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=-4.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no 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 16AD1C433DB for ; Mon, 15 Feb 2021 07:11:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A096764E71 for ; Mon, 15 Feb 2021 07:11:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229934AbhBOHLc (ORCPT ); Mon, 15 Feb 2021 02:11:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229758AbhBOHL2 (ORCPT ); Mon, 15 Feb 2021 02:11:28 -0500 Received: from mail-pl1-x635.google.com (mail-pl1-x635.google.com [IPv6:2607:f8b0:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 07DD8C061574; Sun, 14 Feb 2021 23:10:46 -0800 (PST) Received: by mail-pl1-x635.google.com with SMTP id u11so3181525plg.13; Sun, 14 Feb 2021 23:10:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=kG7o9TXRTb0hxLW0YdJ/y+yccAFjnMWzFB3U1A5mywg=; b=n5uPaAdphFj4QWOsQ7YE0k42JmJVn0KpHhmDasMqYLqOUBk0hvpreMVp2XlINgmS8m D0DhLKdlO3Uyg70oqbZEHBqfrnlS8ZXrjbCmm8mQaC8GQ8V5aIEx91jzJiSd2nCNfpcF PmmFGHsy6EoT/VfaMCh61U/NpED90ecdAvGikCT4XvuRo0Wubm3tUkPLzDelCAFFUkho gBnO9J4oTs+hQD3aHSoc0Vuyzi2JHcX0F8Eaq+ZmFvjhkIzsIlvN2hLsIDMhZgjt3v+A IDIfQWAXMVvJHwQVByHWHp7LeiX2k8Y3ZtnDfrz3Te1YrGL4Tn2Ag1Ss0mJwuuWiSdAV xhMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=kG7o9TXRTb0hxLW0YdJ/y+yccAFjnMWzFB3U1A5mywg=; b=EJlqXkqHAqiC3HnIoA2r6wk2VxPnEqNe8G9VZfwhFXOmpseuWQm9Q7x5QF0TvZNIgB Sdvo/0kM9cU5vZxHJxiEsO7rH8cOebhPLqfi5M1GM69VALJKsLn4qhWQP1gnn2KduRFJ ZIybEER+ff1amW28YDj/6XfZt/5BjHXdaeYrzZprQQvKTKjFq/2ZTfkE9f7zhuiY5RLH 3MU0Lqeb0t/3vmUJ8OOZhARoviC6ZRq3WuVqTUKyzaYPvhcSztI3dcWpN8Z6fasfJqUh fkdVcboUHV6eXfggJzvOOASiYKkFpV3LMJrGvbPM8FPM+mkLLOlPR5qo2tWrH+04n+V7 ZUPw== X-Gm-Message-State: AOAM531mhx0kK64H/EHF9jOon7ZEuFJpH09Lz9nl7S3CGmaNbadAiTSR X984NTyfxGtCLdzTSqC9ono= X-Google-Smtp-Source: ABdhPJwUCe1VPM98AwqzG6U1jkQqxJaLEIGzqICJmJISQUn7jriEXteS7abf5wkCrIv0rdNo2D+LSA== X-Received: by 2002:a17:902:bccc:b029:de:8483:506d with SMTP id o12-20020a170902bcccb02900de8483506dmr13959966pls.53.1613373046565; Sun, 14 Feb 2021 23:10:46 -0800 (PST) Received: from localhost ([103.220.76.197]) by smtp.gmail.com with ESMTPSA id x20sm16191527pfi.115.2021.02.14.23.10.42 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Sun, 14 Feb 2021 23:10:46 -0800 (PST) Date: Mon, 15 Feb 2021 15:10:46 +0800 From: Yue Hu To: Viresh Kumar Cc: Yue Hu , "Rafael J. Wysocki" , "Rafael J. Wysocki" , Rafael Wysocki , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Benjamin Segall , Mel Gorman , Daniel Bristot de Oliveira , Linux PM , Linux Kernel Mailing List , Yue Hu , zhangwen@yulong.com Subject: Re: [PATCH] cpufreq: schedutil: Don't use the limits_changed flag any more Message-ID: <20210215151046.00001894.zbestahu@gmail.com> In-Reply-To: <20210215063008.hsdkrs4bw7wt3wye@vireshk-i7> References: <20210208030723.781-1-zbestahu@gmail.com> <20210214114421.00000550.zbestahu@163.com> <20210215063008.hsdkrs4bw7wt3wye@vireshk-i7> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 15 Feb 2021 12:00:08 +0530 Viresh Kumar wrote: > On 14-02-21, 11:44, Yue Hu wrote: > > On Fri, 12 Feb 2021 17:14:03 +0100 > > "Rafael J. Wysocki" wrote: > > > This may be running in parallel with sugov_update_next_freq() on a > > > different CPU, so the latter may clear need_freq_update right > > > after it has been set here unless I'm overlooking something. > > > > Whether this logic is also happening for limits_changed in > > sugo_should_update_freq() or not? > > It is but it shouldn't have any side effects as we calculate the next > frequency after cleaning the limits_changed flag. Your patch would > have been fine, but it is not anymore because of commit 23a881852f3e > ("cpufreq: schedutil: Don't skip freq update if need_freq_update is > set"). > > It made a considerable change after which your patch adds a bug. With > 23a881852f3e, need_freq_update is updated/cleared after the next > frequency is calculated, while earlier it was cleared before it. And > so even with the race condition taking place, there were no issues. > Okay, clear.