Commit 096aa338 authored May 16, 2014 by Rik van Riel Committed by Ingo Molnar May 22, 2014

sched/numa: Decay ->wakee_flips instead of zeroing



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>

parent b1ad065e

kernel/sched/fair.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;
		}