt
+ * changes to the task's scheduling state, otherwise we can
+ * race with CPU migration.
+ */
+ rq = this_rq_lock_irq(&rf);
+
+ current->flags |= PF_MEMSTALL;
+ psi_task_change(current, 0, TSK_MEMSTALL);
+
+ rq_unlock_irq(rq, &rf);
+}
+
+/**
+ * psi_memstall_leave - mark the end of an memory stall section
+ * @flags: flags to handle nested memdelay sections
+ *
+ * Marks the calling task as no longer stalled due to lack of memory.
+ */
+void psi_memstall_leave(unsigned long *flags)
+{
+ struct rq_flags rf;
+ struct rq *rq;
+
+ if (psi_disabled)
+ return;
+
+ if (*flags)
+ return;
+ /*
+ * PF_MEMSTALL clearing & accounting needs to be atomic wrt
+ * changes to the task's scheduling state, otherwise we could
+ * race with CPU migration.
+ */
+ rq = this_rq_lock_irq(&rf);
+
+ current->flags &= ~PF_MEMSTALL;
+ psi_task_change(current, TSK_MEMSTALL, 0);
+
+ rq_unlock_irq(rq, &rf);
+}
+
+static int psi_show(struct seq_file *m, struct psi_group *group,
+ enum psi_res res)
+{
+ int full;
+
+ if (psi_disabled)
+ return -EOPNOTSUPP;
+
+ update_stats(group);
+
+ for (full = 0; full < 2 - (res == PSI_CPU); full++) {
+ unsigned long avg[3];
+ u64 total;
+ int w;
+
+ for (w = 0; w < 3; w++)
+ avg[w] = group->avg[res * 2 + full][w];
+ total = div_u64(group->total[res * 2 + full], NSEC_PER_USEC);
+
+ seq_printf(m, "%s avg10=%lu.%02lu avg60=%lu.%02lu avg300=%lu.%02lu total=%llu\n",
+ full ? "full" : "some",
+ LOAD_INT(avg[0]), LOAD_FRAC(avg[0]),
+ LOAD_INT(avg[1]), LOAD_FRAC(avg[1]),
+ LOAD_INT(avg[2]), LOAD_FRAC(avg[2]),
+ total);
+ }
+
+ return 0;
+}
+
+static int psi_io_show(struct seq_file *m, void *v)
+{
+ return psi_show(m, &psi_system, PSI_IO);
+}
+
+static int psi_memory_show(struct seq_file *m, void *v)
+{
+ return psi_show(m, &psi_system, PSI_MEM);
+}
+
+static int psi_cpu_show(struct seq_file *m, void *v)
+{
+ return psi_show(m, &psi_system, PSI_CPU);
+}
+
+static int psi_io_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, psi_io_show, NULL);
+}
+
+static int psi_memory_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, psi_memory_show, NULL);
+}
+
+static int psi_cpu_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, psi_cpu_show, NULL);
+}
+
+static const struct file_operations psi_io_fops = {
+ .open = psi_io_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static const struct file_operations psi_memory_fops = {
+ .open = psi_memory_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static const struct file_operations psi_cpu_fops = {
+ .open = psi_cpu_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init psi_proc_init(void)
+{
+ proc_mkdir("pressure", NULL);
+ proc_create("pressure/io", 0, NULL, &psi_io_fops);
+ proc_create("pressure/memory", 0, NULL, &psi_memory_fops);
+ proc_create("pressure/cpu", 0, NULL, &psi_cpu_fops);
+ return 0;
+}
+module_init(psi_proc_init);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index e73d5d68602d..8139982a18a6 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -268,6 +268,7 @@ extern bool dl_cpu_busy(unsigned int cpu);
#ifdef CONFIG_CGROUP_SCHED
#include <linux/cgroup.h>
+#include <linux/psi.h>
struct cfs_rq;
struct rt_rq;
@@ -1717,6 +1718,8 @@ static inline void rq_last_tick_reset(struct rq *rq)
#endif
}
+extern void update_rq_clock(struct rq *rq);
+
extern void activate_task(struct rq *rq, struct task_struct *p, int flags);
extern void deactivate_task(struct rq *rq, struct task_struct *p, int flags);
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index baf500d12b7c..8ee534f7ac42 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -55,6 +55,92 @@ rq_sched_info_depart(struct rq *rq, unsigned long long delta)
#define schedstat_val_or_zero(var) 0
#endif /* CONFIG_SCHEDSTATS */
+#ifdef CONFIG_PSI
+/*
+ * PSI tracks state that persists across sleeps, such as iowaits and
+ * memory stalls. As a result, it has to distinguish between sleeps,
+ * where a task's runnable state changes, and requeues, where a task
+ * and its state are being moved between CPUs and runqueues.
+ */
+static inline void psi_enqueue(struct task_struct *p, bool wakeup)
+{
+ int clear = 0, set = TSK_RUNNING;
+
+ if (psi_disabled)
+ return;
+
+ if (!wakeup || p->sched_psi_wake_requeue) {
+ if (p->flags & PF_MEMSTALL)
+ set |= TSK_MEMSTALL;
+ if (p->sched_psi_wake_requeue)
+ p->sched_psi_wake_requeue = 0;
+ } else {
+ if (p->in_iowait)
+ clear |= TSK_IOWAIT;
+ }
+
+ psi_task_change(p, clear, set);
+}
+
+static inline void psi_dequeue(struct task_struct *p, bool sleep)
+{
+ int clear = TSK_RUNNING, set = 0;
+
+ if (psi_disabled)
+ return;
+
+ if (!sleep) {
+ if (p->flags & PF_MEMSTALL)
+ clear |= TSK_MEMSTALL;
+ } else {
+ if (p->in_iowait)
+ set |= TSK_IOWAIT;
+ }
+
+ psi_task_change(p, clear, set);
+}
+
+static inline void psi_ttwu_dequeue(struct task_struct *p)
+{
+ if (psi_disabled)
+ return;
+ /*
+ * Is the task being migrated during a wakeup? Make sure to
+ * deregister its sleep-persistent psi states from the old
+ * queue, and let psi_enqueue() know it has to requeue.
