Re: [PATCH v7 6/9] sched/fair: Add sched group latency support

Qais Yousef
2022-11-05T13:41:45Z

On 11/04/22 14:57, Joel Fernandes wrote:

> > The current use of latency_nice doesn't need to walk the hierarchy
> > because it applies at each scheduling level so the childs
> > automatically follow parents' latency.
>
> Not really, I don't see how that will work that way in the wake up path. The
> wake up path (EAS in particular) does not walk through CPU controller group
> hierarchy from top level, it only cares about cpuset/affinities and the
> "effective" values of tasks.
>
> So when you wake up a task, how will you retrieve the attribute for 'prefer
> idle' in the wakeup path using this patchset? The only way is to aggregate
> the CGroup hierarchy information to get a per-task effective value; say using
> a min function.
>
> If you see uclamp_rq_util_with(), that also is using doing uclamp
> aggregation similarly.
>
> So I think Qais is asking about the aggregation function in the EAS wakeup
> path.

Yes that's what I was trying to say. Thanks for helping to clarify it!

Thanks

--
Qais Yousef