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RE: [PATCH] sched: fix task and run queue run_delay inconsistencies

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> From: Peter Zijlstra [mailto:peterz@infradead.org]
>
> On Wed, Sep 23, 2015 at 12:37:18AM +0000, Meyer, Mike wrote:
> >
> > The proposed patch addresses the issue by calling
> > sched_info_reset_dequeued(thread) following the call to
> > enqueue_task(rq, thread) for running threads in situations in which
> > thread->sched_info.last_queued should remain 0.
> 
> Would something like the below; which avoids calling
> sched_info_{de,}queued() for these sites also work?
> 
> It even shrinks the code (due to inlining {en,de}queue_task()):
> 
> $ size defconfig-build/kernel/sched/core.o defconfig-
> build/kernel/sched/core.o.orig
>    text    data     bss     dec     hex filename
>   64019   23378    2344   89741   15e8d defconfig-build/kernel/sched/core.o
>   64149   23378    2344   89871   15f0f defconfig-build/kernel/sched/core.o.orig
> 
Yes that will also address the issue.

The reason I approached the way I did was to avoid adding code path to the far more common uses of {en,de}queue_task() but I doubt anyone is going to notice a difference with the addition of some register save/restores and a compare in that path.  Overall the code does shrink with the alternative which is good.

My only comment is I am not sure about the naming of the flag ENQUEUE_TEMP which implies (to me) the enqueue is temporary which clearly it isn't.    Maybe something like DEQUEUE_MOVE/ENQUEUE_MOVE would be a bit more descriptive of the use case.

Other than that I am fine with what you proposed.

Thanks!


 
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[PATCH] sched: fix task and run queue run_delay inconsistencies "Meyer, Mike" <Mike.Meyer@Teradata.com> - 2015-09-23 03:10 +0200
  Re: [PATCH] sched: fix task and run queue run_delay inconsistencies Peter Zijlstra <peterz@infradead.org> - 2015-09-30 17:50 +0200
    RE: [PATCH] sched: fix task and run queue run_delay inconsistencies "Meyer, Mike" <Mike.Meyer@Teradata.com> - 2015-09-30 22:30 +0200
      Re: [PATCH] sched: fix task and run queue run_delay inconsistencies Peter Zijlstra <peterz@infradead.org> - 2015-10-01 08:40 +0200
        Re: [PATCH] sched: fix task and run queue run_delay inconsistencies Peter Zijlstra <peterz@infradead.org> - 2015-10-01 11:50 +0200
          RE: [PATCH] sched: fix task and run queue run_delay inconsistencies "Meyer, Mike" <Mike.Meyer@Teradata.com> - 2015-10-01 18:10 +0200

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