Re: [PATCH v6 09/16] sched/cpufreq: uclamp: Add utilization clamping for RT tasks

From: Patrick Bellasi <patrick.bellasi@arm.com>
To: Quentin Perret <quentin.perret@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-api@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Paul Turner <pjt@google.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
	Joel Fernandes <joelaf@google.com>,
	Steve Muckle <smuckle@google.com>,
	Suren Baghdasaryan <surenb@google.com>
Subject: Re: [PATCH v6 09/16] sched/cpufreq: uclamp: Add utilization clamping for RT tasks
Date: Tue, 22 Jan 2019 12:37:04 +0000	[thread overview]
Message-ID: <20190122123704.6rb3xemvxbp5yfjq@e110439-lin> (raw)
In-Reply-To: <20190122123007.dkavjh73w223pa6y@queper01-lin>

On 22-Jan 12:30, Quentin Perret wrote:
> On Tuesday 15 Jan 2019 at 10:15:06 (+0000), Patrick Bellasi wrote:
> > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> > index 520ee2b785e7..38a05a4f78cc 100644
> > --- a/kernel/sched/cpufreq_schedutil.c
> > +++ b/kernel/sched/cpufreq_schedutil.c
> > @@ -201,9 +201,6 @@ unsigned long schedutil_freq_util(int cpu, unsigned long util_cfs,
> >  	unsigned long dl_util, util, irq;
> >  	struct rq *rq = cpu_rq(cpu);
> >  
> > -	if (type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt))
> > -		return max;
> > -
> >  	/*
> >  	 * Early check to see if IRQ/steal time saturates the CPU, can be
> >  	 * because of inaccuracies in how we track these -- see
> > @@ -219,15 +216,19 @@ unsigned long schedutil_freq_util(int cpu, unsigned long util_cfs,
> >  	 * utilization (PELT windows are synchronized) we can directly add them
> >  	 * to obtain the CPU's actual utilization.
> >  	 *
> > -	 * CFS utilization can be boosted or capped, depending on utilization
> > -	 * clamp constraints requested by currently RUNNABLE tasks.
> > +	 * CFS and RT utilization can be boosted or capped, depending on
> > +	 * utilization clamp constraints requested by currently RUNNABLE
> > +	 * tasks.
> >  	 * When there are no CFS RUNNABLE tasks, clamps are released and
> >  	 * frequency will be gracefully reduced with the utilization decay.
> >  	 */
> > -	util = (type == ENERGY_UTIL)
> > -		? util_cfs
> > -		: uclamp_util(rq, util_cfs);
> > -	util += cpu_util_rt(rq);
> > +	util = cpu_util_rt(rq);
> > +	if (type == FREQUENCY_UTIL) {
> > +		util += cpu_util_cfs(rq);
> > +		util  = uclamp_util(rq, util);
> 
> So with this we don't go to max to anymore for CONFIG_UCLAMP_TASK=n no ?

Mmm... good point!

I need to guard this chagen for the !CONFIG_UCLAMP_TASK case!

> 
> Thanks,
> Quentin

Cheers Patrick

-- 
#include <best/regards.h>

Patrick Bellasi