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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 424CEC4360C for ; Thu, 10 Oct 2019 14:53:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 26EA2214E0 for ; Thu, 10 Oct 2019 14:53:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726613AbfJJOxZ (ORCPT ); Thu, 10 Oct 2019 10:53:25 -0400 Received: from foss.arm.com ([217.140.110.172]:32836 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726473AbfJJOxY (ORCPT ); Thu, 10 Oct 2019 10:53:24 -0400 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 CD3971000; Thu, 10 Oct 2019 07:53:23 -0700 (PDT) Received: from [192.168.0.9] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B74B23F6C4; Thu, 10 Oct 2019 07:53:21 -0700 (PDT) Subject: Re: [RFC v5 4/6] sched/fair: Tune task wake-up logic to pack small background tasks on fewer cores To: Parth Shah , Vincent Guittot Cc: linux-kernel , "open list:THERMAL" , Peter Zijlstra , Ingo Molnar , Patrick Bellasi , Valentin Schneider , Pavel Machek , Doug Smythies , Quentin Perret , "Rafael J. Wysocki" , Tim Chen , Daniel Lezcano References: <20191007083051.4820-1-parth@linux.ibm.com> <20191007083051.4820-5-parth@linux.ibm.com> <80bb34ec-6358-f4dc-d20d-cde6c9d7e197@linux.ibm.com> <86dc25e4-9f19-627f-9581-d74608b7f20c@linux.ibm.com> <0ee8052e-e7fb-83cb-bf70-3c4855ccca8e@linux.ibm.com> From: Dietmar Eggemann Message-ID: <6a620fc4-daf9-dd02-7a81-3d9364bfe162@arm.com> Date: Thu, 10 Oct 2019 16:53:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <0ee8052e-e7fb-83cb-bf70-3c4855ccca8e@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/10/2019 19:02, Parth Shah wrote: > > > On 10/9/19 7:56 PM, Dietmar Eggemann wrote: >> On 09/10/2019 10:57, Parth Shah wrote: >> >> [...] >> >>>> On 07/10/2019 18:53, Parth Shah wrote: >>>>> >>>>> >>>>> On 10/7/19 5:49 PM, Vincent Guittot wrote: >>>>>> On Mon, 7 Oct 2019 at 10:31, Parth Shah wrote: [...] > ok. so does that mean TurboSched can still do some good in such systems as > well ? > I mean save energy even when rd->overutilized==1 by not waking user > classified bg tasks on idle core. I wouldn't say it is impossible but how likely would it be? The Android runtime already classifies its tasks into groups such as background, foreground, top-app, etc. It uses existing infrastructure like cpusets, taskgroups, util_clamp (or its out-of-tree predecessor schedtune) as well as EAS/Energy Model on asymmetric CPU capacity systems to map them (differently) onto the CPU topology to achieve the best possible performance/energy consumption trade-off. Moreover, Google and Arm are keen getting the concept of 'latency nice' upstream so we can map Android Common Kernel's 'prefer idle' feature into the mainline energy-aware wu path. So I'm afraid the question whether TurboSched could make sense on an Android system can only be answered by people responsible for future Android runtime architecture.