+ */
+ if (unlikely(p->in_iowait || (p->flags & PF_MEMSTALL))) {
+ struct rq_flags rf;
+ struct rq *rq;
+ int clear = 0;
+
+ if (p->in_iowait)
+ clear |= TSK_IOWAIT;
+ if (p->flags & PF_MEMSTALL)
+ clear |= TSK_MEMSTALL;
+
+ rq = __task_rq_lock(p, &rf);
+ psi_task_change(p, clear, 0);
+ p->sched_psi_wake_requeue = 1;
+ __task_rq_unlock(rq, &rf);
+ }
+}
+
+static inline void psi_task_tick(struct rq *rq)
+{
+ if (psi_disabled)
+ return;
+
+ if (unlikely(rq->curr->flags & PF_MEMSTALL))
+ psi_memstall_tick(rq->curr, cpu_of(rq));
+}
+#else /* CONFIG_PSI */
+static inline void psi_enqueue(struct task_struct *p, bool wakeup) {}
+static inline void psi_dequeue(struct task_struct *p, bool sleep) {}
+static inline void psi_ttwu_dequeue(struct task_struct *p) {}
+static inline void psi_task_tick(struct rq *rq) {}
+#endif /* CONFIG_PSI */
+
#ifdef CONFIG_SCHED_INFO
static inline void sched_info_reset_dequeued(struct task_struct *t)
{
diff --git a/mm/compaction.c b/mm/compaction.c
index 85395dc6eb13..c9827c820a92 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -22,6 +22,7 @@
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/page_owner.h>
+#include <linux/psi.h>
#include "internal.h"
#ifdef CONFIG_COMPACTION
@@ -2038,11 +2039,15 @@ static int kcompactd(void *p)
pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
while (!kthread_should_stop()) {
+ unsigned long pflags;
+
trace_mm_compaction_kcompactd_sleep(pgdat->node_id);
wait_event_freezable(pgdat->kcompactd_wait,
kcompactd_work_requested(pgdat));
+ psi_memstall_enter(&pflags);
kcompactd_do_work(pgdat);
+ psi_memstall_leave(&pflags);
}
return 0;
diff --git a/mm/filemap.c b/mm/filemap.c
index 51ed20eb2f2b..739750167f13 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -37,6 +37,7 @@
#include <linux/cleancache.h>
#include <linux/rmap.h>
#include <linux/delayacct.h>
+#include <linux/psi.h>
#include "internal.h"
#define CREATE_TRACE_POINTS
@@ -977,11 +978,14 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
struct wait_page_queue wait_page;
wait_queue_entry_t *wait = &wait_page.wait;
bool thrashing = false;
+ unsigned long pflags;
int ret = 0;
- if (bit_nr == PG_locked && !PageSwapBacked(page) &&
+ if (bit_nr == PG_locked &&
!PageUptodate(page) && PageWorkingset(page)) {
- delayacct_thrashing_start();
+ if (!PageSwapBacked(page))
+ delayacct_thrashing_start();
+ psi_memstall_enter(&pflags);
thrashing = true;
}
@@ -1023,8 +1027,11 @@ static inline int wait_on_page_bit_common(wait_queue_head_t *q,
finish_wait(q, wait);
- if (thrashing)
- delayacct_thrashing_end();
+ if (thrashing) {
+ if (!PageSwapBacked(page))
+ delayacct_thrashing_end();
+ psi_memstall_leave(&pflags);
+ }
/*
* A signal could leave PageWaiters set. Clearing it here if
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a2f365f40433..69041ffd87bc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -67,6 +67,7 @@
#include <linux/ftrace.h>
#include <linux/lockdep.h>
#include <linux/nmi.h>
+#include <linux/psi.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
@@ -3371,15 +3372,20 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
enum compact_priority prio, enum compact_result *compact_result)
{
struct page *page;
+ unsigned long pflags;
unsigned int noreclaim_flag;
if (!order)
return NULL;
+ psi_memstall_enter(&pflags);
noreclaim_flag = memalloc_noreclaim_save();
+
*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
prio);
+
memalloc_noreclaim_restore(noreclaim_flag);
+ psi_memstall_leave(&pflags);
if (*compact_result <= COMPACT_INACTIVE)
return NULL;
@@ -3568,11 +3574,13 @@ __perform_reclaim(gfp_t gfp_mask, unsigned int order,
struct reclaim_state reclaim_state;
int progress;
unsigned int noreclaim_flag;
+ unsigned long pflags;
cond_resched();
/* We now go into synchronous reclaim */
cpuset_memory_pressure_bump();
+ psi_memstall_enter(&pflags);
noreclaim_flag = memalloc_noreclaim_save();
fs_reclaim_acquire(gfp_mask);
reclaim_state.reclaimed_slab = 0;
@@ -3584,6 +3592,7 @@ __perform_reclaim(gfp_t gfp_mask, unsigned int order,
current->reclaim_state = NULL;
fs_reclaim_release(gfp_mask);
memalloc_noreclaim_restore(noreclaim_flag);
+ psi_memstall_leave(&pflags);
cond_resched();
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 06a7d1605a5d..860fc0f12176 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -49,6 +49,7 @@
#include <linux/prefetch.h>
#include <linux/printk.h>
#include <linux/dax.h>
+#include <linux/psi.h>
#include <asm/tlbflush.h>
#include <asm/div64.h>
@@ -3134,6 +3135,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
{
struct zonelist *zonelist;
unsigned long nr_reclaimed;
+ unsigned long pflags;
int nid;
unsigned int noreclaim_flag;
struct scan_control sc = {
@@ -3162,9 +3164,13 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
sc.gfp_mask,
sc.reclaim_idx);
+ psi_memstall_enter(&pflags);
noreclaim_flag = memalloc_noreclaim_save();
+
nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
+
memalloc_noreclaim_restore(noreclaim_flag);
+ psi_memstall_leave(&pflags);
trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed);
@@ -3329,6 +3335,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
int i;
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
+ unsigned long pflags;
struct zone *zone;
struct scan_control sc = {
.gfp_mask = GFP_KERNEL,
@@ -3338,6 +3345,9 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
.may_unmap = 1,
.may_swap = 1,
};
+
+ psi_memstall_enter(&pflags);
+
count_vm_event(PAGEOUTRUN);
do {
@@ -3432,6 +3442,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
out:
snapshot_refaults(NULL, pgdat);
+ psi_memstall_leave(&pflags);
/*
* Return the order kswapd stopped reclaiming at as
* prepare_kswapd_sleep() takes it into account. If another caller
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 09/11] psi: cgroup support
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (7 preceding siblings ...)
