From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933936AbdBQMs5 (ORCPT ); Fri, 17 Feb 2017 07:48:57 -0500 Received: from merlin.infradead.org ([205.233.59.134]:51456 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755495AbdBQMs4 (ORCPT ); Fri, 17 Feb 2017 07:48:56 -0500 Date: Fri, 17 Feb 2017 13:48:54 +0100 From: Peter Zijlstra To: "Rafael J. Wysocki" Cc: Viresh Kumar , Ingo Molnar , linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Guittot Subject: Re: [PATCH] cpufreq: schedutil: govern how frequently we change frequency with rate_limit Message-ID: <20170217124854.GD6500@twins.programming.kicks-ass.net> References: <4c9afe0a2cda5016b342f777f244c89c03cdc524.1487178939.git.viresh.kumar@linaro.org> <20170216101210.GD21911@vireshk-i7> <20170216123605.GA6515@twins.programming.kicks-ass.net> <2324492.GOLxZvFDJN@aspire.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2324492.GOLxZvFDJN@aspire.rjw.lan> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 17, 2017 at 01:15:56PM +0100, Rafael J. Wysocki wrote: > On Thursday, February 16, 2017 01:36:05 PM Peter Zijlstra wrote: > > On Thu, Feb 16, 2017 at 03:42:10PM +0530, Viresh Kumar wrote: > > > But when I discussed this with Vincent, he suggested that it may not be required > > > at all as the scheduler (with the helped of "decayed") doesn't call into > > > schedutil too often, i.e. at least 1 ms. And if the CPUs are stable enough (i.e. > > > no interruptions to the running task), we wouldn't reevaluate before the next > > > tick. > > > > There are still the attach/detach callers to cfs_rq_util_change() that > > kick in for fork/exit and migration. > > > > But yes, barring those we shouldn't end up calling it at silly rates. > > OK > > Does this mean that running governor computations every time its callback > is invoked by the scheduler would be fine? I'd say yes right up till the point someone reports a regression ;-)