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=-2.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 2A11CC43387 for ; Fri, 18 Jan 2019 11:01:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4B0E20823 for ; Fri, 18 Jan 2019 11:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547809311; bh=wfEmSh6ZmA8ouDmXFznhlGUcWMBOj4c/maoE3cCx/7M=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=vePK7/xDM52G2raNOh/xY/Vg5vkGEnPUyHpv6zJmw9Ak2gTRLI6jaQH58Ku8PPsBd r1jUD9U7x4c7b8O8b//HUBpXTtmgMQwCSPnq8BpcN8PMMaMdXcRoAsBUvQEvioJV1J +LFvKie33EGuYKkPU1b0Z2nwXnbR7Wi6pl3CK3S8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727212AbfARLBs (ORCPT ); Fri, 18 Jan 2019 06:01:48 -0500 Received: from mail-ot1-f67.google.com ([209.85.210.67]:41978 "EHLO mail-ot1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726302AbfARLBs (ORCPT ); Fri, 18 Jan 2019 06:01:48 -0500 Received: by mail-ot1-f67.google.com with SMTP id u16so13993636otk.8; Fri, 18 Jan 2019 03:01:47 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VruGQ0yLuvyJ67r1NkzxTel8mR0+YWsmvsxwDsD6Svc=; b=tn6gxfedEOFUoW61dMdS2WV6G8oWiQTExZEFTbMkVNzWmQi6m5GVmn5NXt3KDdOs/x N/YjKoWRwWvPKzBazqlPXrYYB9eo4ujdXsGQ6tPAbtn0wnj9J2kmMknzxh/e9Vwehlzp EoHn2ZD4Wn0Us60ICM2Ia9wN80ikmRwAoTK7b7l/02b9Pe4pKTYSdoqSuXWGOEuZaurZ 5OTZDCyKdJgroQuI0/sw1/jW8lRYMUzOlFT68XAkv7MYtB30I8LRfbDvvgia6v/4fFSc il2X+c0YKjp3JCMkXQ/xP3ZNe68EYN4IrW1KY3jyvIljVzsE0OgO2EG2oj+StAmseFVd oQ0g== X-Gm-Message-State: AJcUukeaZ6eKTpaC34OAB8zSYWTeLqijJ9zlOK8ygv94EufpCOAkonfz aULVQbHHXVR60B2DhMGjXj229NZvivm5NxhJvP0= X-Google-Smtp-Source: ALg8bN7KjySdPKA1aruRHnyfRq1NzHUU6jtVi1nd/dT0z6qVDRDmjZhNxyW9a62VOqOeyPY/K6igk6sBHi6mv+Dv1+U= X-Received: by 2002:a9d:5e8c:: with SMTP id f12mr12053581otl.343.1547809306880; Fri, 18 Jan 2019 03:01:46 -0800 (PST) MIME-Version: 1.0 References: <20190110110546.8101-1-quentin.perret@arm.com> <20190110110546.8101-3-quentin.perret@arm.com> <20190117155117.GG14385@localhost.localdomain> <20190118091652.xn6iw52tccwh6vap@queper01-lin> <20190118103359.jqctbopx25h3zvqs@queper01-lin> In-Reply-To: From: "Rafael J. Wysocki" Date: Fri, 18 Jan 2019 12:01:35 +0100 Message-ID: Subject: Re: [PATCH 2/2] sched: Document Energy Aware Scheduling To: Quentin Perret Cc: "Rafael J. Wysocki" , Juri Lelli , Jonathan Corbet , Peter Zijlstra , "Rafael J. Wysocki" , Ingo Molnar , Morten Rasmussen , qais.yousef@arm.com, Patrick Bellasi , Dietmar Eggemann , "open list:DOCUMENTATION" , Linux PM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 18, 2019 at 11:58 AM Rafael J. Wysocki wrote: > > On Fri, Jan 18, 2019 at 11:34 AM Quentin Perret wrote: > > > > Hi Rafael, > > > > On Friday 18 Jan 2019 at 10:57:08 (+0100), Rafael J. Wysocki wrote: > > > On Fri, Jan 18, 2019 at 10:16 AM Quentin Perret wrote: > > > > > > > > Hi Juri, > > > > > > > > On Thursday 17 Jan 2019 at 16:51:17 (+0100), Juri Lelli wrote: > > > > > On 10/01/19 11:05, Quentin Perret wrote: > > > > [...] > > > > > > +The idea behind introducing an EM is to allow the scheduler to evaluate the > > > > > > +implications of its decisions rather than blindly applying energy-saving > > > > > > +techniques that may have positive effects only on some platforms. At the same > > > > > > +time, the EM must be as simple as possible to minimize the scheduler latency > > > > > > +impact. > > > > > > + > > > > > > +In short, EAS changes the way CFS tasks are assigned to CPUs. When it is time > > > > > > > > > > Not sure if we want to remark the fact that EAS is looking at CFS tasks > > > > > only ATM. > > > > > > > > Oh, what's wrong about mentioning it ? I mean, it is a fact ATM ... > > > > > > But it won't hurt to mention that it may cover other scheduling > > > classes in the future. IOW, the scope limit is not fundamental. > > > > Agreed, I can do that. > > > > > > > > +for the scheduler to decide where a task should run (during wake-up), the EM > > > > > > +is used to break the tie between several good CPU candidates and pick the one > > > > > > +that is predicted to yield the best energy consumption without harming the > > > > > > +system's throughput. The predictions made by EAS rely on specific elements of > > > > > > +knowledge about the platform's topology, which include the 'capacity' of CPUs, > > > > > > > > > > Add a reference to DT bindings docs defining 'capacity' (or define it > > > > > somewhere)? > > > > > > > > Right, I can mention this is defined in the next section. But are you > > > > sure about the reference to the DT bindings ? They're arm-specific right ? > > > > Maybe I can give that as an example or something ... > > > > > > Example sounds right. > > > > > > You also can point to the section below from here. > > > > Sounds good. > > > > > Side note: If the doc is in the .rst format (which Peter won't like > > > I'm sure :-)), you can actually use cross-references in it and you get > > > a translation to an HTML doc (hosted at kernel.org) for free and the > > > cross-references become clickable links in that. > > > > Right, I personally don't mind the .rst format, but the existing files > > in Documentation/power/ and Documentation/scheduler/ are good old txt > > files so I just wanted to keep things consistent. > > In fact, Documentation/power/ is under a slow on-going transition to > .rst (due to the benefits mentioned above). > > > I don't mind converting to rst if necessary :-) > > It is not necessary, but maybe worth considering. That said, as this is targeted at Documentation/scheduler/, being consistent with the other material in there is probably more important.