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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 728C2C4338F for ; Thu, 19 Aug 2021 17:51:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57FDC6108B for ; Thu, 19 Aug 2021 17:51:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234222AbhHSRvm (ORCPT ); Thu, 19 Aug 2021 13:51:42 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:57856 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231909AbhHSRvT (ORCPT ); Thu, 19 Aug 2021 13:51:19 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id D425122148; Thu, 19 Aug 2021 17:50:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1629395441; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qVI72MmhFZvIRWbMKiZkSMNfCWkJTo9zD2YlJdQgd7s=; b=Fv66jqXf+XpUn2cWz5mxhVnE4w8uB1Egn79UNvOotxDBeNpDDi0Fk2xzuZd/pclBm28LOe RgxXjdp9/HHWB200PFMu4gbz/kfFuSPJHVgphvSSTsdk8kiBLf8LWCDz0vRTE2ApbY7mzr FWUTADb6ITK+bE8tO7qzB/Qo5oZuY0o= Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id ACE5013AB1; Thu, 19 Aug 2021 17:50:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id eLSzKfGZHmHnOQAAGKfGzw (envelope-from ); Thu, 19 Aug 2021 17:50:41 +0000 From: =?UTF-8?q?Michal=20Koutn=C3=BD?= To: linux-kernel@vger.kernel.org Cc: Vincent Guittot , Phil Auld , Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Odin Ugedal , Rik van Riel , Giovanni Gherdovich Subject: [RFC PATCH v2 5/5] sched/fair: Simplify ancestor enqueue loops Date: Thu, 19 Aug 2021 19:50:34 +0200 Message-Id: <20210819175034.4577-6-mkoutny@suse.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210819175034.4577-1-mkoutny@suse.com> References: <20210819175034.4577-1-mkoutny@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When a task is enqueued or cfs_rq is unthrottled we have work to do from the cfs_rq in question possibly up to root. The important nodes on the path are throttled cfs_rqs or cfs_rqs already enqueud to their parent. Instead of multiple (interrupted) loops make all work in a single loop and decide what all needs to be done inside it. This undoes parts of commit 39f23ce07b93 ("sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list") but it should not bring any functional changes. Note some PELT stats update code is duplicated both in enqueue_entity and the ancestor loop (update_load_avg, se_update_runnable, update_cfs_group). It'd be nice to factor these out, however, the later parts of enqueue_entity rely on the updates, so stick with the current repetition. Signed-off-by: Michal Koutný --- kernel/sched/fair.c | 57 +++++++++++++++++---------------------------- 1 file changed, 21 insertions(+), 36 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9978485334ec..79f183336fa8 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4883,6 +4883,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); struct sched_entity *se; long task_delta, idle_task_delta; + int enqueue = 1; cfs_rq->throttled = 0; @@ -4911,29 +4912,21 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) task_delta = cfs_rq->h_nr_running; idle_task_delta = cfs_rq->idle_h_nr_running; for_each_sched_entity(se) { - if (se->on_rq) - break; cfs_rq = cfs_rq_of(se); - enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); - - cfs_rq->h_nr_running += task_delta; - cfs_rq->idle_h_nr_running += idle_task_delta; - /* end evaluation on encountering a throttled cfs_rq */ - if (cfs_rq_throttled(cfs_rq)) - goto unthrottle_throttle; - } - - for_each_sched_entity(se) { - cfs_rq = cfs_rq_of(se); - - update_load_avg(cfs_rq, se, UPDATE_TG); - se_update_runnable(se); + if (se->on_rq) + enqueue = 0; + if (enqueue) + enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); + else { + update_load_avg(cfs_rq, se, UPDATE_TG); + se_update_runnable(se); + /* XXX: no update_cfs_group(se); */ + } cfs_rq->h_nr_running += task_delta; cfs_rq->idle_h_nr_running += idle_task_delta; - /* end evaluation on encountering a throttled cfs_rq */ if (cfs_rq_throttled(cfs_rq)) goto unthrottle_throttle; @@ -5537,6 +5530,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) struct sched_entity *se = &p->se; int idle_h_nr_running = task_has_idle_policy(p); int task_new = !(flags & ENQUEUE_WAKEUP); + int enqueue = 1; /* * The code below (indirectly) updates schedutil which looks at @@ -5555,27 +5549,18 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT); for_each_sched_entity(se) { - if (se->on_rq) - break; cfs_rq = cfs_rq_of(se); - enqueue_entity(cfs_rq, se, flags); - cfs_rq->h_nr_running++; - cfs_rq->idle_h_nr_running += idle_h_nr_running; - - /* end evaluation on encountering a throttled cfs_rq */ - if (cfs_rq_throttled(cfs_rq)) - goto enqueue_throttle; - - flags = ENQUEUE_WAKEUP; - } - - for_each_sched_entity(se) { - cfs_rq = cfs_rq_of(se); - - update_load_avg(cfs_rq, se, UPDATE_TG); - se_update_runnable(se); - update_cfs_group(se); + if (se->on_rq) + enqueue = 0; + if (enqueue) { + enqueue_entity(cfs_rq, se, flags); + flags = ENQUEUE_WAKEUP; + } else { + update_load_avg(cfs_rq, se, UPDATE_TG); + se_update_runnable(se); + update_cfs_group(se); + } cfs_rq->h_nr_running++; cfs_rq->idle_h_nr_running += idle_h_nr_running; -- 2.32.0