Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data
Date	2016-03-10 09:50 +0100
Message-ID	<rb4sa-4iX-15@gated-at.bofh.it> (permalink)
References	(5 earlier) <rauf0-4va-33@gated-at.bofh.it> <ravuq-5iT-25@gated-at.bofh.it> <raw78-5OE-21@gated-at.bofh.it> <raPjs-24S-17@gated-at.bofh.it> <raVIg-6Sb-51@gated-at.bofh.it>
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On Thu, Mar 10, 2016 at 12:28:52AM +0100, Rafael J. Wysocki wrote:
> > [ I would not have chosen (1 + 1/n), but lets stick to that ]
> 
> Well, what would you choose then? :-)

1/p ; 0 < p < 1

or so. Where p then represents the percentile threshold where you want
to bump to the next freq.

> I think that should be
> 
>   next_freq = (1 + 1/n) * max_freq * util / max
> 
> (where max is the second argument of cpufreq_update_util) or the
> dimensions on both sides don't match.

Well yes, but so far we were treating util (and util_raw) as 0 < u < 1,
values, so already normalized against max.

But yes..

> > if we substitute (2) into (3) we get:
> >
> >                   = (1 + 1/n) * max_freq * util_raw * current_freq / max_freq
> >                   = (1 + 1/n) * current_freq * util_raw (4)
> >
> > Which gets you two formula with the same general behaviour. As (2) is
> > the only approximation of (1) we can make.
> 
> OK
> 
> So since utilization is not frequency invariant in the current
> mainline (or linux-next for that matter) AFAIC, I'm going to use the
> following in the next version of the schedutil patch series:
> 
>   next_freq = 1.25 * current_freq * util_raw / max
> 
> where util_raw and max are what I get from cpufreq_update_util().
> 
> 1.25 is for the 80% tipping point which I think is reasonable.

OK.

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Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-07 03:40 +0100
  Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-08 12:30 +0100
    Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-08 19:10 +0100
      Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-08 20:30 +0100
        Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-08 21:10 +0100
          Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Juri Lelli <juri.lelli@arm.com> - 2016-03-09 11:20 +0100
            Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-10 00:50 +0100
              Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Juri Lelli <juri.lelli@arm.com> - 2016-03-10 05:40 +0100
                Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-10 22:10 +0100
              Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Michael Turquette <mturquette@baylibre.com> - 2016-03-11 00:30 +0100
          Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-09 17:40 +0100
            Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-10 00:30 +0100
              Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-10 04:50 +0100
                Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-10 11:10 +0100
                Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Vincent Guittot <vincent.guittot@linaro.org> - 2016-03-10 11:30 +0100
                Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-10 11:40 +0100
                Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-10 12:00 +0100
                Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-10 23:30 +0100
              Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler  utilization data Peter Zijlstra <peterz@infradead.org> - 2016-03-10 09:50 +0100

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