sched: Implement a gentler fair-sleepers feature
Add back FAIR_SLEEPERS and GENTLE_FAIR_SLEEPERS. FAIR_SLEEPERS is the old logic: credit sleepers with their sleep time. GENTLE_FAIR_SLEEPERS dampens this a bit: 50% of their sleep time gets credited. The hope here is to still give the benefits of fair-sleepers logic (quick wakeups, etc.) while not allow them to have 100% of their sleep time as if they were running. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -711,7 +711,7 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
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if (!initial) {
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if (!initial) {
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/* sleeps upto a single latency don't count. */
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/* sleeps upto a single latency don't count. */
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if (sched_feat(NEW_FAIR_SLEEPERS)) {
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if (sched_feat(FAIR_SLEEPERS)) {
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unsigned long thresh = sysctl_sched_latency;
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unsigned long thresh = sysctl_sched_latency;
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/*
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/*
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@ -725,6 +725,13 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
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task_of(se)->policy != SCHED_IDLE))
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task_of(se)->policy != SCHED_IDLE))
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thresh = calc_delta_fair(thresh, se);
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thresh = calc_delta_fair(thresh, se);
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/*
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* Halve their sleep time's effect, to allow
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* for a gentler effect of sleepers:
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*/
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if (sched_feat(GENTLE_FAIR_SLEEPERS))
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thresh >>= 1;
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vruntime -= thresh;
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vruntime -= thresh;
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}
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}
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}
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}
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@ -3,7 +3,14 @@
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* considers the task to be running during that period. This gives it
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* considers the task to be running during that period. This gives it
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* a service deficit on wakeup, allowing it to run sooner.
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* a service deficit on wakeup, allowing it to run sooner.
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*/
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*/
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SCHED_FEAT(NEW_FAIR_SLEEPERS, 0)
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SCHED_FEAT(FAIR_SLEEPERS, 1)
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/*
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* Only give sleepers 50% of their service deficit. This allows
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* them to run sooner, but does not allow tons of sleepers to
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* rip the spread apart.
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*/
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SCHED_FEAT(GENTLE_FAIR_SLEEPERS, 1)
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/*
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/*
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* By not normalizing the sleep time, heavy tasks get an effective
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* By not normalizing the sleep time, heavy tasks get an effective
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