From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9572C56201 for ; Fri, 20 Nov 2020 14:38:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65FC722253 for ; Fri, 20 Nov 2020 14:38:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728206AbgKTOiG (ORCPT ); Fri, 20 Nov 2020 09:38:06 -0500 Received: from foss.arm.com ([217.140.110.172]:50090 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727241AbgKTOiG (ORCPT ); Fri, 20 Nov 2020 09:38:06 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6025311D4; Fri, 20 Nov 2020 06:38:05 -0800 (PST) Received: from e123083-lin (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 80AD73F718; Fri, 20 Nov 2020 06:38:03 -0800 (PST) Date: Fri, 20 Nov 2020 15:37:55 +0100 From: Morten Rasmussen To: Peter Zijlstra Cc: "Rafael J. Wysocki" , Ingo Molnar , Thomas Gleixner , Vincent Guittot , dietmar.eggemann@arm.com, patrick.bellasi@matbug.net, lenb@kernel.org, linux-kernel@vger.kernel.org, valentin.schneider@arm.com, ionela.voinescu@arm.com, qperret@google.com, viresh.kumar@linaro.org Subject: Re: [RFC] Documentation/scheduler/schedutil.txt Message-ID: <20201120143715.GA3456@e123083-lin> References: <20201120075527.GB2414@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201120075527.GB2414@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, Looks like a nice summary to me. On Fri, Nov 20, 2020 at 08:55:27AM +0100, Peter Zijlstra wrote: > Hi, > > I was recently asked to explain how schedutil works, the below write-up > is the result of that and I figured we might as well stick it in the > tree. > > Not as a patch for easy reading and commenting. > > --- > > NOTE; all this assumes a linear relation between frequency and work capacity, > we know this is flawed, but it is the best workable approximation. If you replace frequency with performance level everywhere (CPPC style), most of it should still work without that assumption. The assumption might have be made in hw or fw instead though. Morten