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=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 2F166C38A2A for ; Fri, 8 May 2020 10:58:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 10C2920A8B for ; Fri, 8 May 2020 10:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726325AbgEHK6l (ORCPT ); Fri, 8 May 2020 06:58:41 -0400 Received: from foss.arm.com ([217.140.110.172]:46518 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726091AbgEHK6l (ORCPT ); Fri, 8 May 2020 06:58:41 -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 D6C3A30E; Fri, 8 May 2020 03:58:40 -0700 (PDT) Received: from [192.168.0.7] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D040A3F71F; Fri, 8 May 2020 03:58:37 -0700 (PDT) Subject: Re: [RFC PATCH v3 2/3] docs: scheduler: Add scheduler overview documentation To: Valentin Schneider , John Mathew Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, corbet@lwn.net, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, tsbogend@alpha.franken.de, lukas.bulwahn@gmail.com, x86@kernel.org, linux-mips@vger.kernel.org, tglx@linutronix.de, mostafa.chamanara@basemark.com, rdunlap@infradead.org, Oleg Tsymbal References: <20200507180553.9993-1-john.mathew@unikie.com> <20200507180553.9993-3-john.mathew@unikie.com> From: Dietmar Eggemann Message-ID: Date: Fri, 8 May 2020 12:58:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 07/05/2020 23:15, Valentin Schneider wrote: > > On 07/05/20 19:05, John Mathew wrote: [...] > It would also be an opportunity to have one place to (at least briefly) > describe what the different sched classes do wrt capacity asymmetry - CFS > does one thing, RT now does one thing (see Qais' work), and DL will > hopefully soon follow (see Dietmar's work). > > I'd be happy to contribute (some of) that, if it can be deemed useful (I > personally think it might). I like the idea. Essentially all the code which is guarded by the 'if (static_branch_unlikely(&sched_asym_cpucapacity)' condition or which sets it during bring-up. * 'Cpu capacity < SCHED_LOAD_SCALE for non-big' CPUs setting during bringup (necessary dt binding, CPUfreq influence) * CFS capacity awareness: * wakeup - select_idle_capacity() (replaced wake_cap() & slow path to cover DynamIQ and classical big.LITTLE) * load_balance - misfit handling * RT & DL capacity awareness * ... & the relation to EAS (Documentation/scheduler/sched-energy.rst) This is what we referred to (at least internally) as CAS (Capacity-Aware Scheduling).