On 25/01/2021 18:30, Vincent Guittot wrote: > On Mon, 25 Jan 2021 at 11:45, Dietmar Eggemann <dietmar.eggem...@arm.com> > wrote: >> >> On 22/01/2021 20:10, Joel Fernandes wrote: >>> Hi Vincent, >>> >>> Thanks for reply. Please see the replies below: >>> >>> On Fri, Jan 22, 2021 at 05:56:22PM +0100, Vincent Guittot wrote: >>>> On Fri, 22 Jan 2021 at 16:46, Joel Fernandes (Google) >>>> <j...@joelfernandes.org> wrote:
[...] >> If I understood you correctly, you want to avoid these frequent calls >> to update_blocked_averages() here to further avoid invoking sched_util >> via update_blocked_averages() -> cpufreq_update_util() (since 'decayed' >> is set) very often in your setup. > > So It's not clear if the problem that joel wants to raise, is about: > - the running time of update_blocked_averages > - the running time of the cpufreq_update_util which is called because > utilization has decayed during the update of blocked load > - the wake up latency because of newly_idle lb Pretty much so. IIRC his interest is driven by the fact that he saw much less activity in newly_idle lb and therefore cpufreq_update_util on a system with the same kernel and userspace but with less CPUs (i.e. also smaller frequency domains) and less cgroups (with blocked load) and started wondering why. I assume that since he understands this environment now much better, he should be able to come up with better test numbers to show if there is a performance issue on his 2+6 DynamIQ system and if yes, where exactly in this code path.
