Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition

From	Steve Muckle <steve.muckle@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition
Date	2016-08-03 00:30 +0200
Message-ID	<s1Qmd-2er-13@gated-at.bofh.it> (permalink)
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On Tue, Aug 02, 2016 at 03:37:02AM +0200, Rafael J. Wysocki wrote:
> On Tue, Aug 2, 2016 at 3:22 AM, Steve Muckle <steve.muckle@linaro.org> wrote:
> > On Mon, Aug 01, 2016 at 01:37:23AM +0200, Rafael J. Wysocki wrote:
> > ...
> >> For this purpose, define a new cpufreq_update_util() flag
> >> UUF_IO and modify enqueue_task_fair() to pass that flag to
> >> cpufreq_update_util() in the in_iowait case.  That generally
> >> requires cpufreq_update_util() to be called directly from there,
> >> because update_load_avg() is not likely to be invoked in that
> >> case.
> >
> > I didn't follow why the cpufreq hook won't likely be called if
> > in_iowait is set? AFAICS update_load_avg() gets called in the second loop
> > and calls update_cfs_rq_load_avg (triggers the hook).
> 
> In practice it turns out that in the majority of cases when in_iowait
> is set the second loop will not run.

My understanding of enqueue_task_fair() is that the first loop walks up
the portion of the sched_entity hierarchy that needs to be enqueued, and
the second loop updates the rest of the hierarchy that was already
enqueued.

Even if the se corresponding to the root cfs_rq needs to be enqueued
(meaning the whole hierarchy is traversed in the first loop and the
second loop does nothing), enqueue_entity() on the root cfs_rq should
result in the cpufreq hook being called, via enqueue_entity() ->
enqueue_entity_load_avg() -> update_cfs_rq_load_avg().

I'll keep looking to see if I've misunderstood something in here.

thanks,
Steve

Thread

[RFC][PATCH 0/7] cpufreq / sched: cpufreq_update_util() flags and iowait boosting "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
  [RFC][PATCH 4/7] cpufreq / sched: Add flags argument to cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
    Re: [RFC][PATCH 4/7] cpufreq / sched: Add flags argument to  cpufreq_update_util() Dominik Brodowski <linux@dominikbrodowski.net> - 2016-08-01 10:00 +0200
      Re: [RFC][PATCH 4/7] cpufreq / sched: Add flags argument to cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 17:10 +0200
        Re: [RFC][PATCH 4/7] cpufreq / sched: Add flags argument to  cpufreq_update_util() Steve Muckle <steve.muckle@linaro.org> - 2016-08-01 22:30 +0200
          Re: [RFC][PATCH 4/7] cpufreq / sched: Add flags argument to cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-02 01:50 +0200
            Re: [RFC][PATCH 4/7] cpufreq / sched: Add flags argument to  cpufreq_update_util() Steve Muckle <steve.muckle@linaro.org> - 2016-08-02 04:10 +0200
  [RFC][PATCH 3/7] cpufreq / sched: Check cpu_of(rq) in cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
    Re: [RFC][PATCH 3/7] cpufreq / sched: Check cpu_of(rq) in  cpufreq_update_util() Dominik Brodowski <linux@dominikbrodowski.net> - 2016-08-01 10:00 +0200
      Re: [RFC][PATCH 3/7] cpufreq / sched: Check cpu_of(rq) in cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 17:10 +0200
      Re: [RFC][PATCH 3/7] cpufreq / sched: Check cpu_of(rq) in  cpufreq_update_util() Steve Muckle <steve.muckle@linaro.org> - 2016-08-01 21:50 +0200
        Re: [RFC][PATCH 3/7] cpufreq / sched: Check cpu_of(rq) in cpufreq_update_util() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-02 01:50 +0200
  [RFC][PATCH 1/7] cpufreq / sched: Make schedutil access utilization data directly "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
    Re: [RFC][PATCH 1/7] cpufreq / sched: Make schedutil access  utilization data directly Steve Muckle <steve.muckle@linaro.org> - 2016-08-01 21:40 +0200
      Re: [RFC][PATCH 1/7] cpufreq / sched: Make schedutil access utilization data directly "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-02 02:10 +0200
        Re: [RFC][PATCH 1/7] cpufreq / sched: Make schedutil access  utilization data directly Juri Lelli <juri.lelli@arm.com> - 2016-08-02 12:40 +0200
          Re: [RFC][PATCH 1/7] cpufreq / sched: Make schedutil access  utilization data directly Steve Muckle <steve.muckle@linaro.org> - 2016-08-02 16:40 +0200
            Re: [RFC][PATCH 1/7] cpufreq / sched: Make schedutil access  utilization data directly Juri Lelli <juri.lelli@arm.com> - 2016-08-02 17:00 +0200
        Re: [RFC][PATCH 1/7] cpufreq / sched: Make schedutil access  utilization data directly Peter Zijlstra <peterz@infradead.org> - 2016-08-08 12:40 +0200
  [RFC][PATCH 2/7] cpufreq / sched: Drop cpufreq_trigger_update() "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
  [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
    Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait  condition Steve Muckle <steve.muckle@linaro.org> - 2016-08-02 03:30 +0200
      Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition "Rafael J. Wysocki" <rafael@kernel.org> - 2016-08-02 03:50 +0200
        Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait  condition Steve Muckle <steve.muckle@linaro.org> - 2016-08-03 00:30 +0200
          Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition "Rafael J. Wysocki" <rafael@kernel.org> - 2016-08-03 00:50 +0200
            Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait  condition Steve Muckle <steve.muckle@linaro.org> - 2016-08-04 04:30 +0200
              Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-04 23:20 +0200
                Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait  condition Steve Muckle <steve.muckle@linaro.org> - 2016-08-05 00:10 +0200
                Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-06 23:20 +0200
  [RFC][PATCH 7/7] cpufreq: intel_pstate: Change P-state selection algorithm for Core "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
    RE: [RFC][PATCH 7/7] cpufreq: intel_pstate: Change P-state selection algorithm for Core "Doug Smythies" <dsmythies@telus.net> - 2016-08-04 09:00 +0200
      Re: [RFC][PATCH 7/7] cpufreq: intel_pstate: Change P-state selection algorithm for Core "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-06 23:50 +0200
        RE: [RFC][PATCH 7/7] cpufreq: intel_pstate: Change P-state selection algorithm for Core "Doug Smythies" <dsmythies@telus.net> - 2016-08-09 19:20 +0200
  [RFC][PATCH 6/7] cpufreq: schedutil: Add iowait boosting "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 01:50 +0200
    Re: [RFC][PATCH 6/7] cpufreq: schedutil: Add iowait boosting Steve Muckle <steve.muckle@linaro.org> - 2016-08-02 03:40 +0200
      Re: [RFC][PATCH 6/7] cpufreq: schedutil: Add iowait boosting "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-03 01:00 +0200
  RE: [RFC][PATCH 0/7] cpufreq / sched: cpufreq_update_util() flags and iowait boosting "Doug Smythies" <dsmythies@telus.net> - 2016-08-01 17:30 +0200
    Re: [RFC][PATCH 0/7] cpufreq / sched: cpufreq_update_util() flags and iowait boosting "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-01 18:30 +0200
      Re: [RFC][PATCH 0/7] cpufreq / sched: cpufreq_update_util() flags  and iowait boosting Peter Zijlstra <peterz@infradead.org> - 2016-08-08 13:10 +0200
        Re: [RFC][PATCH 0/7] cpufreq / sched: cpufreq_update_util() flags and iowait boosting "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-08 15:00 +0200

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