sched/fair: Add cfs_rq::avg_vruntime

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In order to move to an eligibility based scheduling policy, we need
to have a better approximation of the ideal scheduler.

Specifically, for a virtual time weighted fair queueing based
scheduler the ideal scheduler will be the weighted average of the
individual virtual runtimes (math in the comment).

As such, compute the weighted average to approximate the ideal
scheduler -- note that the approximation is in the individual task
behaviour, which isn't strictly conformant.

Specifically consider adding a task with a vruntime left of center, in
this case the average will move backwards in time -- something the
ideal scheduler would of course never do.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.654144274@infradead.org

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Peter Zijlstra 2023-05-31 13:58:40 +02:00 • committed by Ingo Molnar

parent 752182b24b

commit af4cf40470

3 changed files with 154 additions and 20 deletions

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32

kernel/sched/debug.c

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137

kernel/sched/fair.c

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5

kernel/sched/sched.h

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