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SubjectRe: [PATCH 4/7] sched/deadline: reschedule if stop task slip in after pull operations
On Tue, Apr 21, 2015 at 06:59:02AM +0800, Wanpeng Li wrote:
>Hi Juri,
>On Mon, Apr 20, 2015 at 11:27:22AM +0100, Juri Lelli wrote:
>>Hi,
>>
>>On 06/04/2015 09:53, 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.
>>>
>>
>>Ok, I guess it can happen. Doesn't RT have the same problem? It seems that
>>it also has to deal with DL tasks slipping in, right?
>
>Yeah, I will send another patch to handle RT class in the v2 patchset. :)

Oh, I just find I have already done them in patch 7/7.

Regards,
Wanpeng Li

>
>Regards,
>Wanpeng Li
>
>>
>>Thanks,
>>
>>- Juri
>>
>>> 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 b8b9355..844da0f 100644
>>> --- a/kernel/sched/deadline.c
>>> +++ b/kernel/sched/deadline.c
>>> @@ -1739,7 +1739,13 @@ 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);
>>> }
>>>
>>> @@ -1786,6 +1792,14 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
>>> 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 (rq->stop && task_on_rq_queued(rq->stop))
>>> + resched_curr(rq);
>>> +
>>> + /*
>>> * If we now have a earlier deadline task than p,
>>> * then reschedule, provided p is still on this
>>> * runqueue.
>>>


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