From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754695AbdBPMgO (ORCPT ); Thu, 16 Feb 2017 07:36:14 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:38519 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754111AbdBPMgL (ORCPT ); Thu, 16 Feb 2017 07:36:11 -0500 Date: Thu, 16 Feb 2017 13:36:05 +0100 From: Peter Zijlstra To: Viresh Kumar Cc: "Rafael J. Wysocki" , 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: <20170216123605.GA6515@twins.programming.kicks-ass.net> References: <4c9afe0a2cda5016b342f777f244c89c03cdc524.1487178939.git.viresh.kumar@linaro.org> <6429586.HoWBhxDx3r@aspire.rjw.lan> <4960111.i7trI6xaX7@aspire.rjw.lan> <4471954.l6hp2TNC2v@aspire.rjw.lan> <20170216101210.GD21911@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170216101210.GD21911@vireshk-i7> 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 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.