Re: [PATCH v6 04/11] cpufreq/schedutil: use rt utilization tracking

From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Juri Lelli <juri.lelli@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Morten Rasmussen <Morten.Rasmussen@arm.com>,
	viresh kumar <viresh.kumar@linaro.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Patrick Bellasi <patrick.bellasi@arm.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Quentin Perret <quentin.perret@arm.com>,
	Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v6 04/11] cpufreq/schedutil: use rt utilization tracking
Date: Fri, 22 Jun 2018 13:41:38 +0200	[thread overview]
Message-ID: <20180622114138.GK2494@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAKfTPtA=iWQc3RB2dgJf2LT2e0XezLzGKbQNx=w1xYEPFDEsQQ@mail.gmail.com>

On Fri, Jun 22, 2018 at 10:10:32AM +0200, Vincent Guittot wrote:
> On Thu, 21 Jun 2018 at 20:57, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > So this (and the dl etc. equivalents) result in exactly the problems
> > > complained about last time, no?
> > >
> > > What I proposed was something along the lines of:
> > >
> > >       util = 1024 * sg_cpu->util_cfs;
> > >       util /= (1024 - (sg_cpu->util_rt + sg_cpu->util_dl + ...));
> > >
> > >       return min(sg_cpu->max, util + sg_cpu->bw_dl);
> 
> I see that you use sg_cpu->util_dl and sg_cpu->bw_dl in your equation
> above but this patch 04 only adds rt util_avg and the dl util_avg has
> not been added yet.
>  dl util_avg is added in patch 6
> So for this patch, we are only using sg_cpu->bw_dl

Yeah, not the point really.

It is about how we're going to use the (rt,dl,irq etc..) util values,
more than which particular one was introduced here.

I'm just not a big fan of the whole: freq := cfs_util + rt_util thing
(as would be obvious by now). 