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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D09FE95A67 for ; Sun, 8 Oct 2023 11:10:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344674AbjJHLKJ (ORCPT ); Sun, 8 Oct 2023 07:10:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54034 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230424AbjJHLKH (ORCPT ); Sun, 8 Oct 2023 07:10:07 -0400 Received: from mail-ot1-x32a.google.com (mail-ot1-x32a.google.com [IPv6:2607:f8b0:4864:20::32a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D72ACAC for ; Sun, 8 Oct 2023 04:10:06 -0700 (PDT) Received: by mail-ot1-x32a.google.com with SMTP id 46e09a7af769-6c644a1845cso2474860a34.2 for ; Sun, 08 Oct 2023 04:10:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696763406; x=1697368206; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=q8ktmwwLv+LDOgbjf3ixbqpkxtDCfxzhl8ckG93FgT8=; b=KfnubNV7ZNLEOFXQjQmaMyPUbU76InBnS6EJ7VJe+GftBTfgEPpfiFUiK2vGPsn1OB Z+04POPSXVUYVKc5HdFNQV3fBDFspojB8CN1tLAqpWqhFXLcLEL+jQlm/lZiECsdEj7R aX5893wvYpEWHqL0Dm3iggk+euqoHSFErxhjBgmxMx16P8i4BeY9alRUyoS2qUs5tcwj MQfOxfdhWqh+jDux974L2J/pQJGkFm5HLiMZMBO4b1SHASs9DKf6cvzfWj7aFzHaA8E/ vEwCx8cS/+oAYdtedHGTiPXhCmNMFPH+Ui69Q+mPWcfWG1kFDFtby2S5FyyQEV128chB bNQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696763406; x=1697368206; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=q8ktmwwLv+LDOgbjf3ixbqpkxtDCfxzhl8ckG93FgT8=; b=V46yNKEcCMfD/MnvjOiXS2pGDZoIBw8PrtGkMaxUOXycJSxddft2c2n9u+F7zsYwN3 WLMMLZHfkxIHT08osEAoCnkcZgmpxgoeA2iPTidFR17nmZ9hNkV9WxchsqT+8gq8/boC vI5HO6fnh9Kr6UgWKJb9OFcUR110SH28XTY5Ar+oJ6nLHIViHKipt73CX/iAgXPJo0rp uKporGmGHZJljMO5S9PcbL4PoZF8NCoXcrHfFCswk5vXzQEebx+zyUBjz8HeWWPAm56y KVeXdDaAzVeeBhiXUB4ZOHUfb63dtIx8ut49fHNg90E0dJuvOeSSOg2MSOu06rWH6ic9 B0tw== X-Gm-Message-State: AOJu0YwlVp3UOWi+xw3Wr6SUb1owjPTnnnjTTddiARkrdVi/DwMXEHaw nGtjIrHKZkcxwdi2Epk9pDjDiVOEPWvMQ4F3 X-Google-Smtp-Source: AGHT+IEMKfeuwRPXqjMF1Fl7m25vPcCv5vQkL0D9td2/m/h/cVfUPOnPi1Va6i54s7D8D6tahDLPTw== X-Received: by 2002:a05:6358:91c:b0:134:c8cb:6a00 with SMTP id r28-20020a056358091c00b00134c8cb6a00mr14026767rwi.12.1696763406114; Sun, 08 Oct 2023 04:10:06 -0700 (PDT) Received: from [10.53.28.113] ([143.92.118.24]) by smtp.gmail.com with ESMTPSA id z8-20020a17090a014800b00262eb0d141esm6937105pje.28.2023.10.08.04.10.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 08 Oct 2023 04:10:05 -0700 (PDT) Message-ID: <5dba07eb-88f0-bf84-494e-b979f32ad44d@gmail.com> Date: Sun, 8 Oct 2023 19:10:01 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [PATCH 2/3] delayacct: convert task->delays to a object To: Peter Zijlstra Cc: bsingharora@gmail.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org References: <531ddc82793a39f4c09316d701a4b1170bcad4ab.1696761522.git.chunguang.xu@shopee.com> <20231008105801.GC6320@noisy.programming.kicks-ass.net> From: brookxu In-Reply-To: <20231008105801.GC6320@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2023/10/8 18:58, Peter Zijlstra 写道: > On Sun, Oct 08, 2023 at 06:49:37PM +0800, brookxu.cn wrote: >> From: Chunguang Xu >> >> Since in some scenarios we still want to get the task delayacct >> through taskstats, so commit <0cd7c741f01de> introduces a sysctl to > This is not the canonical way to reference a commit. > >> enable it dynamically. However, since task->delays is allocated >> during fork(), task->delays will not be reallocated when delayacct >> is enabled later. This will make we cannot get the delayacct of old >> tasks, but the new tasks cans. This can easily lead to confusion. >> Therefore, try to workaround this issue by convert task->delays to >> an object. > And grow task_struct for no reason? I think not. > >> diff --git a/include/linux/sched.h b/include/linux/sched.h >> index 77f01ac385f7..5cc78184a31f 100644 >> --- a/include/linux/sched.h >> +++ b/include/linux/sched.h >> @@ -37,6 +37,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> /* task_struct member predeclarations (sorted alphabetically): */ >> @@ -1331,7 +1332,7 @@ struct task_struct { >> struct page_frag task_frag; >> >> #ifdef CONFIG_TASK_DELAY_ACCT >> - struct task_delay_info *delays; >> + struct task_delay_info delays; >> #endif > Yeah, no. Yes, this way will increase about 80 bytes for task_struct, about 0.85% of size of task_struct, I think this just like sched_statistics, so that can better support dynamically enable through sysctl.