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sched/deadline: Fix hrtick for a non-leftmost task 

After update_curr_dl() the current task might not be the leftmost task
anymore. In that case do not start a new hrtick for it.

In this case NEED_RESCHED will be set and the next schedule will start
the hrtick for the new task if and when appropriate.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Acked-by: Juri Lelli <juri.lelli@arm.com>
[ Rewrote the changelog and comment. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1416962647-76792-2-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Wanpeng Li 2014-11-26 08:44:01 +08:00 committed by Ingo Molnar
parent 4c195c8a19
commit a7bebf4887
1 changed files with 7 additions and 1 deletions
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8
kernel/sched/deadline.c
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@ -1073,7 +1073,13 @@ static void task_tick_dl(struct rq *rq, struct task_struct *p, int queued)
{
update_curr_dl(rq);
if (hrtick_enabled(rq) && queued && p->dl.runtime > 0)
/*
* Even when we have runtime, update_curr_dl() might have resulted in us
* not being the leftmost task anymore. In that case NEED_RESCHED will
* be set and schedule() will start a new hrtick for the next task.
*/
if (hrtick_enabled(rq) && queued && p->dl.runtime > 0 &&
is_leftmost(p, &rq->dl))
start_hrtick_dl(rq, p);
}