Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg
Date	2017-05-01 18:00 +0200
Message-ID	<tClTX-2yI-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <tzSCK-37e-15@gated-at.bofh.it> <tAzHH-5SI-7@gated-at.bofh.it> <tAE4G-mI-15@gated-at.bofh.it> <tAMYi-6lN-9@gated-at.bofh.it> <tBkQh-4e7-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Apr 28, 2017 at 04:33:47PM -0400, Tejun Heo wrote:
> I'm attaching the debug patch.  With your change (avg instead of
> runnable_avg), the following trace shows why it's wrong.

Ah, OK. So you really want runnable_avg (and I understand why), which is
rather unfortunate, since we have everything on load_avg.

So for shares, load_avg gives a more stable number. This is important
since tg->load_avg is a global number, so computing it is expensive (and
slow). Therefore more stable numbers are good.

> The thing with cfs_rq se's load_avg is that, it isn't really used
> anywhere else AFAICS, so overriding it to the cfs_rq's
> runnable_load_avg isn't prettiest but doesn't really change anything.

You mean, consistently expressing a group's se->load.weight in terms of
runnable_load_avg? See the above.

Thread

Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-04-26 20:20 +0200
  Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-04-27 01:00 +0200
    Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-04-27 10:30 +0200
      Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-04-28 22:40 +0200
        Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-04-28 22:40 +0200
        Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Peter Zijlstra <peterz@infradead.org> - 2017-05-01 18:00 +0200
          Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-05-03 00:10 +0200
        Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-02 09:20 +0200
          Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-02 15:30 +0200
            Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-05-03 00:40 +0200
          Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-05-03 00:00 +0200
            Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-03 09:40 +0200
              Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Peter Zijlstra <peterz@infradead.org> - 2017-05-03 11:40 +0200
                Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-03 12:40 +0200
                Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Peter Zijlstra <peterz@infradead.org> - 2017-05-03 15:20 +0200
                Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-05-03 23:50 +0200
                Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-04 10:30 +0200
                Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-05-04 19:50 +0200
                Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Vincent Guittot <vincent.guittot@linaro.org> - 2017-05-04 21:10 +0200
                Re: [PATCH 2/2] sched/fair: Always propagate runnable_load_avg Tejun Heo <tj@kernel.org> - 2017-05-04 21:10 +0200

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