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=-15.8 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 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 29BD7C433E0 for ; Thu, 7 Jan 2021 08:28:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1EBF23125 for ; Thu, 7 Jan 2021 08:28:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727116AbhAGI22 (ORCPT ); Thu, 7 Jan 2021 03:28:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726953AbhAGI2Z (ORCPT ); Thu, 7 Jan 2021 03:28:25 -0500 Received: from mail-lf1-x131.google.com (mail-lf1-x131.google.com [IPv6:2a00:1450:4864:20::131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F807C0612FE for ; Thu, 7 Jan 2021 00:27:16 -0800 (PST) Received: by mail-lf1-x131.google.com with SMTP id 23so12646364lfg.10 for ; Thu, 07 Jan 2021 00:27:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=l690XN5TZWtKSPCjHwhvoVvMjHxWHQ7pwZ5Jd08fsFY=; b=dV+Tuusb7E7Yqr7fLGv44TNbCL67UDmlpS/QdSuBQ8OZnaO5qfQpAjNrtsTNsYgXIK 6BrdwNNzofeju+4zhU3IpZnhItc6mWLLZJ1aBZT7I6JGAOLleVHO0tiDhEvIL8iH/oIA p+J3jMzJqfDZFB0jFe1GHJd9HI1eB49C8dkij5A/sEDffnHaHxgptuIC/b18Uba9jWTD Yv/jJfsytp5x3D1JphFPK6KPsD4gStxL+8M9M8xonzxbia2OPFhXTrxxNQ4uEALz+uMu nnhOm01fjolMAoJgQmVQ7E0mPIHSTpVWwC8IqV2E97qygorKcPDCGwu1OOeux6aY5KVu 4S/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=l690XN5TZWtKSPCjHwhvoVvMjHxWHQ7pwZ5Jd08fsFY=; b=jMAmkXy4bMyVcDN5oFpHTIVnCzumqJ7AMrUiEWiRmxYfChyg0Ogm95OvfzP15r50tQ 5q7F8cEisPyGc1mexLqET+9imsytY7Kd6Znu+jOQKflHpSRn+1gIgO68rQDVLUtebDSJ yFSc+WrJxBOLr9OQYQbArW0ZKwWyczBoSr+VkGi7dw8bdb2vHE3tLGBB4gFa614Hy7fB Wg2oXYgssg94QxU8x7BB+4q2Ns0TIko9gjKuSFUl8C0PLDw8YKg58bV3cjsEyZMTsNOu IYcXbttRf68HSgrTQHOkTx/jhVeGwG20piNirotqj/v1Wg6vTK5pu2pGQLsk5ZuVZvXn yD5g== X-Gm-Message-State: AOAM531mXg9mCtG6qsyxc7N/EZKa7um5qvMXP0IRYOLCAFOqmTMX5Fl9 qyhAfzTxPSgd0wca1YJQspisVzLcz2n7+/GIjzk5mA== X-Google-Smtp-Source: ABdhPJws8tIhskSL7AY+UM7Guk7kFAT1zqkcsDQlU1/hgiXcZjKBbjCETB+YXDNsXXJKmq3r0pIqaUyjbGQtp3y9uV0= X-Received: by 2002:a19:2d0a:: with SMTP id k10mr3770872lfj.286.1610008035054; Thu, 07 Jan 2021 00:27:15 -0800 (PST) MIME-Version: 1.0 References: <20210107015726.54362-1-qianjun.kernel@gmail.com> In-Reply-To: <20210107015726.54362-1-qianjun.kernel@gmail.com> From: Vincent Guittot Date: Thu, 7 Jan 2021 09:27:04 +0100 Message-ID: Subject: Re: [PATCH 1/1] sched/fair:Avoid unnecessary assignment to cfs_rq->on_list To: qianjun.kernel@gmail.com Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , linux-kernel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 7 Jan 2021 at 02:57, wrote: > > From: jun qian > > Obviously, cfs_rq->on_list is already equal to 1 when cfs_rq->on_list > is assigned a value of 1, so an else branch is needed to avoid unnecessary > assignment operations. > > Signed-off-by: jun qian > --- > 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 04a3ce20da67..ef6ebd95443d 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -305,8 +305,8 @@ static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) > > if (cfs_rq->on_list) > return rq->tmp_alone_branch == &rq->leaf_cfs_rq_list; if cfs_rq->on_list == 1, list_add_leaf_cfs_rq() returns and will not unnecessary set cfs_rq->on_list so your change is useless but makes the code less readable > - > - cfs_rq->on_list = 1; > + else > + cfs_rq->on_list = 1; > > /* > * Ensure we either appear before our parent (if already > -- > 2.18.2 >