From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752344AbdBTJ6J (ORCPT ); Mon, 20 Feb 2017 04:58:09 -0500 Received: from mail-pg0-f50.google.com ([74.125.83.50]:33771 "EHLO mail-pg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751357AbdBTJ6H (ORCPT ); Mon, 20 Feb 2017 04:58:07 -0500 Date: Mon, 20 Feb 2017 15:28:03 +0530 From: Viresh Kumar To: "Rafael J. Wysocki" Cc: Peter Zijlstra , 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: <20170220095803.GT21911@vireshk-i7> References: <4c9afe0a2cda5016b342f777f244c89c03cdc524.1487178939.git.viresh.kumar@linaro.org> <20170216101210.GD21911@vireshk-i7> <20170216123605.GA6515@twins.programming.kicks-ass.net> <2324492.GOLxZvFDJN@aspire.rjw.lan> <20170217124854.GD6500@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170217124854.GD6500@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17-02-17, 13:48, Peter Zijlstra wrote: > 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 ;-) @Rafael: Do you want me to send a V2 with the changes you suggested in commit log? -- viresh