Re: [PATCH v10 02/15] sched/cpufreq: Prepare schedutil for Energy Aware Scheduling

From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Quentin Perret <quentin.perret@arm.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Chris Redpath <chris.redpath@arm.com>,
	Patrick Bellasi <patrick.bellasi@arm.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Thara Gopinath <thara.gopinath@linaro.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Todd Kjos <tkjos@google.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Steve Muckle <smuckle@google.com>,
	adharmap@codeaurora.org, Saravana Kannan <skannan@codeaurora.org>,
	Pavan Kondeti <pkondeti@codeaurora.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Eduardo Valentin <edubezval@gmail.com>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	currojerez@riseup.net, Javi Merino <javi.merino@kernel.org>
Subject: Re: [PATCH v10 02/15] sched/cpufreq: Prepare schedutil for Energy Aware Scheduling
Date: Tue, 11 Dec 2018 13:22:41 +0100	[thread overview]
Message-ID: <CAJZ5v0hP4iEQAFOA2AzcgVUzWS5FeQpCza4Ly-esw0qkYwqrLw@mail.gmail.com> (raw)
In-Reply-To: <20181211121742.d6ujfyccwn7t63b3@queper01-lin>

On Tue, Dec 11, 2018 at 1:17 PM Quentin Perret <quentin.perret@arm.com> wrote:
>
> Hi Rafael,
>
> On Tuesday 11 Dec 2018 at 13:01:24 (+0100), Rafael J. Wysocki wrote:
> > On Mon, Dec 3, 2018 at 10:56 AM Quentin Perret <quentin.perret@arm.com> wrote:
> >
> > [cut]
> >
> > >  #ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL
> > > +/**
> > > + * enum schedutil_type - CPU utilization type
> > > + * @FREQUENCY_UTIL:    Utilization used to select frequency
> > > + * @ENERGY_UTIL:       Utilization used during energy calculation
> > > + *
> > > + * The utilization signals of all scheduling classes (CFS/RT/DL) and IRQ time
> > > + * need to be aggregated differently depending on the usage made of them. This
> > > + * enum is used within schedutil_freq_util() to differentiate the types of
> > > + * utilization expected by the callers, and adjust the aggregation accordingly.
> > > + */
> > > +enum schedutil_type {
> > > +       FREQUENCY_UTIL,
> > > +       ENERGY_UTIL,
> > > +};
> >
> > Why not to use bool instead of this?  Do you expect to have more than
> > just two values in the future?  If so, what would be the third one?
>
> Indeed, the only reason is that an enum is easier to extend, if need be.
> I think you mentioned some time ago that CPUIdle could be, in principle,
> interested in having access to aggregated utilization signals of CPUs:
>
> https://lore.kernel.org/lkml/CAJZ5v0j=EYnANGAj9bd44eeux1eCfeMtdn9npe5pSAzE8EVKaA@mail.gmail.com/
>
> So yeah, I kept Peter's original enum and went for documenting the type,
> as you suggested on v7 :-)

OK, so please feel free to add

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

to this patch.