2019-03-12 10:19 ` [stable-4.14 08/11] psi: pressure stall information for CPU, memory, and IO Jack Wang
@ 2019-03-12 10:20 ` Jack Wang
2019-03-12 10:20 ` [stable-4.14 10/11] kernel/sched/psi.c: simplify cgroup_move_task() Jack Wang
` (2 subsequent siblings)
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:20 UTC (permalink / raw)
To: gregkh, stable
Cc: Johannes Weiner, Christopher Lameter, Ingo Molnar,
Johannes Weiner, Mike Galbraith, Peter Enderborg, Randy Dunlap,
Shakeel Butt, Vinayak Menon, Andrew Morton, Linus Torvalds,
Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
On a system that executes multiple cgrouped jobs and independent
workloads, we don't just care about the health of the overall system, but
also that of individual jobs, so that we can ensure individual job health,
fairness between jobs, or prioritize some jobs over others.
This patch implements pressure stall tracking for cgroups. In kernels
with CONFIG_PSI=y, cgroup2 groups will have cpu.pressure, memory.pressure,
and io.pressure files that track aggregate pressure stall times for only
the tasks inside the cgroup.
Link: http://lkml.kernel.org/r/20180828172258.3185-10-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Drake <drake@endlessm.com>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 992fe97ea79dcb03297f72c36bd7cff990e02232)
[jwang: to do check error case]
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Conflicts:
Documentation/cgroup-v2.txt
kernel/cgroup/cgroup.c
---
Documentation/accounting/psi.txt | 9 +++
Documentation/cgroup-v2.txt | 17 +++++
include/linux/cgroup-defs.h | 4 ++
include/linux/cgroup.h | 15 ++++
include/linux/psi.h | 25 +++++++
init/Kconfig | 4 ++
kernel/cgroup/cgroup.c | 44 +++++++++++-
kernel/sched/psi.c | 118 ++++++++++++++++++++++++++++---
8 files changed, 227 insertions(+), 9 deletions(-)
diff --git a/Documentation/accounting/psi.txt b/Documentation/accounting/psi.txt
index 3753a82f1cf5..b8ca28b60215 100644
--- a/Documentation/accounting/psi.txt
+++ b/Documentation/accounting/psi.txt
@@ -62,3 +62,12 @@ well as medium and long term trends. The total absolute stall time is
tracked and exported as well, to allow detection of latency spikes
which wouldn't necessarily make a dent in the time averages, or to
average trends over custom time frames.
+
+Cgroup2 interface
+=================
+
+In a system with a CONFIG_CGROUP=y kernel and the cgroup2 filesystem
+mounted, pressure stall information is also tracked for tasks grouped
+into cgroups. Each subdirectory in the cgroupfs mountpoint contains
+cpu.pressure, memory.pressure, and io.pressure files; the format is
+the same as the /proc/pressure/ files.
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index dc44785dc0fa..5cd589694a6a 100644
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt
@@ -957,6 +957,11 @@ All time durations are in microseconds.
which indicates that the group may consume upto $MAX in each
$PERIOD duration. If only one number is written, $MAX is
updated.
+ cpu.pressure
+ A read-only nested-key file which exists on non-root cgroups.
+
+ Shows pressure stall information for CPU. See
+ Documentation/accounting/psi.txt for details.
Memory
@@ -1194,6 +1199,12 @@ PAGE_SIZE multiple when read back.
Swap usage hard limit. If a cgroup's swap usage reaches this
limit, anonymous meomry of the cgroup will not be swapped out.
+ memory.pressure
+ A read-only nested-key file which exists on non-root cgroups.
+
+ Shows pressure stall information for memory. See
+ Documentation/accounting/psi.txt for details.
+
Usage Guidelines
~~~~~~~~~~~~~~~~
@@ -1329,6 +1340,12 @@ IO Interface Files
8:16 rbps=2097152 wbps=max riops=max wiops=max
+ io.pressure
+ A read-only nested-key file which exists on non-root cgroups.
+
+ Shows pressure stall information for IO. See
+ Documentation/accounting/psi.txt for details.
