mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2025-01-10 07:00:48 +00:00
4c77b18cf8
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>
77 lines
2.0 KiB
C
77 lines
2.0 KiB
C
/*
|
|
* Only give sleepers 50% of their service deficit. This allows
|
|
* them to run sooner, but does not allow tons of sleepers to
|
|
* rip the spread apart.
|
|
*/
|
|
SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
|
|
|
|
/*
|
|
* Place new tasks ahead so that they do not starve already running
|
|
* tasks
|
|
*/
|
|
SCHED_FEAT(START_DEBIT, true)
|
|
|
|
/*
|
|
* Prefer to schedule the task we woke last (assuming it failed
|
|
* wakeup-preemption), since its likely going to consume data we
|
|
* touched, increases cache locality.
|
|
*/
|
|
SCHED_FEAT(NEXT_BUDDY, false)
|
|
|
|
/*
|
|
* Prefer to schedule the task that ran last (when we did
|
|
* wake-preempt) as that likely will touch the same data, increases
|
|
* cache locality.
|
|
*/
|
|
SCHED_FEAT(LAST_BUDDY, true)
|
|
|
|
/*
|
|
* Consider buddies to be cache hot, decreases the likelyness of a
|
|
* cache buddy being migrated away, increases cache locality.
|
|
*/
|
|
SCHED_FEAT(CACHE_HOT_BUDDY, true)
|
|
|
|
/*
|
|
* Allow wakeup-time preemption of the current task:
|
|
*/
|
|
SCHED_FEAT(WAKEUP_PREEMPTION, true)
|
|
|
|
SCHED_FEAT(HRTICK, false)
|
|
SCHED_FEAT(DOUBLE_TICK, false)
|
|
SCHED_FEAT(LB_BIAS, true)
|
|
|
|
/*
|
|
* Decrement CPU capacity based on time not spent running tasks
|
|
*/
|
|
SCHED_FEAT(NONTASK_CAPACITY, true)
|
|
|
|
/*
|
|
* Queue remote wakeups on the target CPU and process them
|
|
* using the scheduler IPI. Reduces rq->lock contention/bounces.
|
|
*/
|
|
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
|
|
* lowering their priorities at the same time, and there being
|
|
* a single CPU that has an RT task that can migrate and is waiting
|
|
* to run, where the other CPUs will try to take that CPUs
|
|
* rq lock and possibly create a large contention, sending an
|
|
* IPI to that CPU and let that CPU push the RT task to where
|
|
* it should go may be a better scenario.
|
|
*/
|
|
SCHED_FEAT(RT_PUSH_IPI, true)
|
|
#endif
|
|
|
|
SCHED_FEAT(FORCE_SD_OVERLAP, false)
|
|
SCHED_FEAT(RT_RUNTIME_SHARE, true)
|
|
SCHED_FEAT(LB_MIN, false)
|
|
SCHED_FEAT(ATTACH_AGE_LOAD, true)
|
|
|