summaryrefslogtreecommitdiffstats
path: root/kernel/sched/features.h
diff options
context:
space:
mode:
authorPeter Zijlstra <peterz@infradead.org>2017-05-17 12:53:50 +0200
committerIngo Molnar <mingo@kernel.org>2017-06-08 10:25:17 +0200
commit1ad3aaf3fcd2444406628a19a9b9e0922b95e2d4 (patch)
treee3db01782e505b85244eeb7e799e535b9c7b319a /kernel/sched/features.h
parentsched/header: Remove leftover, obsolete comment (diff)
downloadlinux-1ad3aaf3fcd2444406628a19a9b9e0922b95e2d4.tar.xz
linux-1ad3aaf3fcd2444406628a19a9b9e0922b95e2d4.zip
sched/core: Implement new approach to scale select_idle_cpu()
Hackbench recently suffered a bunch of pain, first by commit: 4c77b18cf8b7 ("sched/fair: Make select_idle_cpu() more aggressive") and then by commit: c743f0a5c50f ("sched/fair, cpumask: Export for_each_cpu_wrap()") which fixed a bug in the initial for_each_cpu_wrap() implementation that made select_idle_cpu() even more expensive. The bug was that it would skip over CPUs when bits were consequtive in the bitmask. This however gave me an idea to fix select_idle_cpu(); where the old scheme was a cliff-edge throttle on idle scanning, this introduces a more gradual approach. Instead of stopping to scan entirely, we limit how many CPUs we scan. Initial benchmarks show that it mostly recovers hackbench while not hurting anything else, except Mason's schbench, but not as bad as the old thing. It also appears to recover the tbench high-end, which also suffered like hackbench. Tested-by: Matt Fleming <matt@codeblueprint.co.uk> 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: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hpa@zytor.com Cc: kitsunyan <kitsunyan@inbox.ru> Cc: linux-kernel@vger.kernel.org Cc: lvenanci@redhat.com Cc: riel@redhat.com Cc: xiaolong.ye@intel.com Link: http://lkml.kernel.org/r/20170517105350.hk5m4h4jb6dfr65a@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/features.h')
-rw-r--r--kernel/sched/features.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index dc4d1483b038..d3fb15555291 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -55,6 +55,7 @@ SCHED_FEAT(TTWU_QUEUE, true)
* When doing wakeups, attempt to limit superfluous scans of the LLC domain.
*/
SCHED_FEAT(SIS_AVG_CPU, false)
+SCHED_FEAT(SIS_PROP, true)
/*
* Issue a WARN when we do multiple update_rq_clock() calls