Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH v3 1/2] sched/cpufreq: always consider blocked FAIR utilization | Date | Thu, 31 May 2018 12:46:55 +0200 |
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On Wednesday, May 30, 2018 6:50:10 PM CEST Patrick Bellasi wrote: > On 27-May 11:50, Rafael J. Wysocki wrote: > > On Thu, May 24, 2018 at 4:10 PM, Patrick Bellasi > > <patrick.bellasi@arm.com> wrote: > > > Since the refactoring introduced by: > > > > > > commit 8f111bc357aa ("cpufreq/schedutil: Rewrite CPUFREQ_RT support") > > > > > > we aggregate FAIR utilization only if this class has runnable tasks. > > > This was mainly due to avoid the risk to stay on an high frequency just > > > because of the blocked utilization of a CPU not being properly decayed > > > while the CPU was idle. > > > > > > However, since: > > > > > > commit 31e77c93e432 ("sched/fair: Update blocked load when newly idle") > > > > > > the FAIR blocked utilization is properly decayed also for IDLE CPUs. > > > > > > This allows us to use the FAIR blocked utilization as a safe mechanism > > > to gracefully reduce the frequency only if no FAIR tasks show up on a > > > CPU for a reasonable period of time. > > > > > > Moreover, we also reduce the frequency drops of CPUs running periodic > > > tasks which, depending on the task periodicity and the time required > > > for a frequency switch, was increasing the chances to introduce some > > > undesirable performance variations. > > > > > > Reported-by: Vincent Guittot <vincent.guittot@linaro.org> > > > Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com> > > > Acked-by: Viresh Kumar <viresh.kumar@linaro.org> > > > Acked-by: Vincent Guittot <vincent.guittot@linaro.org> > > > Tested-by: Vincent Guittot <vincent.guittot@linaro.org> > > > Cc: Ingo Molnar <mingo@redhat.com> > > > Cc: Peter Zijlstra <peterz@infradead.org> > > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > Cc: Vincent Guittot <vincent.guittot@linaro.org> > > > Cc: Viresh Kumar <viresh.kumar@linaro.org> > > > Cc: Joel Fernandes <joelaf@google.com> > > > Cc: linux-kernel@vger.kernel.org > > > Cc: linux-pm@vger.kernel.org > > > > Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > Or please let me know if you want me to apply this one. > > Hi Rafael, seems this patch has already been applied in tip/sched/core. > However is missing your tag above. :/
That's OK.
I just wanted to let people know my opinion. :-)
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