Re: [PATCH v5 05/10] cpufreq/schedutil: get max utilization

From: Joel Fernandes <joel@joelfernandes.org>
To: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
	peterz@infradead.org, mingo@kernel.org,
	linux-kernel@vger.kernel.org, rjw@rjwysocki.net,
	dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com,
	viresh.kumar@linaro.org, valentin.schneider@arm.com,
	quentin.perret@arm.com, Luca Abeni <luca.abeni@santannapisa.it>,
	Claudio Scordino <claudio@evidence.eu.com>,
	Joel Fernandes <joelaf@google.com>,
	Alessio Balsini <alessio.balsini@santannapisa.it>
Subject: Re: [PATCH v5 05/10] cpufreq/schedutil: get max utilization
Date: Mon, 28 May 2018 22:08:33 -0700	[thread overview]
Message-ID: <20180529050833.GA226378@joelaf.mtv.corp.google.com> (raw)
In-Reply-To: <20180528101234.GA1293@localhost.localdomain>

On Mon, May 28, 2018 at 12:12:34PM +0200, Juri Lelli wrote:
[..] 
> > +
> > +	util = max_t(unsigned long, util, READ_ONCE(rq->avg_dl.util_avg));
> > +
> > +	return util;
> 
> Anyway, just a quick thought. I guess we should experiment with this a
> bit. Now, I don't unfortunately have a Arm platform at hand for testing.
> Claudio, Luca (now Cc-ed), would you be able to fire some tests with
> this change?
> 
> Oh, adding Joel and Alessio as well that experimented with DEADLINE
> lately.

I also feel that for power reasons, dl.util_avg shouldn't drive the OPP
beyond what the running bandwidth is, or atleast do that only if CFS tasks
are running and being preempted as you/Vincent mentioned in one of the
threads.

With our DL experiments, I didn't measure power but got it to a point where
the OPP is scaling correctly based on DL parameters. I think Alessio did
measure power at his setup but I can't recall now. Alessio?

thanks,

 - Joel