+
Writeback
~~~~~~~~~
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index e7905d9353e8..f113ebd940e0 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -19,6 +19,7 @@
#include <linux/percpu-rwsem.h>
#include <linux/workqueue.h>
#include <linux/bpf-cgroup.h>
+#include <linux/psi_types.h>
#ifdef CONFIG_CGROUPS
@@ -368,6 +369,9 @@ struct cgroup {
/* used to schedule release agent */
struct work_struct release_agent_work;
+ /* used to track pressure stalls */
+ struct psi_group psi;
+
/* used to store eBPF programs */
struct cgroup_bpf bpf;
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index dddbc29e2009..28a1a067da52 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -626,6 +626,11 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
pr_cont_kernfs_path(cgrp->kn);
}
+static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
+{
+ return &cgrp->psi;
+}
+
static inline void cgroup_init_kthreadd(void)
{
/*
@@ -679,6 +684,16 @@ static inline union kernfs_node_id *cgroup_get_kernfs_id(struct cgroup *cgrp)
return NULL;
}
+static inline struct cgroup *cgroup_parent(struct cgroup *cgrp)
+{
+ return NULL;
+}
+
+static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
+{
+ return NULL;
+}
+
static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
struct cgroup *ancestor)
{
diff --git a/include/linux/psi.h b/include/linux/psi.h
index b0daf050de58..8e0725aac0aa 100644
--- a/include/linux/psi.h
+++ b/include/linux/psi.h
@@ -4,6 +4,9 @@
#include <linux/psi_types.h>
#include <linux/sched.h>
+struct seq_file;
+struct css_set;
+
#ifdef CONFIG_PSI
extern bool psi_disabled;
@@ -16,6 +19,14 @@ void psi_memstall_tick(struct task_struct *task, int cpu);
void psi_memstall_enter(unsigned long *flags);
void psi_memstall_leave(unsigned long *flags);
+int psi_show(struct seq_file *s, struct psi_group *group, enum psi_res res);
+
+#ifdef CONFIG_CGROUPS
+int psi_cgroup_alloc(struct cgroup *cgrp);
+void psi_cgroup_free(struct cgroup *cgrp);
+void cgroup_move_task(struct task_struct *p, struct css_set *to);
+#endif
+
#else /* CONFIG_PSI */
static inline void psi_init(void) {}
@@ -23,6 +34,20 @@ static inline void psi_init(void) {}
static inline void psi_memstall_enter(unsigned long *flags) {}
static inline void psi_memstall_leave(unsigned long *flags) {}
+#ifdef CONFIG_CGROUPS
+static inline int psi_cgroup_alloc(struct cgroup *cgrp)
+{
+ return 0;
+}
+static inline void psi_cgroup_free(struct cgroup *cgrp)
+{
+}
+static inline void cgroup_move_task(struct task_struct *p, struct css_set *to)
+{
+ rcu_assign_pointer(p->cgroups, to);
+}
+#endif
+
#endif /* CONFIG_PSI */
#endif /* _LINUX_PSI_H */
diff --git a/init/Kconfig b/init/Kconfig
index d19c853088c1..cb22efbd74d9 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -481,6 +481,10 @@ config PSI
the share of walltime in which some or all tasks in the system are
delayed due to contention of the respective resource.
+ In kernels with cgroup support, cgroups (cgroup2 only) will
+ have cpu.pressure, memory.pressure, and io.pressure files,
+ which aggregate pressure stalls for the grouped tasks only.
+
For more details see Documentation/accounting/psi.txt.
Say N if unsure.
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 21bbfc09e395..0897e980a2e2 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -54,6 +54,7 @@
#include <linux/proc_ns.h>
#include <linux/nsproxy.h>
#include <linux/file.h>
+#include <linux/psi.h>
#include <net/sock.h>
#define CREATE_TRACE_POINTS
@@ -794,7 +795,7 @@ static void css_set_move_task(struct task_struct *task,
*/
WARN_ON_ONCE(task->flags & PF_EXITING);
- rcu_assign_pointer(task->cgroups, to_cset);
+ cgroup_move_task(task, to_cset);
list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
&to_cset->tasks);
}
@@ -3329,6 +3330,21 @@ static int cgroup_stat_show(struct seq_file *seq, void *v)
return 0;
}
+#ifdef CONFIG_PSI
+static int cgroup_io_pressure_show(struct seq_file *seq, void *v)
+{
+ return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_IO);
+}
+static int cgroup_memory_pressure_show(struct seq_file *seq, void *v)
+{
+ return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_MEM);
+}
+static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v)
+{
+ return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_CPU);
+}
+#endif
+
static int cgroup_file_open(struct kernfs_open_file *of)
{
struct cftype *cft = of->kn->priv;
@@ -4439,6 +4455,23 @@ static struct cftype cgroup_base_files[] = {
.name = "cgroup.stat",
.seq_show = cgroup_stat_show,
},
+#ifdef CONFIG_PSI
+ {
+ .name = "io.pressure",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_io_pressure_show,
+ },
+ {
+ .name = "memory.pressure",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_memory_pressure_show,
+ },
+ {
+ .name = "cpu.pressure",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_cpu_pressure_show,
+ },
+#endif
{ } /* terminate */
};
@@ -4499,6 +4532,7 @@ static void css_free_work_fn(struct work_struct *work)
*/
cgroup_put(cgroup_parent(cgrp));
kernfs_put(cgrp->kn);
+ psi_cgroup_free(cgrp);
kfree(cgrp);
} else {
/*
@@ -4742,6 +4776,10 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
cgrp->root = root;
cgrp->level = level;
+ ret = psi_cgroup_alloc(cgrp);
+ if (ret)
+ goto out_idr_free;
+
for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
cgrp->ancestor_ids[tcgrp->level] = tcgrp->id;
@@ -4782,6 +4820,10 @@ static struct cgroup *cgroup_create(struct cgroup *parent)
return cgrp;
+out_psi_free:
+ psi_cgroup_free(cgrp);
+out_idr_free:
+ cgroup_idr_remove(&root->cgroup_idr, cgrp->id);
out_cancel_ref:
percpu_ref_exit(&cgrp->self.refcnt);
out_free_cgrp:
