[Bug 215800] amd-pstate does not allow to set arbitrary maximum CPU frequency above 2200MHz for a desktop Zen 3 CPU

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=215800

--- Comment #31 from Artem S. Tashkinov (aros@gmx.com) ---
Created attachment 304797
  --> https://bugzilla.kernel.org/attachment.cgi?id=304797&action=edit
Power Options Processor Power Management in Windows.png

(In reply to Mario Limonciello (AMD) from comment #30)
> > It's a little bit confusing though, as in Windows I can perfectly set
> minimum
> > and maximum CPU frequencies and I totally expected this driver to actually
> > allow that.
> 
> I suppose I'm confused as well.  Windows should be using EPP as well, and
> various software constructs like the power slider will be changing that bias.
> 
> Maybe you can better explain exactly what you do in Windows and exactly what
> is happening.

In Windows I'm free to set minimum and maximum CPU clock speeds to my liking.

Why is it necessary?

1) For instance you want to do benchmarking at certain clock speeds which are
not known to be hitting TDP/TTP/temperature limits, thus they show the true
potential of your CPU.

2) For instance you want to make you CPU run cooler with a very precise
control.

> 
> > Lastly the documentation mentions:
> energy_performance_available_preferences,
> > the file that I don't have.
> 
> Eh?  Didn't your above comment show this:
> 
> /sys/devices/system/cpu/cpufreq/policy0 $ grep -r . 
> energy_performance_available_preferences:default performance
> balance_performance balance_power power 
> 
> > Lastly there's no boost configuration support which is available both for
> > acpi-cpufreq and Intel's native CPPC driver.
> 
> Something seems quite wrong if you're not getting boost support.
> It registers for boost, see
> https://github.com/torvalds/linux/blob/v6.4/drivers/cpufreq/amd-pstate.
> c#L1121

Will recheck in 6.4.x soon.

> 
> > It's worse than acpi-cpufreq from seemingly any PoV. Maybe there are some
> > advantages for APUs but on my desktop I only see major disadvantages
> 
> I /suspect/ what you'll want to do is change the scaling_governor from
> 'powersave' to 'performance' for your desktop use case.

These two options are very coarse vs. being simply able to set maximum clock
speeds.

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