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authorKirill Tkhai <ktkhai@parallels.com>2014-10-21 20:35:56 +0400
committerIngo Molnar <mingo@kernel.org>2014-10-28 10:46:10 +0100
commitf3a7e1a9c464a32ee186ab91388313c82e7ce018 (patch)
tree74d90ab7172a01aa653b88570322eb900789a562
parentfcd964dda5ece2fa77f78f843bc3455348787282 (diff)
downloadlinux-f3a7e1a9c464a32ee186ab91388313c82e7ce018.tar.bz2
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>
-rw-r--r--kernel/sched/deadline.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 46167899d852..5285332392d5 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -540,7 +540,7 @@ again:
dl_se->dl_yielded = 0;
if (task_on_rq_queued(p)) {
enqueue_task_dl(rq, p, ENQUEUE_REPLENISH);
- if (task_has_dl_policy(rq->curr))
+ if (dl_task(rq->curr))
check_preempt_curr_dl(rq, p, 0);
else
resched_curr(rq);
@@ -1626,8 +1626,12 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
/* Only reschedule if pushing failed */
check_resched = 0;
#endif /* CONFIG_SMP */
- if (check_resched && task_has_dl_policy(rq->curr))
- check_preempt_curr_dl(rq, p, 0);
+ if (check_resched) {
+ if (dl_task(rq->curr))
+ check_preempt_curr_dl(rq, p, 0);
+ else
+ resched_curr(rq);
+ }
}
}