linux-kernel - Re: [PATCH V4 2/3] sched/core: Rename schedutil_cpu_util() and allow rest of the kernel to use it

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Message-ID: <20201124132239.h3kjk6pdwqeoitvb@vireshk-mac-ubuntu>
Date:   Tue, 24 Nov 2020 18:52:39 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Quentin Perret <qperret@...gle.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org, Lukasz Luba <lukasz.luba@....com>,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH V4 2/3] sched/core: Rename schedutil_cpu_util() and allow
 rest of the kernel to use it

On 24-11-20, 09:10, Quentin Perret wrote:
> Hey Viresh,
> 
> On Tuesday 24 Nov 2020 at 11:56:15 (+0530), Viresh Kumar wrote:
> > There is nothing schedutil specific in schedutil_cpu_util(), rename it
> > to effective_cpu_util(). Also create and expose another wrapper
> > sched_cpu_util() which can be used by other parts of the kernel, like
> > thermal core (that will be done in a later commit).
> > 
> > Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> > ---
> >  include/linux/sched.h            | 21 +++++++++++++++++++++
> >  kernel/sched/core.c              | 11 +++++++++--
> >  kernel/sched/cpufreq_schedutil.c |  2 +-
> >  kernel/sched/fair.c              |  6 +++---
> >  kernel/sched/sched.h             | 19 ++-----------------
> >  5 files changed, 36 insertions(+), 23 deletions(-)
> > 
> > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > index 063cd120b459..926b944dae5e 100644
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -1926,6 +1926,27 @@ extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
> >  #define TASK_SIZE_OF(tsk)	TASK_SIZE
> >  #endif
> >  
> > +#ifdef CONFIG_SMP
> > +/**
> > + * enum cpu_util_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 sched_cpu_util() to differentiate the types of
> > + * utilization expected by the callers, and adjust the aggregation accordingly.
> > + */
> > +enum cpu_util_type {
> > +	FREQUENCY_UTIL,
> > +	ENERGY_UTIL,
> > +};
> > +
> > +/* Returns effective CPU utilization, as seen by the scheduler */
> > +unsigned long sched_cpu_util(int cpu, enum cpu_util_type type,
> > +			     unsigned long max);
> 
> Are 'type' and 'max' useful to anybody outside of kernel/sched ?
> If not then how about we hide them, keep the cpu_util_type enum in
> kernel/sched/sched.h and evaluate arch_scale_cpu_capacity() in
> sched_cpu_util() directly?

cpufreq_cooling uses 'max' (as can be seen in the next patch).

-- 
viresh