Re: [RFC] Documentation/scheduler/schedutil.txt

From: Quentin Perret
Date: Fri Nov 20 2020 - 04:27:53 EST


On Friday 20 Nov 2020 at 14:49:04 (+0530), Viresh Kumar wrote:
> This is unlikely to be an issue on systems where cpufreq policies are
> shared between multiple CPUs, because in those cases the policy
> utilization is computed as the maximum of the CPU utilization values
> over the whole policy and if that turns out to be low, reducing the
> frequency for the policy most likely is a good idea anyway.

Hmm, I'm not sure I agree with this actually. We may be migrating the
task to a different policy altogether. And even if we migrate to another
CPU in the current policy, the task util_avg may be small just because
it was packed with other tasks on a rq, which means it may not increase
the util of the destination rq by much.

ISTR Douglas' EM-based schedutil boosting series was addressing that at
some point, I'll go have a look back at that discussion...