Re: [PATCH] Fix migration of SCHED_DEADLINE tasks

From	Luca Abeni <luca.abeni@unitn.it>
Newsgroups	linux.kernel
Subject	Re: [PATCH] Fix migration of SCHED_DEADLINE tasks
Date	2015-10-16 10:10 +0200
Message-ID	<qk8fo-hv-13@gated-at.bofh.it> (permalink)
References	<qjOA2-4Aq-19@gated-at.bofh.it> <qjTT3-3IL-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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.

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.



				Thanks,
					Luca
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Thread

[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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