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 595414599b98..7cdecfc010af 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -473,9 +473,35 @@ static void psi_group_change(struct psi_group *group, int cpu,
schedule_delayed_work(&group->clock_work, PSI_FREQ);
}
+static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
+{
+#ifdef CONFIG_CGROUPS
+ struct cgroup *cgroup = NULL;
+
+ if (!*iter)
+ cgroup = task->cgroups->dfl_cgrp;
+ else if (*iter == &psi_system)
+ return NULL;
+ else
+ cgroup = cgroup_parent(*iter);
+
+ if (cgroup && cgroup_parent(cgroup)) {
+ *iter = cgroup;
+ return cgroup_psi(cgroup);
+ }
+#else
+ if (*iter)
+ return NULL;
+#endif
+ *iter = &psi_system;
+ return &psi_system;
+}
+
void psi_task_change(struct task_struct *task, int clear, int set)
{
int cpu = task_cpu(task);
+ struct psi_group *group;
+ void *iter = NULL;
if (!task->pid)
return;
@@ -492,17 +518,23 @@ void psi_task_change(struct task_struct *task, int clear, int set)
task->psi_flags &= ~clear;
task->psi_flags |= set;
- psi_group_change(&psi_system, cpu, clear, set);
+ while ((group = iterate_groups(task, &iter)))
+ psi_group_change(group, cpu, clear, set);
}
void psi_memstall_tick(struct task_struct *task, int cpu)
{
- struct psi_group_cpu *groupc;
+ struct psi_group *group;
+ void *iter = NULL;
- groupc = per_cpu_ptr(psi_system.pcpu, cpu);
- write_seqcount_begin(&groupc->seq);
- record_times(groupc, cpu, true);
- write_seqcount_end(&groupc->seq);
+ while ((group = iterate_groups(task, &iter))) {
+ struct psi_group_cpu *groupc;
+
+ groupc = per_cpu_ptr(group->pcpu, cpu);
+ write_seqcount_begin(&groupc->seq);
+ record_times(groupc, cpu, true);
+ write_seqcount_end(&groupc->seq);
+ }
}
/**
@@ -565,8 +597,78 @@ void psi_memstall_leave(unsigned long *flags)
rq_unlock_irq(rq, &rf);
}
-static int psi_show(struct seq_file *m, struct psi_group *group,
- enum psi_res res)
+#ifdef CONFIG_CGROUPS
+int psi_cgroup_alloc(struct cgroup *cgroup)
+{
+ if (psi_disabled)
+ return 0;
+
+ cgroup->psi.pcpu = alloc_percpu(struct psi_group_cpu);
+ if (!cgroup->psi.pcpu)
+ return -ENOMEM;
+ group_init(&cgroup->psi);
+ return 0;
+}
+
+void psi_cgroup_free(struct cgroup *cgroup)
+{
+ if (psi_disabled)
+ return;
+
+ cancel_delayed_work_sync(&cgroup->psi.clock_work);
+ free_percpu(cgroup->psi.pcpu);
+}
+
+/**
+ * cgroup_move_task - move task to a different cgroup
+ * @task: the task
+ * @to: the target css_set
+ *
+ * Move task to a new cgroup and safely migrate its associated stall
+ * state between the different groups.
+ *
+ * This function acquires the task's rq lock to lock out concurrent
+ * changes to the task's scheduling state and - in case the task is
+ * running - concurrent changes to its stall state.
+ */
+void cgroup_move_task(struct task_struct *task, struct css_set *to)
+{
+ bool move_psi = !psi_disabled;
+ unsigned int task_flags = 0;
+ struct rq_flags rf;
+ struct rq *rq;
+
+ if (move_psi) {
+ rq = task_rq_lock(task, &rf);
+
+ if (task_on_rq_queued(task))
+ task_flags = TSK_RUNNING;
+ else if (task->in_iowait)
+ task_flags = TSK_IOWAIT;
+
+ if (task->flags & PF_MEMSTALL)
+ task_flags |= TSK_MEMSTALL;
+
+ if (task_flags)
+ psi_task_change(task, task_flags, 0);
+ }
+
+ /*
+ * Lame to do this here, but the scheduler cannot be locked
+ * from the outside, so we move cgroups from inside sched/.
+ */
+ rcu_assign_pointer(task->cgroups, to);
+
+ if (move_psi) {
+ if (task_flags)
+ psi_task_change(task, 0, task_flags);
+
+ task_rq_unlock(rq, task, &rf);
+ }
+}
+#endif /* CONFIG_CGROUPS */
+
+int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
{
int full;
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 10/11] kernel/sched/psi.c: simplify cgroup_move_task()
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (8 preceding siblings ...)
2019-03-12 10:20 ` [stable-4.14 09/11] psi: cgroup support Jack Wang
@ 2019-03-12 10:20 ` Jack Wang
2019-03-12 10:20 ` [stable-4.14 11/11] psi: make disabling/enabling easier for vendor kernels Jack Wang
2019-03-12 11:43 ` [RFC stable-4.14 00/11] PSI feature for 4.14 Greg KH
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:20 UTC (permalink / raw)
To: gregkh, stable
Cc: Olof Johansson, Ingo Molnar, Peter Zijlstra, Andrew Morton,
Linus Torvalds, Jack Wang
From: Olof Johansson <olof@lixom.net>
The existing code triggered an invalid warning about 'rq' possibly being
used uninitialized. Instead of doing the silly warning suppression by
initializa it to NULL, refactor the code to bail out early instead.
Warning was:
kernel/sched/psi.c: In function `cgroup_move_task':
kernel/sched/psi.c:639:13: warning: `rq' may be used uninitialized in this function [-Wmaybe-uninitialized]
Link: http://lkml.kernel.org/r/20181103183339.8669-1-olof@lixom.net
Fixes: 2ce7135adc9ad ("psi: cgroup support")
Signed-off-by: Olof Johansson <olof@lixom.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit c904648b96279bd44e1f08f474274cd1ee52675d)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
kernel/sched/psi.c | 43 ++++++++++++++++++++++---------------------
1 file changed, 22 insertions(+), 21 deletions(-)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 7cdecfc010af..3d7355d7c3e3 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -633,38 +633,39 @@ void psi_cgroup_free(struct cgroup *cgroup)
*/
void cgroup_move_task(struct task_struct *task, struct css_set *to)
{
- bool move_psi = !psi_disabled;
unsigned int task_flags = 0;
struct rq_flags rf;
struct rq *rq;
- if (move_psi) {
- rq = task_rq_lock(task, &rf);
+ if (psi_disabled) {
+ /*
+ * Lame to do this here, but the scheduler cannot be locked
+ * from the outside, so we move cgroups from inside sched/.
