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 BE56CC35673 for ; Sun, 23 Feb 2020 23:19:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 94FFF20880 for ; Sun, 23 Feb 2020 23:19:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727181AbgBWXTG (ORCPT ); Sun, 23 Feb 2020 18:19:06 -0500 Received: from foss.arm.com ([217.140.110.172]:53936 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727624AbgBWXST (ORCPT ); Sun, 23 Feb 2020 18:18:19 -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 5B05630E; Sun, 23 Feb 2020 15:18:18 -0800 (PST) Received: from [10.43.4.116] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 007193F534; Sun, 23 Feb 2020 15:18:16 -0800 (PST) Subject: Re: [PATCH v2 6/6] sched/rt: Remove unnecessary assignment in inc/dec_rt_migration To: Qais Yousef , Ingo Molnar , Peter Zijlstra , Steven Rostedt , Pavan Kondeti Cc: Juri Lelli , Vincent Guittot , Ben Segall , Mel Gorman , linux-kernel@vger.kernel.org References: <20200223184001.14248-1-qais.yousef@arm.com> <20200223184001.14248-7-qais.yousef@arm.com> From: Dietmar Eggemann Message-ID: Date: Mon, 24 Feb 2020 00:16:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200223184001.14248-7-qais.yousef@arm.com> 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 On 23.02.20 19:40, Qais Yousef wrote: > The statement > > rt_rq = &rq_of_rt_rq(rt_rq)->rt > > Was just dereferencing rt_rq to get a pointer to itself. Which is a NOP. > Remove it. > > Signed-off-by: Qais Yousef > --- > kernel/sched/rt.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index b35e49cdafcc..520e84993fe7 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -343,7 +343,6 @@ static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) > return; > > p = rt_task_of(rt_se); > - rt_rq = &rq_of_rt_rq(rt_rq)->rt; IMHO, this is here to get the root rt_rq from any rt_rq (task_groups). Looks like that e.g rt_nr_total is only maintained on root rt_rq's. Similar to CFS' &rq_of(cfs_rq)->cfs (cfs_rq_util_change()) to get root cfs_rq. Not sure where CONFIG_RT_GROUP_SCHED=y is used but it's part of the rt class implementation. [...]