Re: [PATCH v6 10/14] sched/cpufreq: Refactor the utilization aggregation method
From: Rafael J. Wysocki
Date: Mon Sep 10 2018 - 06:27:43 EST
On Monday, September 10, 2018 12:07:21 PM CEST Quentin Perret wrote:
> On Monday 10 Sep 2018 at 11:53:58 (+0200), Rafael J. Wysocki wrote:
> > On Monday, August 20, 2018 11:44:16 AM CEST Quentin Perret wrote:
> > > Schedutil aggregates the PELT signals of CFS, RT, DL and IRQ in order
> > > to decide which frequency to request. Energy Aware Scheduling (EAS)
> > > needs to be able to predict those requests to assess the energy impact
> > > of scheduling decisions. However, the PELT signals aggregation is only
> > > done in schedutil for now, hence making it hard to synchronize it with
> > > EAS.
> > >
> > > To address this issue, introduce schedutil_freq_util() to perform the
> > > aforementioned aggregation and make it available to other parts of the
> > > scheduler. Since frequency selection and energy estimation still need
> > > to deal with RT and DL signals slightly differently, schedutil_freq_util()
> > > is called with a different 'type' parameter in those two contexts, and
> > > returns an aggregated utilization signal accordingly.
> > This is complementary to patch [02/14] IMO.
> > schedutil_freq_util() and map_util_freq() introduced by that patch should
> > always be used together as they are two parts of one algorithm in my view.
> I agree.
> > Would it be possible to make that clearer?
> I could squash the two at the beginning of the series in a preparatory
> patch that refactors schedutil for EAS all in one go, with a clear
> mention of what we intend to do (make EAS depend on sugov) in the commit
> Would that work ?
I think so.