hwpstate_intel cpufreq and est.

[Jesper Schmitz Mouridsen]

On 29.04.2021 20.09, Jesper Schmitz Mouridsen wrote:
> Hi list.
>
> I am working on sysutils/libsysstat [1], I have maintained it over the 
> years.
>
> I even have a little testprogram [2]
>
> Recently I  got a new CPU which uses freq_driver: hwpstate_intel.
>
> It seems to me from values from dev.cpu.X.freq that this drivers 
> supports different freq levels per core?
>
> And that the BUG section in man cpufreq stating that
>
> "When multiple CPUs offer frequency control, they cannot be set to
> different levels and must all offer the same frequency settings."
>
> Does not apply to hwpstate_intel? Is this correct. My current code 
> relies on
>
> this same freq on all cores bug.
>
> [1] https://www.freshports.org/sysutils/libsysstat
>
> [2] https://people.freebsd.org/~jsm/libsysstat-test.tar.gz
>
> Thanks
>
> Jesper Schmtiz Mouridsen.
>
I think I found the answer in https://reviews.freebsd.org/D30004:

Users running newer Intel(R) CPUs may find some differences in dynamic 
frequency control when upgrading to FreeBSD 13.0.
A new driver for the Intel(R) Speed Shift(TM) feature set, available on 
certain SKUs, exposes the ability for the hardware to dynamically vary 
the core frequencies, including on a per core basis.

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