Messages in this thread Patch in this message | | | Date | Thu, 7 Sep 2017 01:16:24 -0700 | From | tip-bot for Peter Zijlstra <> | Subject | [tip:sched/urgent] sched/fair: Fix wake_affine_llc() balancing rules |
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Commit-ID: a731ebe6f17bff9e7ca12ef227f9da4d5bdf8425 Gitweb: http://git.kernel.org/tip/a731ebe6f17bff9e7ca12ef227f9da4d5bdf8425 Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Wed, 6 Sep 2017 12:51:31 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Thu, 7 Sep 2017 09:29:31 +0200
sched/fair: Fix wake_affine_llc() balancing rules
Chris Wilson reported that the SMT balance rules got the +1 on the wrong side, resulting in a bias towards the current LLC; which the load-balancer would then try and undo.
Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Tested-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> 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: linux-kernel@vger.kernel.org Fixes: 90001d67be2f ("sched/fair: Fix wake_affine() for !NUMA_BALANCING") Link: http://lkml.kernel.org/r/20170906105131.gqjmaextmn3u6tj2@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8d58687..9dd2ce1 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5435,7 +5435,7 @@ wake_affine_llc(struct sched_domain *sd, struct task_struct *p, return false; /* if this cache has capacity, come here */ - if (this_stats.has_capacity && this_stats.nr_running < prev_stats.nr_running+1) + if (this_stats.has_capacity && this_stats.nr_running+1 < prev_stats.nr_running) return true; /*
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