+ */
+ rcu_assign_pointer(task->cgroups, to);
+ return;
+ }
- if (task_on_rq_queued(task))
- task_flags = TSK_RUNNING;
- else if (task->in_iowait)
- task_flags = TSK_IOWAIT;
+ rq = task_rq_lock(task, &rf);
- if (task->flags & PF_MEMSTALL)
- task_flags |= TSK_MEMSTALL;
+ if (task_on_rq_queued(task))
+ task_flags = TSK_RUNNING;
+ else if (task->in_iowait)
+ task_flags = TSK_IOWAIT;
- if (task_flags)
- psi_task_change(task, task_flags, 0);
- }
+ if (task->flags & PF_MEMSTALL)
+ task_flags |= TSK_MEMSTALL;
- /*
- * Lame to do this here, but the scheduler cannot be locked
- * from the outside, so we move cgroups from inside sched/.
- */
+ if (task_flags)
+ psi_task_change(task, task_flags, 0);
+
+ /* See comment above */
rcu_assign_pointer(task->cgroups, to);
- if (move_psi) {
- if (task_flags)
- psi_task_change(task, 0, task_flags);
+ if (task_flags)
+ psi_task_change(task, 0, task_flags);
- task_rq_unlock(rq, task, &rf);
- }
+ task_rq_unlock(rq, task, &rf);
}
#endif /* CONFIG_CGROUPS */
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* [stable-4.14 11/11] psi: make disabling/enabling easier for vendor kernels
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (9 preceding siblings ...)
2019-03-12 10:20 ` [stable-4.14 10/11] kernel/sched/psi.c: simplify cgroup_move_task() Jack Wang
@ 2019-03-12 10:20 ` Jack Wang
2019-03-12 11:43 ` [RFC stable-4.14 00/11] PSI feature for 4.14 Greg KH
11 siblings, 0 replies; 18+ messages in thread
From: Jack Wang @ 2019-03-12 10:20 UTC (permalink / raw)
To: gregkh, stable; +Cc: Johannes Weiner, Andrew Morton, Linus Torvalds, Jack Wang
From: Johannes Weiner <hannes@cmpxchg.org>
Mel Gorman reports a hackbench regression with psi that would prohibit
shipping the suse kernel with it default-enabled, but he'd still like
users to be able to opt in at little to no cost to others.
With the current combination of CONFIG_PSI and the psi_disabled bool set
from the commandline, this is a challenge. Do the following things to
make it easier:
1. Add a config option CONFIG_PSI_DEFAULT_DISABLED that allows distros
to enable CONFIG_PSI in their kernel but leave the feature disabled
unless a user requests it at boot-time.
To avoid double negatives, rename psi_disabled= to psi=.
2. Make psi_disabled a static branch to eliminate any branch costs
when the feature is disabled.
In terms of numbers before and after this patch, Mel says:
: The following is a comparision using CONFIG_PSI=n as a baseline against
: your patch and a vanilla kernel
:
: 4.20.0-rc4 4.20.0-rc4 4.20.0-rc4
: kconfigdisable-v1r1 vanilla psidisable-v1r1
: Amean 1 1.3100 ( 0.00%) 1.3923 ( -6.28%) 1.3427 ( -2.49%)
: Amean 3 3.8860 ( 0.00%) 4.1230 * -6.10%* 3.8860 ( -0.00%)
: Amean 5 6.8847 ( 0.00%) 8.0390 * -16.77%* 6.7727 ( 1.63%)
: Amean 7 9.9310 ( 0.00%) 10.8367 * -9.12%* 9.9910 ( -0.60%)
: Amean 12 16.6577 ( 0.00%) 18.2363 * -9.48%* 17.1083 ( -2.71%)
: Amean 18 26.5133 ( 0.00%) 27.8833 * -5.17%* 25.7663 ( 2.82%)
: Amean 24 34.3003 ( 0.00%) 34.6830 ( -1.12%) 32.0450 ( 6.58%)
: Amean 30 40.0063 ( 0.00%) 40.5800 ( -1.43%) 41.5087 ( -3.76%)
: Amean 32 40.1407 ( 0.00%) 41.2273 ( -2.71%) 39.9417 ( 0.50%)
:
: It's showing that the vanilla kernel takes a hit (as the bisection
: indicated it would) and that disabling PSI by default is reasonably
: close in terms of performance for this particular workload on this
: particular machine so;
Link: http://lkml.kernel.org/r/20181127165329.GA29728@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit e0c274472d5d27f277af722e017525e0b33784cd)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
.../admin-guide/kernel-parameters.txt | 4 +++
include/linux/psi.h | 3 +-
init/Kconfig | 9 ++++++
kernel/sched/psi.c | 30 +++++++++++++------
kernel/sched/stats.h | 8 ++---
5 files changed, 40 insertions(+), 14 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 7d8b17ce8804..f6a77b9a9d26 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3322,6 +3322,10 @@
before loading.
See Documentation/blockdev/ramdisk.txt.
+ psi= [KNL] Enable or disable pressure stall information
+ tracking.
