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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 412FBC433E0 for ; Thu, 28 Jan 2021 18:41:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 06C3A64E06 for ; Thu, 28 Jan 2021 18:41:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231220AbhA1Sl3 (ORCPT ); Thu, 28 Jan 2021 13:41:29 -0500 Received: from foss.arm.com ([217.140.110.172]:37448 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232088AbhA1SfI (ORCPT ); Thu, 28 Jan 2021 13:35:08 -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 188901509; Thu, 28 Jan 2021 10:32:19 -0800 (PST) Received: from e113632-lin.cambridge.arm.com (e113632-lin.cambridge.arm.com [10.1.194.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 9FA0C3F719; Thu, 28 Jan 2021 10:32:17 -0800 (PST) From: Valentin Schneider To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Vincent Guittot , Dietmar Eggemann , Morten Rasmussen , Qais Yousef , Quentin Perret , Pavan Kondeti , Rik van Riel Subject: [PATCH 8/8] sched/fair: Relax task_hot() for misfit tasks Date: Thu, 28 Jan 2021 18:31:41 +0000 Message-Id: <20210128183141.28097-9-valentin.schneider@arm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210128183141.28097-1-valentin.schneider@arm.com> References: <20210128183141.28097-1-valentin.schneider@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Misfit tasks can and will be preempted by the stopper to migrate them over to a higher-capacity CPU. However, when runnable but not current misfit tasks are scanned by the load balancer (i.e. detach_tasks()), the task_hot() ratelimiting logic may prevent us from enqueuing said task onto a higher-capacity CPU. Align detach_tasks() with the active-balance logic and let it pick a cache-hot misfit task when the destination CPU can provide a capacity uplift. Signed-off-by: Valentin Schneider --- kernel/sched/fair.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index cba9f97d9beb..c2351b87824f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7484,6 +7484,17 @@ static int task_hot(struct task_struct *p, struct lb_env *env) if (env->sd->flags & SD_SHARE_CPUCAPACITY) return 0; + /* + * On a (sane) asymmetric CPU capacity system, the increase in compute + * capacity should offset any potential performance hit caused by a + * migration. + */ + if (sd_has_asym_cpucapacity(env->sd) && + env->idle != CPU_NOT_IDLE && + !task_fits_capacity(p, capacity_of(env->src_cpu)) && + cpu_capacity_greater(env->dst_cpu, env->src_cpu)) + return 0; + /* * Buddy candidates are cache hot: */ -- 2.27.0