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SubjectRe: [PATCH 4/7] sched/deadline: reschedule if stop task slip in after pull operations
On 21/04/15 00:02, Wanpeng Li wrote:
> 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.
>

Oh, right! That one ended up in another bucket. Sorry about that.

Best,

- Juri

> 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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