From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juri Lelli Subject: Re: [RFC PATCH v2 1/8] sched/cpufreq_schedutil: make use of DEADLINE utilization signal Date: Tue, 5 Dec 2017 17:40:28 +0100 Message-ID: <20171205164028.GG15085@localhost.localdomain> References: <20171204102325.5110-1-juri.lelli@redhat.com> <20171204102325.5110-2-juri.lelli@redhat.com> <20171205150935.GL31247@e110439-lin> <20171205152424.GC15085@localhost.localdomain> <20171205163409.GN31247@e110439-lin> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20171205163409.GN31247@e110439-lin> Sender: linux-kernel-owner@vger.kernel.org To: Patrick Bellasi Cc: peterz@infradead.org, mingo@redhat.com, rjw@rjwysocki.net, viresh.kumar@linaro.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, tglx@linutronix.de, vincent.guittot@linaro.org, rostedt@goodmis.org, luca.abeni@santannapisa.it, claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it, bristot@redhat.com, mathieu.poirier@linaro.org, tkjos@android.com, joelaf@google.com, morten.rasmussen@arm.com, dietmar.eggemann@arm.com, alessio.balsini@arm.com, Juri Lelli , Ingo Molnar , "Rafael J . Wysocki" List-Id: linux-pm@vger.kernel.org On 05/12/17 16:34, Patrick Bellasi wrote: > On 05-Dec 16:24, Juri Lelli wrote: > > On 05/12/17 15:09, Patrick Bellasi wrote: > > > > + /* > > > > + * Ideally we would like to set util_dl as min/guaranteed freq and > > > > + * util_cfs + util_dl as requested freq. However, cpufreq is not yet > > > > + * ready for such an interface. So, we only do the latter for now. > > > > + */ > > > > > > Maybe I don't completely get the above comment, but to me it is not > > > really required. > > > > > > When you say that "util_dl" should be set to a min/guaranteed freq > > > are you not actually talking about a DL implementation detail? > > > > > > From the cpufreq standpoint instead, we should always set a capacity > > > which can accommodate util_dl + util_cfs. > > > > It's more for platforms which supports such combination of values for > > frequency requests (CPPC like, AFAIU). The idea being that util_dl is > > what the system has to always guarantee, but it could go up to the sum > > if feasible. > > I see, you mean for systems where you can specify both values at the > same time, i.e. > - please give me util_dl... > - ... but if you have more beer, I would like util_dl + util_cfs > > However, I'm not an expert, on those systems can we really set a > minimum guaranteed performance level? This is my current understanding. Never played with such platforms myself. :) Best, - Juri