From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Date: Thu, 22 Oct 2020 12:19:29 +0000 Subject: Re: default cpufreq gov, was: [PATCH] sched/fair: check for idle core Message-Id: <1790766.jaFeG3T87Z@kreacher> List-Id: References: <1603211879-1064-1-git-send-email-Julia.Lawall@inria.fr> <34115486.YmRjPRKJaA@kreacher> <20201022120213.GG2611@hirez.programming.kicks-ass.net> In-Reply-To: <20201022120213.GG2611@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: Viresh Kumar , Julia Lawall , Mel Gorman , Ingo Molnar , kernel-janitors@vger.kernel.org, Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Daniel Bristot de Oliveira , linux-kernel@vger.kernel.org, Valentin Schneider , Gilles Muller , srinivas.pandruvada@linux.intel.com, Linux PM , Len Brown [CC linux-pm and Len] On Thursday, October 22, 2020 2:02:13 PM CEST Peter Zijlstra wrote: > On Thu, Oct 22, 2020 at 01:45:25PM +0200, Rafael J. Wysocki wrote: > > On Thursday, October 22, 2020 12:47:03 PM CEST Viresh Kumar wrote: > > > On 22-10-20, 09:11, Peter Zijlstra wrote: > > > > Well, but we need to do something to force people onto schedutil, > > > > otherwise we'll get more crap like this thread. > > > > > > > > Can we take the choice away? Only let Kconfig select which governors are > > > > available and then set the default ourselves? I mean, the end goal being > > > > to not have selectable governors at all, this seems like a good step > > > > anyway. > > > > > > Just to clarify and complete the point a bit here, the users can still > > > pass the default governor from cmdline using > > > cpufreq.default_governor=, which will take precedence over the one the > > > below code is playing with. And later once the kernel is up, they can > > > still choose a different governor from userspace. > > > > Right. > > > > Also some people simply set "performance" as the default governor and then > > don't touch cpufreq otherwise (the idea is to get everything to the max > > freq right away and stay in that mode forever). This still needs to be > > possible IMO. > > Performance/powersave make sense to keep. > > However I do want to retire ondemand, conservative and also very much > intel_pstate/active mode. I agree in general, but IMO it would not be prudent to do that without making schedutil provide the same level of performance in all of the relevant use cases. > I also have very little sympathy for userspace. That I completely agree with. > We should start by making it hard to use them and eventually just delete > them outright. Right, but see above: IMO step 0 should be to ensure that schedutil is a viable replacement for all users.