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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 14F3CC43331 for ; Tue, 12 Nov 2019 17:42:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8DA1206BB for ; Tue, 12 Nov 2019 17:42:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727063AbfKLRmr (ORCPT ); Tue, 12 Nov 2019 12:42:47 -0500 Received: from foss.arm.com ([217.140.110.172]:38298 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726959AbfKLRmr (ORCPT ); Tue, 12 Nov 2019 12:42:47 -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 0B61A30E; Tue, 12 Nov 2019 09:42:47 -0800 (PST) Received: from [10.1.194.37] (e113632-lin.cambridge.arm.com [10.1.194.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DF9143F534; Tue, 12 Nov 2019 09:42:45 -0800 (PST) Subject: Re: [PATCH] sched/fair: add comments for group_type and balancing at SD_NUMA level To: Vincent Guittot , linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, dietmar.eggemann@arm.com, juri.lelli@redhat.com, rostedt@goodmis.org, mgorman@suse.de Cc: bsegall@google.com References: <1573570243-1903-1-git-send-email-vincent.guittot@linaro.org> From: Valentin Schneider Message-ID: <7325dac4-bb26-9fcb-75bc-15b68d35b62d@arm.com> Date: Tue, 12 Nov 2019 17:42:44 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <1573570243-1903-1-git-send-email-vincent.guittot@linaro.org> 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 Hi Vincent, On 12/11/2019 14:50, Vincent Guittot wrote: > Add comments to describe each state of goup_type and to add some details > about the load balance at NUMA level. > > Signed-off-by: Vincent Guittot Suggestions/nits below. There's a bit of duplication with existing comments (e.g. the nice blob atop sg_imbalanced()), but I think it can't hurt to have the few extra lines you're introducing. --- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index bfdcaf91b325..ec93ebd02352 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6955,28 +6955,26 @@ enum fbq_type { regular, remote, all }; * group. see update_sd_pick_busiest(). */ enum group_type { - /* - * The group has spare capacity that can be used to process more work. - */ + /* The group isn't significantly pressured and can be used to process more work */ group_has_spare = 0, /* * The group is fully used and the tasks don't compete for more CPU - * cycles. Nevetheless, some tasks might wait before running. + * cycles. Nevertheless, some tasks might wait before running. */ group_fully_busy, /* - * One task doesn't fit with CPU's capacity and must be migrated on a - * more powerful CPU. + * (SD_ASYM_CPUCAPACITY only) One task doesn't fit on its CPU's + * capacity and must be migrated to a CPU of higher capacity. */ group_misfit_task, /* - * One local CPU with higher capacity is available and task should be - * migrated on it instead on current CPU. + * (SD_ASYM_PACKING only) One local CPU with higher capacity is + * available and task should be migrated to it. */ group_asym_packing, /* - * The tasks affinity prevents the scheduler to balance the load across - * the system. + * The tasks affinity previously prevented the scheduler from balancing + * load across the system. */ group_imbalanced, /*