Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg()

From	Vincent Guittot <vincent.guittot@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg()
Date	2016-03-31 15:00 +0200
Message-ID	<riKmD-5a4-35@gated-at.bofh.it> (permalink)
References	(6 earlier) <riHf4-2VE-23@gated-at.bofh.it> <riHyq-32C-17@gated-at.bofh.it> <riIkN-3DO-11@gated-at.bofh.it> <riJJU-4OT-13@gated-at.bofh.it> <riK3h-531-45@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 31 March 2016 at 14:34, Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, Mar 31, 2016 at 02:14:50PM +0200, Vincent Guittot wrote:
>> In fact, I looks for the sequence where the utilization of a rq is not
>> updated until the next tick but i can't find it.
>
> No, util it always updated, however..
>
>> If cpu doesn't share cache, task is added to wake list and an ipi is
>> sent and the utilization.
>
> Here we run:
>
>  ttwu_do_activate()
>    ttwu_activate()
>      activate_task()
>        enqueue_task()
>          p->sched_class->enqueue_task() := enqueue_task_fair()
>            update_load_avg()
>              update_cfs_rq_load_avg()
>                cfs_rq_util_change()
>
> On the local cpu, and we can indeed call out to have the frequency
> changed.
>
>> Otherwise, we directly enqueue the task on
>> the rq and the utilization is updated
>
> But here we run it on a remote cpu, so we cannot call out and the
> frequency remains the same.
>
> So if a remote wakeup on the same LLC domain happens, utilization will
> increase but we will not observe until the next tick.

ok. I forgot that we have the condition cpu == smp_processor_id() in
cfs_rq_util_change.

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg() Steve Muckle <steve.muckle@linaro.org> - 2016-03-22 01:30 +0100
  Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Steve Muckle <steve.muckle@linaro.org> - 2016-03-28 18:40 +0200
    Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Steve Muckle <steve.muckle@linaro.org> - 2016-03-28 21:40 +0200
      Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Peter Zijlstra <peterz@infradead.org> - 2016-03-30 21:40 +0200
        Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Steve Muckle <steve.muckle@linaro.org> - 2016-03-31 03:50 +0200
          Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Peter Zijlstra <peterz@infradead.org> - 2016-03-31 09:40 +0200
            Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Steve Muckle <steve.muckle@linaro.org> - 2016-03-31 23:30 +0200
              Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Peter Zijlstra <peterz@infradead.org> - 2016-04-01 11:30 +0200
        Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg() Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-31 11:30 +0200
          Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Peter Zijlstra <peterz@infradead.org> - 2016-03-31 11:40 +0200
            Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg() Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-31 12:00 +0200
              Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Peter Zijlstra <peterz@infradead.org> - 2016-03-31 12:50 +0200
                Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg() Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-31 14:20 +0200
                Re: [PATCH 1/2] sched/fair: move cpufreq hook to  update_cfs_rq_load_avg() Peter Zijlstra <peterz@infradead.org> - 2016-03-31 14:40 +0200
                Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg() Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-31 15:00 +0200

csiph-web