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

[Quentin Perret]

On Tuesday 11 Dec 2018 at 13:22:41 (+0100), Rafael J. Wysocki wrote:
> On Tue, Dec 11, 2018 at 1:17 PM Quentin Perret <quentin.perret@xxxxxxx> 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@xxxxxxx> 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@xxxxxxxxxxxxxx/
> >
> > 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@xxxxxxxxx>
> 
> to this patch.

Thanks !
Quentin