On Friday, August 2, 2019 11:17:55 AM CEST Rafael J. Wysocki wrote: > On Fri, Aug 2, 2019 at 7:44 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: > > > > Intel pstate driver exposes min_perf_pct and max_perf_pct sysfs files, > > which can be used to force a limit on the min/max P state of the driver. > > Though these files eventually control the min/max frequencies that the > > CPUs will run at, they don't make a change to policy->min/max values. > > That's correct. > > > When the values of these files are changed (in passive mode of the > > driver), it leads to calling ->limits() callback of the cpufreq > > governors, like schedutil. On a call to it the governors shall > > forcefully update the frequency to come within the limits. > > OK, so the problem is that it is a bug to invoke the governor's ->limits() > callback without updating policy->min/max, because that's what > "limits" mean to the governors. > > Fair enough. AFAICS this can be addressed by adding PM QoS freq limits requests of each CPU to intel_pstate in the passive mode such that changing min_perf_pct or max_perf_pct will cause these requests to be updated.
