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

From	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Newsgroups	linux.kernel
Subject	Re: [RFC][PATCH 5/7] cpufreq / sched: UUF_IO flag to indicate iowait condition
Date	2016-08-06 23:20 +0200
Message-ID	<s3haG-2Dy-15@gated-at.bofh.it> (permalink)
References	<s18Ex-6NS-1@gated-at.bofh.it> <s2ydA-6EW-33@gated-at.bofh.it> <s2yZX-7nK-17@gated-at.bofh.it>
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On Thursday, August 04, 2016 03:09:08 PM Steve Muckle wrote:
> On Thu, Aug 04, 2016 at 11:19:00PM +0200, Rafael J. Wysocki wrote:

[cut]
 
> > > This is also an issue for the remote wakeup case where I currently have
> > > another invocation of the hook in check_preempt_curr(), so I can know if
> > > preemption was triggered and skip a remote schedutil update in that case
> > > to avoid a duplicate IPI.
> > > 
> > > It seems to me worth evaluating if a higher level set of hook locations
> > > could be used. One possibility is higher up in CFS:
> > > - enqueue_task_fair, dequeue_task_fair
> > > - scheduler_tick
> > > - active_load_balance_cpu_stop, load_balance
> > 
> > Agreed, that's worth checking.
> > 
> > > Though this wouldn't solve my issue with check_preempt_curr. That would
> > > probably require going further up the stack to try_to_wake_up() etc. Not
> > > yet sure what the other hook locations would be at that level.
> > 
> > That's probably too far away from the root cfs_rq utilization changes IMO.
> 
> Is your concern that the rate of hook calls would be decreased?

It might be decreased, but also we might end up using utilization values
that wouldn't reflect the current situation (eg. if the hook is called before
update_load_avg(), the util value used by the governor may not be adequate).

Thanks,
Rafael

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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