sched: clear buddies more aggressively
It was noticed that a task could get re-elected past its run quota due to buddy affinities. This could increase latency a little. Cure it by more aggresively clearing buddy state. We do so in two situations: - when we force preempt - when we select a buddy to run Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -768,8 +768,14 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
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ideal_runtime = sched_slice(cfs_rq, curr);
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ideal_runtime = sched_slice(cfs_rq, curr);
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delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
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delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
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if (delta_exec > ideal_runtime)
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if (delta_exec > ideal_runtime) {
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resched_task(rq_of(cfs_rq)->curr);
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resched_task(rq_of(cfs_rq)->curr);
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/*
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* The current task ran long enough, ensure it doesn't get
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* re-elected due to buddy favours.
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*/
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clear_buddies(cfs_rq, curr);
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}
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}
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}
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static void
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static void
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@ -1445,6 +1451,11 @@ static struct task_struct *pick_next_task_fair(struct rq *rq)
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do {
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do {
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se = pick_next_entity(cfs_rq);
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se = pick_next_entity(cfs_rq);
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/*
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* If se was a buddy, clear it so that it will have to earn
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* the favour again.
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*/
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clear_buddies(cfs_rq, se);
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set_next_entity(cfs_rq, se);
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set_next_entity(cfs_rq, se);
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cfs_rq = group_cfs_rq(se);
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cfs_rq = group_cfs_rq(se);
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} while (cfs_rq);
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} while (cfs_rq);
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