+ Format: <bool>
+
psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
probe for; one of (bare|imps|exps|lifebook|any).
psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
diff --git a/include/linux/psi.h b/include/linux/psi.h
index 8e0725aac0aa..7006008d5b72 100644
--- a/include/linux/psi.h
+++ b/include/linux/psi.h
@@ -1,6 +1,7 @@
#ifndef _LINUX_PSI_H
#define _LINUX_PSI_H
+#include <linux/jump_label.h>
#include <linux/psi_types.h>
#include <linux/sched.h>
@@ -9,7 +10,7 @@ struct css_set;
#ifdef CONFIG_PSI
-extern bool psi_disabled;
+extern struct static_key_false psi_disabled;
void psi_init(void);
diff --git a/init/Kconfig b/init/Kconfig
index cb22efbd74d9..e3cdc827af4e 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -489,6 +489,15 @@ config PSI
Say N if unsure.
+config PSI_DEFAULT_DISABLED
+ bool "Require boot parameter to enable pressure stall information tracking"
+ default n
+ depends on PSI
+ help
+ If set, pressure stall information tracking will be disabled
+ per default but can be enabled through passing psi_enable=1
+ on the kernel commandline during boot.
+
endmenu # "CPU/Task time and stats accounting"
source "kernel/rcu/Kconfig"
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 3d7355d7c3e3..fe24de3fbc93 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -136,8 +136,18 @@
static int psi_bug __read_mostly;
-bool psi_disabled __read_mostly;
-core_param(psi_disabled, psi_disabled, bool, 0644);
+DEFINE_STATIC_KEY_FALSE(psi_disabled);
+
+#ifdef CONFIG_PSI_DEFAULT_DISABLED
+bool psi_enable;
+#else
+bool psi_enable = true;
+#endif
+static int __init setup_psi(char *str)
+{
+ return kstrtobool(str, &psi_enable) == 0;
+}
+__setup("psi=", setup_psi);
/* Running averages - we need to be higher-res than loadavg */
#define PSI_FREQ (2*HZ+1) /* 2 sec intervals */
@@ -169,8 +179,10 @@ static void group_init(struct psi_group *group)
void __init psi_init(void)
{
- if (psi_disabled)
+ if (!psi_enable) {
+ static_branch_enable(&psi_disabled);
return;
+ }
psi_period = jiffies_to_nsecs(PSI_FREQ);
group_init(&psi_system);
@@ -549,7 +561,7 @@ void psi_memstall_enter(unsigned long *flags)
struct rq_flags rf;
struct rq *rq;
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return;
*flags = current->flags & PF_MEMSTALL;
@@ -579,7 +591,7 @@ void psi_memstall_leave(unsigned long *flags)
struct rq_flags rf;
struct rq *rq;
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return;
if (*flags)
@@ -600,7 +612,7 @@ void psi_memstall_leave(unsigned long *flags)
#ifdef CONFIG_CGROUPS
int psi_cgroup_alloc(struct cgroup *cgroup)
{
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return 0;
cgroup->psi.pcpu = alloc_percpu(struct psi_group_cpu);
@@ -612,7 +624,7 @@ int psi_cgroup_alloc(struct cgroup *cgroup)
void psi_cgroup_free(struct cgroup *cgroup)
{
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return;
cancel_delayed_work_sync(&cgroup->psi.clock_work);
@@ -637,7 +649,7 @@ void cgroup_move_task(struct task_struct *task, struct css_set *to)
struct rq_flags rf;
struct rq *rq;
- if (psi_disabled) {
+ if (static_branch_likely(&psi_disabled)) {
/*
* Lame to do this here, but the scheduler cannot be locked
* from the outside, so we move cgroups from inside sched/.
@@ -673,7 +685,7 @@ int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
{
int full;
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return -EOPNOTSUPP;
update_stats(group);
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 8ee534f7ac42..5d30f4b7d344 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -66,7 +66,7 @@ static inline void psi_enqueue(struct task_struct *p, bool wakeup)
{
int clear = 0, set = TSK_RUNNING;
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return;
if (!wakeup || p->sched_psi_wake_requeue) {
@@ -86,7 +86,7 @@ static inline void psi_dequeue(struct task_struct *p, bool sleep)
{
int clear = TSK_RUNNING, set = 0;
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return;
if (!sleep) {
@@ -102,7 +102,7 @@ static inline void psi_dequeue(struct task_struct *p, bool sleep)
static inline void psi_ttwu_dequeue(struct task_struct *p)
{
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return;
/*
* Is the task being migrated during a wakeup? Make sure to
@@ -128,7 +128,7 @@ static inline void psi_ttwu_dequeue(struct task_struct *p)
static inline void psi_task_tick(struct rq *rq)
{
- if (psi_disabled)
+ if (static_branch_likely(&psi_disabled))
return;
if (unlikely(rq->curr->flags & PF_MEMSTALL))
--
2.17.1
^ permalink raw reply related [flat|nested] 18+ messages in thread* Re: [RFC stable-4.14 00/11] PSI feature for 4.14
2019-03-12 10:19 [RFC stable-4.14 00/11] PSI feature for 4.14 Jack Wang
` (10 preceding siblings ...)
2019-03-12 10:20 ` [stable-4.14 11/11] psi: make disabling/enabling easier for vendor kernels Jack Wang
@ 2019-03-12 11:43 ` Greg KH
2019-03-13 10:15 ` Jinpu Wang
11 siblings, 1 reply; 18+ messages in thread
From: Greg KH @ 2019-03-12 11:43 UTC (permalink / raw)
To: Jack Wang; +Cc: stable
On Tue, Mar 12, 2019 at 11:19:51AM +0100, Jack Wang wrote:
> Hi Folks,
>
> This is a backport for PSI feature from:
> http://git.cmpxchg.org/cgit.cgi/linux-psi.git/log/?h=psi-4.17
>
> The patches are included since 4.20.
>
> We're run LTP tests and stress test with these patches on 4.14.93,
> no problem found.
>
> I send them out for review, also maybe there are other guys are intereseted.
>
> I kept the conflict note in commit message, so it's easier to review.
