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sched/numa: Fix off-by-one in capacity check 

Commit a43455a1d5 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>
This commit is contained in:
Rik van Riel 2014-08-04 13:23:27 -04:00 committed by Ingo Molnar
parent aaecac4ad4
commit b932c03c34
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/fair.c
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@ -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;