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sched/numa: Decay ->wakee_flips instead of zeroing

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Affine wakeups have the potential to interfere with NUMA placement.
If a task wakes up too many other tasks, affine wakeups will get
disabled.

However, regardless of how many other tasks it wakes up, it gets
re-enabled once a second, potentially interfering with NUMA
placement of other tasks.

By decaying wakee_wakes in half instead of zeroing it, we can avoid
that problem for some workloads.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: chegu_vinod@hp.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20140516001332.67f91af2@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Rik van Riel 2014-05-16 00:13:32 -04:00 committed by Ingo Molnar
parent b1ad065e65
commit 096aa33863
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/fair.c
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@ -4065,7 +4065,7 @@ static void record_wakee(struct task_struct *p)
* about the loss.
*/
if (jiffies > current->wakee_flip_decay_ts + HZ) {
current->wakee_flips = 0;
current->wakee_flips >>= 1;
current->wakee_flip_decay_ts = jiffies;
}