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sched/deadline: Do not try to push tasks if pinned task switches to dl

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As Kirill mentioned (https://lkml.org/lkml/2013/1/29/118):

 | If rq has already had 2 or more pushable tasks and we try to add a
 | pinned task then call of push_rt_task will just waste a time.

Just switched pinned task is not able to be pushed. If the rq has had
several dl tasks before they have already been considered as candidates
to be pushed (or pulled). This patch implements the same behavior as rt
class which introduced by commit 1044791755 ("sched/rt: Do not try to
push tasks if pinned task switches to RT").

Suggested-by: Kirill V Tkhai <tkhai@yandex.ru>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1413938203-224610-1-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Wanpeng Li 2014-10-22 08:36:43 +08:00 committed by Ingo Molnar
parent e2336f6e51
commit d9aade7ae1
1 changed files with 2 additions and 1 deletions
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3
kernel/sched/deadline.c
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@ -1622,7 +1622,8 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p)
if (task_on_rq_queued(p) && rq->curr != p) {
#ifdef CONFIG_SMP
if (rq->dl.overloaded && push_dl_task(rq) && rq != task_rq(p))
if (p->nr_cpus_allowed > 1 && rq->dl.overloaded &&
push_dl_task(rq) && rq != task_rq(p))
/* Only reschedule if pushing failed */
check_resched = 0;
#endif /* CONFIG_SMP */