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Re: [PATCH 2/4 v2] x86: use common aperfmperf_khz_on_cpu() to calculate KHz using APERF/MPERF

From "Rafael J. Wysocki" <rafael@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH 2/4 v2] x86: use common aperfmperf_khz_on_cpu() to calculate KHz using APERF/MPERF
Date 2017-06-24 14:10 +0200
Message-ID <tVS2Z-7DX-5@gated-at.bofh.it> (permalink)
References <tVLEd-3Fl-3@gated-at.bofh.it> <tVLEe-3Fl-15@gated-at.bofh.it> <tVP58-5Dp-19@gated-at.bofh.it>
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On Sat, Jun 24, 2017 at 10:56 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Fri, 23 Jun 2017, Len Brown wrote:
>> This x86 native method to calculate MHz returns a meaningful result
>> no matter if P-states are controlled by hardware or firmware
>> and/or if the Linux cpufreq sub-system is or is-not installed.
>>
>> When this routine is invoked more frequently, the measurement
>> interval becomes shorter.  However, the code limits re-computation
>> to 10ms intervals so that average frequency remains meaningful.
>>
>> Discerning users are encouraged to take advantage of
>> the turbostat(8) utility, which can gracefully handle
>> concurrent measurement intervals of arbitrary length.
>>
>> Signed-off-by: Len Brown <len.brown@intel.com>
>
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
>
> Raphael, please take the whole lot through the cpufreq tree.

I will, thanks!

Rafael

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Thread

[PATCH 0/4 v2] x86,cpufreq: unify APERF/MPERF computation Len Brown <lenb@kernel.org> - 2017-06-24 07:20 +0200
  [PATCH 2/4 v2] x86: use common aperfmperf_khz_on_cpu() to calculate KHz using APERF/MPERF Len Brown <lenb@kernel.org> - 2017-06-24 07:20 +0200
    Re: [PATCH 2/4 v2] x86: use common aperfmperf_khz_on_cpu() to  calculate KHz using APERF/MPERF Thomas Gleixner <tglx@linutronix.de> - 2017-06-24 11:00 +0200
      Re: [PATCH 2/4 v2] x86: use common aperfmperf_khz_on_cpu() to  calculate KHz using APERF/MPERF "Rafael J. Wysocki" <rafael@kernel.org> - 2017-06-24 14:10 +0200
  [PATCH 3/4] intel_pstate: delete scheduler hook in HWP mode Len Brown <lenb@kernel.org> - 2017-06-24 07:20 +0200

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