sched/fair: Fix forced idle sibling starvation corner case

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If there is only one long running local task and the sibling is
forced idle, it  might not get a chance to run until a schedule
event happens on any cpu in the core.

So we check for this condition during a tick to see if a sibling
is starved and then give it a chance to schedule.

Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Don Hiatt <dhiatt@digitalocean.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123308.617407840@infradead.org

...

This commit is contained in:

Vineeth Pillai 2020-11-17 18:19:38 -05:00 • committed by Peter Zijlstra

parent 539f65125d

commit 8039e96fcc

3 changed files with 49 additions and 8 deletions

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15

kernel/sched/core.c

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40

kernel/sched/fair.c

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2

kernel/sched/sched.h

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