Re: [PATCH 02/13] cpufreq: Add perf_freq to cpuinfo

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Wed, May 26, 2021 at 9:24 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 03.05.2021 21:27, Jason Andryuk wrote:
> > acpi-cpufreq scales the aperf/mperf measurements by max_freq, but HWP
> > needs to scale by base frequency.  Settings max_freq to base_freq
> > "works" but the code is not obvious, and returning values to userspace
> > is tricky.  Add an additonal perf_freq member which is used for scaling
> > aperf/mperf measurements.
> >
> > Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
> > ---
> > I don't like this, but it seems the best way to re-use the common
> > aperf/mperf code.  The other option would be to add wrappers that then
> > do the acpi vs. hwp scaling.
>
> Not sure I understand what you mean by "wrappers". I would assume that
> for hwp you simply install a different getavg hook? Or else I guess
> I'd need to see at least an outline of what you see as the alternative.

Something like a common get_measured_perf() returning just the
aperf/mperf ratio with cpufreq_driver specific getavg() scaling as
appropriate.

Regards,
Jason