Messages in this thread | | | Date | Sun, 31 May 2015 08:06:16 +0800 | From | Wanpeng Li <> | Subject | Re: [PATCH v2 4/7] sched/deadline: reschedule if stop task slip in after pull operations |
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On 5/29/15 10:16 PM, Peter Zijlstra wrote: > On Wed, May 13, 2015 at 02:01:04PM +0800, Wanpeng Li wrote: >> pull_dl_task can drop (and re-acquire) rq->lock, this means a stop task >> can slip in, in which case we need to reschedule. This patch add the >> reschedule when the scenario occurs. >> >> Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com> >> --- >> kernel/sched/deadline.c | 16 +++++++++++++++- >> 1 file changed, 15 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c >> index e49b1e6..7d4c4fc 100644 >> --- a/kernel/sched/deadline.c >> +++ b/kernel/sched/deadline.c >> @@ -1750,7 +1750,13 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p) >> if (!task_on_rq_queued(p) || rq->dl.dl_nr_running) >> return; >> >> - if (pull_dl_task(rq)) >> + /* >> + * pull_dl_task() can drop (and re-acquire) rq->lock; this >> + * means a stop task can slip in, in which case we need to >> + * reschedule. >> + */ >> + if (pull_dl_task(rq) || >> + (rq->stop && task_on_rq_queued(rq->stop))) >> resched_curr(rq); > But, the waking of the stop task will already have done the preemption > check and won (obviously). So the wakeup should already have done the > resched_curr().
Indeed, thanks for your pointing out. :)
> > So why? > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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