Re: cpufreq: intel_pstate: map utilization into the pstate range

[Julia Lawall]

On Thu, 6 Jan 2022, srinivas pandruvada wrote:

> On Thu, 2022-01-06 at 21:43 +0100, Julia Lawall wrote:
> > > > All the turbostat output and graphs I have sent recently were
> > > > just
> > > > for
> > > > continuous spinning:
> > > >
> > > > for(;;);
> > > >
> > > > Now I am trying running for the percentage of the time
> > > > corresponding
> > > > to
> > > > 10 / P for pstate P (ie 0.5 of the time for pstate 20), and then
> > > > sleeping,
> > > > to see whether one can just add the sleeping power consumption of
> > > > the
> > > > machine to compute the efficiency as Rafael suggested.
> > > >
> > > Before doing comparison try freezing uncore.
> > >
> > > wrmsr -a 0x620 0x0808
> > >
> > > to Freeze uncore at 800MHz. Any other value is fine.
> >
> > Thanks for the suggestion.  What is the impact of this?
> Uncore scales based on its own heuristics based in P-state change and
> works in package scope. So to actually see the effect of P-state change
> on energy you can remove variability of uncore power.

OK, thanks.  I will try both options.

julia