sched/dl: Fix preemption checks
1) switched_to_dl() check is wrong. We reschedule only if rq->curr is deadline task, and we do not reschedule if it's a lower priority task. But we must always preempt a task of other classes. 2) dl_task_timer(): Policy does not change in case of priority inheritance. rt_mutex_setprio() changes prio, while policy remains old. So we lose some balancing logic in dl_task_timer() and switched_to_dl() when we check policy instead of priority. Boosted task may be rq->curr. (I didn't change switched_from_dl() because no check is necessary there at all). I've looked at this place(switched_to_dl) several times and even fixed this function, but found just now... I suppose some performance tests may work better after this. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1413909356.19914.128.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -540,7 +540,7 @@ again:
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dl_se->dl_yielded = 0;
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if (task_on_rq_queued(p)) {
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enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
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if (task_has_dl_policy(rq->curr))
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if (dl_task(rq->curr))
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check_preempt_curr_dl(rq, p, 0);
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else
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resched_curr(rq);
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@ -1626,8 +1626,12 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
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/* Only reschedule if pushing failed */
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check_resched = 0;
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#endif /* CONFIG_SMP */
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if (check_resched && task_has_dl_policy(rq->curr))
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check_preempt_curr_dl(rq, p, 0);
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if (check_resched) {
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if (dl_task(rq->curr))
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check_preempt_curr_dl(rq, p, 0);
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else
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resched_curr(rq);
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}
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}
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}
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