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Re: [PATCH 3/3 v5] cpufreq: governor: Replace timers with utilization update callbacks

From Gautham R Shenoy <ego@linux.vnet.ibm.com>
Newsgroups linux.kernel
Subject Re: [PATCH 3/3 v5] cpufreq: governor: Replace timers with utilization update callbacks
Date 2016-02-09 11:10 +0100
Message-ID <r0dp9-2Ab-9@gated-at.bofh.it> (permalink)
References <qWqbf-1BM-3@gated-at.bofh.it> <qYDnJ-1Cc-13@gated-at.bofh.it> <qZ22J-1rp-1@gated-at.bofh.it> <qZyYG-7x5-7@gated-at.bofh.it>
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Hello Rafael,

On Sun, Feb 07, 2016 at 03:50:31PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Instead of using a per-CPU deferrable timer for queuing up governor
> work items, register a utilization update callback that will be
> invoked from the scheduler on utilization changes.
> 
> The sampling rate is still the same as what was used for the
> deferrable timers and the added irq_work overhead should be offset by
> the eliminated timers overhead, so in theory the functional impact of
> this patch should not be significant.

I tested this patch series (including v5 of PATCH 3) on POWER with
Viresh's CPUFreq test suite. I didn't see any issues with the
patchset except for a lockdep splat involving "s_active" and
"od_dbs_cdata.mutex", which was also observed on 4.5-rc3 and which
was fixed by Viresh's recent patches. 

With a kernbench run, there were no regression when compared to 4.5-rc3.

FWIW, Tested-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>

> 
> Thanks,
> Rafael

--
Thanks and Regards
gautham.

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[PATCH 3/3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-01-30 00:00 +0100
  [Update][PATCH 3/3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-03 02:20 +0100
    Re: [Update][PATCH 3/3] cpufreq: governor: Replace timers with  utilization update callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-04 06:00 +0100
      Re: [Update][PATCH 3/3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-04 12:00 +0100
    [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-05 02:30 +0100
      Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with  utilization update callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-05 08:00 +0100
        Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization  update callbacks "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-05 14:40 +0100
          Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization  update callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-05 16:10 +0100
            Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-06 00:20 +0100
              Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with  utilization update callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-07 10:20 +0100
                Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-07 15:50 +0100
                Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-08 03:10 +0100
                Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with  utilization update callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-08 13:00 +0100
                Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization  update callbacks "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-08 14:00 +0100
                Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization  update callbacks "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-08 14:50 +0100
          Re: [PATCH 3/3 v3] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-06 00:10 +0100
      [PATCH 3/3 v4] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-06 04:50 +0100
        Re: [PATCH 3/3 v4] cpufreq: governor: Replace timers with  utilization update callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-07 10:30 +0100
          Re: [PATCH 3/3 v4] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-07 15:40 +0100
        [PATCH 3/3 v5] cpufreq: governor: Replace timers with utilization update callbacks "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-07 16:00 +0100
          Re: [PATCH 3/3 v5] cpufreq: governor: Replace timers with  utilization update callbacks Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-07 16:40 +0100
          Re: [PATCH 3/3 v5] cpufreq: governor: Replace timers with  utilization update callbacks Gautham R Shenoy <ego@linux.vnet.ibm.com> - 2016-02-09 11:10 +0100
            Re: [PATCH 3/3 v5] cpufreq: governor: Replace timers with utilization  update callbacks "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-09 19:50 +0100

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