Messages in this thread Patch in this message | | | Date | Tue, 12 Aug 2014 07:53:05 -0700 | From | tip-bot for Rik van Riel <> | Subject | [tip:sched/core] sched/numa: Fix off-by-one in capacity check |
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Commit-ID: b932c03c34f3b03c7364c06aa8cae5b74609fc41 Gitweb: http://git.kernel.org/tip/b932c03c34f3b03c7364c06aa8cae5b74609fc41 Author: Rik van Riel <riel@redhat.com> AuthorDate: Mon, 4 Aug 2014 13:23:27 -0400 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Tue, 12 Aug 2014 12:48:22 +0200
sched/numa: Fix off-by-one in capacity check
Commit a43455a1d572daf7b730fe12eb747d1e17411365 ensures that task_numa_migrate will call task_numa_compare on the preferred node all the time, even when the preferred node has no free capacity.
This could lead to a performance regression if nr_running == capacity on both the source and the destination node. This can be avoided by also checking for nr_running == capacity on the source node, which is one stricter than checking .has_free_capacity.
Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: mgorman@suse.de Cc: vincent.guittot@linaro.org Cc: Morten.Rasmussen@arm.com Cc: nicolas.pitre@linaro.org Cc: efault@gmx.de Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1407173008-9334-2-git-send-email-riel@redhat.com 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 df1ed17..e1cf419 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1206,7 +1206,7 @@ static void task_numa_compare(struct task_numa_env *env, if (!cur) { /* Is there capacity at our destination? */ - if (env->src_stats.has_free_capacity && + if (env->src_stats.nr_running <= env->src_stats.task_capacity && !env->dst_stats.has_free_capacity) goto unlock;
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