On Mon, 2022-10-24 at 21:18 +0200, Rafael J. Wysocki wrote: > Hi All, > > The HWP calibration in intel_pstate is needed to map HWP performance > levels to > frequencies, which are used in the cpufreq sysfs interface, in a > reliable way. > On all non-hybrid "core" platforms it is sufficient to multiply the > HWP > performance levels by 100000 to obtain the corresponding frequencies, > but on > hybrid ones there is a difference between P-cores and E-cores. > > Previous attempts to make this work were based on using CPPC (and in > particular > the nominal performance values provided by _CPC), but it turns out > that the > CPPC information is not sufficiently reliable for this purpose and > the only > way to do it is to use a hard-coded scaling factors for P-cores and > for E-cores > (which fortunately is the same as in the non-hybrid case). > Fortunately, the > same scaling factor for P-cores works on all of the hybrid platforms > to date. > > The first patch in the series ensures that all of the CPUs will use > correct > information from MSRs by avoiding the situations in which an MSR > values read > on one CPU will be used for performance scaling of another CPU. > > The second one implements the approach outlined above. > > Please see the changelogs for details. Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> Tested-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> > > Thanks! > > >
