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| author |   Peter Zijlstra <peterz@infradead.org> | 2017-03-01 11:24:35 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2017-03-02 08:50:17 +0100 |
| commit | 4c77b18cf8b7ab37c7d5737b4609010d2ceec5f0 (patch) | |
| tree | 9810db6cc4cfc6ab80aa0704d9bef7d9634497fb /kernel/sched | |
| parent | Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff) | |
| download | linux-dev-4c77b18cf8b7ab37c7d5737b4609010d2ceec5f0.tar.xz linux-dev-4c77b18cf8b7ab37c7d5737b4609010d2ceec5f0.zip | |
sched/fair: Make select_idle_cpu() more aggressive
Kitsunyan reported desktop latency issues on his Celeron 887 because
of commit:
1b568f0aabf2 ("sched/core: Optimize SCHED_SMT")
... even though his CPU doesn't do SMT.
The effect of running the SMT code on a !SMT part is basically a more
aggressive select_idle_cpu(). Removing the avg condition fixed things
for him.
I also know FB likes this test gone, even though other workloads like
having it.
For now, take it out by default, until we get a better idea.
Reported-by: kitsunyan <kitsunyan@inbox.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 2 | ||||
| -rw-r--r-- | kernel/sched/features.h | 5 |
2 files changed, 6 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 274c747a01ce..b3ee10dd3e85 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5797,7 +5797,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t * Due to large variance we need a large fuzz factor; hackbench in * particularly is sensitive here. */ - if ((avg_idle / 512) < avg_cost) + if (sched_feat(SIS_AVG_CPU) && (avg_idle / 512) < avg_cost) return -1; time = local_clock(); diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 69631fa46c2f..1b3c8189b286 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -51,6 +51,11 @@ SCHED_FEAT(NONTASK_CAPACITY, true) */ SCHED_FEAT(TTWU_QUEUE, true) +/* + * When doing wakeups, attempt to limit superfluous scans of the LLC domain. + */ +SCHED_FEAT(SIS_AVG_CPU, false) + #ifdef HAVE_RT_PUSH_IPI /* * In order to avoid a thundering herd attack of CPUs that are |