On 2019.08.02 02:28 Rafael J. Wysocki wrote: > 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. All governors for the intel_cpufreq (intel_pstate in passive mode) CPU frequency scaling driver are broken with respect to this issue, not just the schedutil governor. My initial escalation had been focused on acpi-cpufreq/schedutil and intel_cpufreq/schedutil, as they were both broken, and both fixed by my initially submitted reversion. What can I say, I missed that other intel_cpufreq governors were also involved. I tested all of them: conservative ondemand userspace powersave performance schedutil Note that no other governor uses resolve_freq(). ... Doug