This is nice, but why? We can't take new features into the stable
kernel trees. For Android devices (which do want PSI), all of the
patches are already backported into the android-common 4.14 branch,
right? Or does this differ from that backport somehow?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 18+ messages in thread* Re: [RFC stable-4.14 00/11] PSI feature for 4.14
2019-03-12 11:43 ` [RFC stable-4.14 00/11] PSI feature for 4.14 Greg KH
@ 2019-03-13 10:15 ` Jinpu Wang
2019-03-14 17:29 ` Greg KH
0 siblings, 1 reply; 18+ messages in thread
From: Jinpu Wang @ 2019-03-13 10:15 UTC (permalink / raw)
To: Greg KH; +Cc: v3.14+, only the raid10 part
snip
> This is nice, but why? We can't take new features into the stable
> kernel trees. For Android devices (which do want PSI), all of the
> patches are already backported into the android-common 4.14 branch,
> right? Or does this differ from that backport somehow?
>
> thanks,
>
> greg k-h
(Resend to reply to all, sorry)
Thanks Greg,
We want the feature for our product. Yeah, I know we have
stable-rules, didn't expect
the patches to be included, just in case other guys also need PSI.
I'm not aware of android-common did the backport already, could you
point me the link?
I checked in
https://android.googlesource.com/kernel/common/+/refs/heads/android-4.14*
I didn't find the psi support.
Regards,
Jack
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [RFC stable-4.14 00/11] PSI feature for 4.14
2019-03-13 10:15 ` Jinpu Wang
@ 2019-03-14 17:29 ` Greg KH
2019-03-15 10:48 ` Jinpu Wang
0 siblings, 1 reply; 18+ messages in thread
From: Greg KH @ 2019-03-14 17:29 UTC (permalink / raw)
To: Jinpu Wang; +Cc: v3.14+, only the raid10 part
On Wed, Mar 13, 2019 at 11:15:43AM +0100, Jinpu Wang wrote:
> snip
> > This is nice, but why? We can't take new features into the stable
> > kernel trees. For Android devices (which do want PSI), all of the
> > patches are already backported into the android-common 4.14 branch,
> > right? Or does this differ from that backport somehow?
> >
> > thanks,
> >
> > greg k-h
> (Resend to reply to all, sorry)
>
> Thanks Greg,
>
> We want the feature for our product. Yeah, I know we have
> stable-rules, didn't expect
> the patches to be included, just in case other guys also need PSI.
>
> I'm not aware of android-common did the backport already, could you
> point me the link?
>
> I checked in
> https://android.googlesource.com/kernel/common/+/refs/heads/android-4.14*
>
> I didn't find the psi support.
Ah, I was wrong, sorry, it has been submitted to AOSP, but not merged
yet. Here's the 4.14 patches queued up and ready to go:
https://android-review.googlesource.com/q/topic:%22psi+4.14+backport%22+(status:open%20OR%20status:merged)
The 4.9 and 4.19 branches also have them queued up:
https://android-review.googlesource.com/q/topic:%22psi+4.9+backport%22+(status:open%20OR%20status:merged)
https://android-review.googlesource.com/q/topic:%22psi+4.19+backport%22+(status:open%20OR%20status:merged)
I talked to the developer this week and he said he was waiting for a few
of the remaining patches to be merged upstream first before merging to
AOSP to ensure that nothing diverged. Hopefully that should happen in a
few weeks or so, after the merge window is open and maintainers reopen
their development branches.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [RFC stable-4.14 00/11] PSI feature for 4.14
2019-03-14 17:29 ` Greg KH
@ 2019-03-15 10:48 ` Jinpu Wang
0 siblings, 0 replies; 18+ messages in thread
From: Jinpu Wang @ 2019-03-15 10:48 UTC (permalink / raw)
To: Greg KH; +Cc: v3.14+, only the raid10 part
Greg KH <gregkh@linuxfoundation.org> 于2019年3月14日周四 下午6:29写道：
>
> On Wed, Mar 13, 2019 at 11:15:43AM +0100, Jinpu Wang wrote:
> > snip
> > > This is nice, but why? We can't take new features into the stable
> > > kernel trees. For Android devices (which do want PSI), all of the
> > > patches are already backported into the android-common 4.14 branch,
> > > right? Or does this differ from that backport somehow?
> > >
> > > thanks,
> > >
> > > greg k-h
> > (Resend to reply to all, sorry)
> >
> > Thanks Greg,
> >
> > We want the feature for our product. Yeah, I know we have
> > stable-rules, didn't expect
> > the patches to be included, just in case other guys also need PSI.
> >
> > I'm not aware of android-common did the backport already, could you
> > point me the link?
> >
> > I checked in
> > https://android.googlesource.com/kernel/common/+/refs/heads/android-4.14*
> >
> > I didn't find the psi support.
>
> Ah, I was wrong, sorry, it has been submitted to AOSP, but not merged
> yet. Here's the 4.14 patches queued up and ready to go:
> https://android-review.googlesource.com/q/topic:%22psi+4.14+backport%22+(status:open%20OR%20status:merged)
>
> The 4.9 and 4.19 branches also have them queued up:
> https://android-review.googlesource.com/q/topic:%22psi+4.9+backport%22+(status:open%20OR%20status:merged)
> https://android-review.googlesource.com/q/topic:%22psi+4.19+backport%22+(status:open%20OR%20status:merged)
>
> I talked to the developer this week and he said he was waiting for a few
> of the remaining patches to be merged upstream first before merging to
> AOSP to ensure that nothing diverged. Hopefully that should happen in a
> few weeks or so, after the merge window is open and maintainers reopen
> their development branches.
>
> thanks,
>
> greg k-h
Thanks Greg,
It's very helpful, I indeed missed some patches.
I will check their backport.
Regards,
Jack
^ permalink raw reply [flat|nested] 18+ messages in thread