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=-13.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 B07A0C433DF for ; Thu, 30 Jul 2020 13:54:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8270C2074B for ; Thu, 30 Jul 2020 13:54:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MrrjsvcD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728389AbgG3Nyh (ORCPT ); Thu, 30 Jul 2020 09:54:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726794AbgG3Nyf (ORCPT ); Thu, 30 Jul 2020 09:54:35 -0400 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C82BC061574 for ; Thu, 30 Jul 2020 06:54:35 -0700 (PDT) Received: by mail-pj1-x1043.google.com with SMTP id a9so4265617pjd.3 for ; Thu, 30 Jul 2020 06:54:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Tge8OIdcAuImjNZAecVhmu6eMDpyDyeIqIaLKa/p9WI=; b=MrrjsvcDuYwum8bwYmttmdNXOPwfYqaqZysQTAmgNzhGr97eP6mSDfGsE7yYAxxR95 o0YK0Oj71dKbaOkgVd7etX4M/xzTgpzq4j3h/GilTxAr/KzrhP9o23/3vPyPkUASXkf7 ed1a5S9U91jXZSJ2/NJh26AFTh5Bh3J6GAnN/rb/0fCIAjSDsC/ztmvQI/vQmiV4BSkc xiZIFou7wG7lbVQg2XJV5sQbcehBV/12c8r/J/50p6GXo6xPJhRvBS/SSgD27m/RxL8q GyBUtC1lpd4rgliincSyJ0hXLzNSby23DsK/SKFAmkbEpqFNI5K1lahgh3e0rKjkI7pN 3F9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Tge8OIdcAuImjNZAecVhmu6eMDpyDyeIqIaLKa/p9WI=; b=aXkmhkhCktsLoRcMtJUsUaVbMNM3IZytBt/qLE5jurVqsk+IV9cVS77L5V/K0mBQqt L9sO790UX97wjA47EJ5TH36qg+vmFFyGJ7VkHTbXgpq11b647eBUaltbRROWi0Bqlodo 1h7Yc/LXlvKZ7cIC1iLyN53wi1cxGiRyWbrpFnPBWEKhZoEhAT/AnF0g0DTPIJ6Jq/20 8QomU81PNgdzKiRuL3RXuRdORCNxvuSjZOlZ9P1a8sVcr8SIIRvclduHZaPbFuMBBZo5 atnGBaSzeUdaK7sjQaem1pMBHG8Dp4doBhBkjvkqrSogBolbUeK7SXfyg2l/XNCr7M6S VJcQ== X-Gm-Message-State: AOAM530qUOJXRIlbPjiDibcWW0vmCljeMcoDeev9lJY3TFyq6NjF3uci aNuJlUIdx/4PaVVIrXjwDW5cWmEAUQo= X-Google-Smtp-Source: ABdhPJxayk8ENK9zCuGUMgiZ61LJsyc3uHFeJEXTbMbb02XV7Bwvui+l2Nb1JAY4hwLLIMQTJJFO3A== X-Received: by 2002:a63:db18:: with SMTP id e24mr32961497pgg.192.1596117275006; Thu, 30 Jul 2020 06:54:35 -0700 (PDT) Received: from localhost.localdomain ([101.32.41.8]) by smtp.gmail.com with ESMTPSA id p10sm6347113pgn.6.2020.07.30.06.54.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2020 06:54:34 -0700 (PDT) From: Qi Zheng To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de Cc: linux-kernel@vger.kernel.org, Qi Zheng Subject: [PATCH] sched/core: add unlikely in group_has_capacity() Date: Thu, 30 Jul 2020 21:54:23 +0800 Message-Id: <20200730135423.232776-1-arch0.zheng@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 1. The group_has_capacity() function is only called in group_classify(). 2. Before calling the group_has_capacity() function, group_is_overloaded() will first judge the following formula, if it holds, the group_classify() will directly return the group_overloaded. (sgs->group_capacity * imbalance_pct) < (sgs->group_runnable * 100) Therefore, when the group_has_capacity() is called, the probability that the above formalu holds is very small. Hint compilers about that. Signed-off-by: Qi Zheng --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2ba8f230feb9..9074fd5e23b2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8234,8 +8234,8 @@ group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs) if (sgs->sum_nr_running < sgs->group_weight) return true; - if ((sgs->group_capacity * imbalance_pct) < - (sgs->group_runnable * 100)) + if (unlikely((sgs->group_capacity * imbalance_pct) < + (sgs->group_runnable * 100))) return false; if ((sgs->group_capacity * 100) > -- 2.25.1