linux-kernel - Re: [PATCH] sched/deadline: do not try to push tasks if pinned task switches to dl

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Date:	Fri, 10 Oct 2014 19:00:55 +0800
From:	Wanpeng Li <kernellwp@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@....com>,
	Kirill V Tkhai <tkhai@...dex.ru>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/deadline: do not try to push tasks if pinned task
 switches to dl


于 10/10/14, 6:56 PM, Peter Zijlstra 写道:
> On Fri, Oct 10, 2014 at 06:26:42PM +0800, Wanpeng Li wrote:
>> 于 10/10/14, 6:10 PM, Peter Zijlstra 写道:
>>> On Fri, Oct 10, 2014 at 10:43:17AM +0800, Wanpeng Li wrote:
>>>> As Kirill mentioned(https://lkml.org/lkml/2013/1/29/118):
>>>> | If rq has already had 2 or more pushable tasks and we try to add a
>>>> | pinned task then call of push_rt_task will just waste a time.
>>>>
>>>> Just switched pinned task is not able to be pushed. If the rq had had
>>>> several dl tasks before they have already been considered as candidates
>>>> to be pushed (or pulled). This patch does the same behavior as rt class
>>>> which introduced by commit 104479 (sched/rt: Do not try to push tasks
>>>> if pinned task switches to RT).
>>> Checkpatch rightly complains:
>>>
>>> ERROR: Please use 12 or more chars for the git commit ID like: 'commit 10447917551e ("sched/rt: Do not try to push tasks if pinned task switches to RT")'
>>> #12:
>>> which introduced by commit 104479 (sched/rt: Do not try to push tasks
>> I also got this warning before send out the patch, however, I check 6 chars
>> is enough for this commit. Anyway, I will send a newer version later.
> It is currently, it might not be in the future. I've already had hash
> collisions with 8 char hashes. And the fact thats it in the changelog
> means it can (and therefore) will be referenced at some point in the
> future. If by that point there is a collision...

Got it, thanks for your pointing out.

Regards,
Wanpeng Li


View attachment "0001-sched-deadline-do-not-try-to-push-tasks-if-pinned-ta.patch" of type "text/plain" (1540 bytes)