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

From: Rafael J. Wysocki
Date: Sat Jun 24 2017 - 08:03:47 EST


On Sat, Jun 24, 2017 at 10:56 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> 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@xxxxxxxxx>
>
> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> Raphael, please take the whole lot through the cpufreq tree.

I will, thanks!

Rafael