[RFC][PATCH 0/7] cpufreq / sched: cpufreq_update_util() flags and iowait boosting

From	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Newsgroups	linux.kernel
Subject	[RFC][PATCH 0/7] cpufreq / sched: cpufreq_update_util() flags and iowait boosting
Date	2016-08-01 01:50 +0200
Message-ID	<s18Ex-6NS-1@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hi,

Admittedly, this hasn't been tested yet, so no promises and you have been
warned.  It builds, though (on x86-64 at least).

At this point I'm looking for general feedback mostly: does the direction make
sense or is there any reason why it can't work (that I'm not seeing), is it
acceptable and if not, how can it be improved?

Of course, if you don't like the details, please let me know too. :-)

This is based on Peter's suggestions and Srinivas's research.

The ultimate goal is to improve performance for tasks that have been waiting
on I/O in the schedutil governor and to provide a better default P-state
selection algorithm for intel_pstate (which also involves taking the "iowait"
into account).  The steps to get there are the following:

[1] Drop the util and max arguments from cpufreq_update_util() and the ->func()
    callback in struct update_util_data and make the schedutil governor access
    the scheduler's utilization data directly (this one is originally from Peter,
    I did my best to avoid breaking it).
[2] Drop cpufreq_trigger_update() as it is the same as cpufreq_update_util()
    after [1].
[3] Pass rq to cpufreq_update_util() (instead of the time) and make it do the
    smp_processor_id() check.
[4] Add a flags argument to cpufreq_update_util() and the ->func() callback in
    struct update_util_data, update their users accordingly and use the flags
    to clean up the handling of util updates from the RT sched class a bit.
[5] Make enqueue_task_fair() pass a new "IO" flag to cpufreq_update_util()
    if p->in_iowait is set.
[6] Modify the schedutil governor to use the new "IO" flag for boosting CPU
    frequency temporarily (in order to improve performance for tasks that
    have been waiting on I/O).
[7] Add a new P-state selection algorithm, based on "busy fraction" computation
    and "IO" boosting, and use it by default for Core processors.

Thanks,
Rafael

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[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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