From mboxrd@z Thu Jan 1 00:00:00 1970 From: Quentin Perret Subject: Re: [PATCH] Revert "cpufreq: schedutil: Don't restrict kthread to related_cpus unnecessarily" Date: Tue, 8 May 2018 12:24:25 +0100 Message-ID: <20180508112424.GA463@e108498-lin.cambridge.arm.com> References: <20180508073340.13114-1-dietmar.eggemann@arm.com> <20180508082242.bre6sjfvefhz6xc3@vireshk-i7> <8cf21b1a-ca6e-fed7-43c5-94c66ff5986b@arm.com> <20180508094526.ajyjrwytguhv4xpe@vireshk-i7> <20180508100227.GB3752@e108498-lin.cambridge.arm.com> <20180508103427.w2rq3vz3f66y4cxh@vireshk-i7> <20180508110003.GC3752@e108498-lin.cambridge.arm.com> <20180508111451.rmoi2rk3md6lhbvl@vireshk-i7> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180508111451.rmoi2rk3md6lhbvl@vireshk-i7> Sender: linux-kernel-owner@vger.kernel.org To: Viresh Kumar Cc: Dietmar Eggemann , linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , linux-pm@vger.kernel.org, Pavan Kondeti , "Rafael J . Wysocki" , Juri Lelli , Joel Fernandes , Patrick Bellasi List-Id: linux-pm@vger.kernel.org On Tuesday 08 May 2018 at 16:44:51 (+0530), Viresh Kumar wrote: > On 08-05-18, 12:00, Quentin Perret wrote: > > Right, I see your point. Now, with the current implementation, why should > > we randomly force a CPU to manage the kthread of another ? IIUC deadline > > should assign the kthreads to CPUs depending on the state of the system > > when the task is created. So, from one boot to another, you could > > theoretically end up with varying configurations, and varying power/perf > > numbers. > > Yeah, if it is fixed at boot then there is no good reason to push it > to any other CPU. I agree. > To be fair, I think that DL tasks _can_ migrate, but only in special conditions (hotplug, or if a DL task wakes up when another DL task is running and things like that IIRC) but that probably doesn't matter much for our discussion here. Thanks, Quentin