Re: [PATCH] Fix migration of SCHED_DEADLINE tasks

From	Juri Lelli <juri.lelli@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] Fix migration of SCHED_DEADLINE tasks
Date	2015-10-16 11:00 +0200
Message-ID	<qk91N-1e0-33@gated-at.bofh.it> (permalink)
References	<qjOA2-4Aq-19@gated-at.bofh.it> <qjTT3-3IL-1@gated-at.bofh.it> <qk8fo-hv-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi,

On 16/10/15 09:03, Luca Abeni wrote:
> On 10/15/2015 06:40 PM, Juri Lelli wrote:
>> On 15/10/15 12:09, Luca Abeni wrote:
>>> Commit 9d5142624256 ("sched/deadline: Reduce rq lock contention by
>>> eliminating locking of non-feasible target") broke select_task_rq_dl()
> [...]
>>> -                dl_time_before(p->dl.deadline,
>>> -                    cpu_rq(target)->dl.earliest_dl.curr))
>>> +                (dl_time_before(p->dl.deadline,
>>> +                    cpu_rq(target)->dl.earliest_dl.curr) ||
>>> +                (cpu_rq(target)->dl.earliest_dl.curr == 0)))
>>
>> Can't we actually use dl.dl_nr_running here and below, so
>> that we won't incur any wraparound problem?
> Ok, I tested the patch with dl.dl_nr_running and if works for me...
> 
> I am going to send the updated patch in few minutes.
> 

Thanks!

> BTW, should we also use "dl_rq->dl_nr_running == 0" instead of
> "dl_rq->earliest_dl.curr == 0" in inc_dl_deadline(), and remove the
> comment from init_dl_rq()? If you think it is a good idea, I'll test this
> additional change and send a patch in next week.
> 

Yeah, it seems we need that fix too.

Best,

- Juri

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[PATCH] Fix migration of SCHED_DEADLINE tasks Luca Abeni <luca.abeni@unitn.it> - 2015-10-15 13:10 +0200
  Re: [PATCH] Fix migration of SCHED_DEADLINE tasks Juri Lelli <juri.lelli@arm.com> - 2015-10-15 18:50 +0200
    Re: [PATCH] Fix migration of SCHED_DEADLINE tasks Luca Abeni <luca.abeni@unitn.it> - 2015-10-15 22:20 +0200
    Re: [PATCH] Fix migration of SCHED_DEADLINE tasks Luca Abeni <luca.abeni@unitn.it> - 2015-10-16 10:10 +0200
      Re: [PATCH] Fix migration of SCHED_DEADLINE tasks Juri Lelli <juri.lelli@arm.com> - 2015-10-16 11:00 +0200

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