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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BA42C433EF for ; Mon, 25 Oct 2021 17:27:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2327D60EDF for ; Mon, 25 Oct 2021 17:27:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233889AbhJYR3c (ORCPT ); Mon, 25 Oct 2021 13:29:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233414AbhJYR30 (ORCPT ); Mon, 25 Oct 2021 13:29:26 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 734E1C061220; Mon, 25 Oct 2021 10:27:04 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id u6-20020a17090a3fc600b001a00250584aso12007095pjm.4; Mon, 25 Oct 2021 10:27:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=aCZMd4lnZUOWP3HuMJZrRTDzuvD7CVVCcTZfYmmmVYQ=; b=jB5xsxczN9t/FAMcQj8CtRTnmhHtZXcl5SVodMk6K4L0F+P8ivxWvi/7AOYRNNw2c5 KgPQbGuOcYNZKx1m7ZpDeJVGp9IyLAFuM1H1CS7mMqU+ISDG24Qh2p6Eob0J9QViMiM4 u9ctfqMNOaSDV55qSmdjPIGyT64q4bwDb4sA/bO1X/PUCNARks1jSVYH+BdU1XvlLLjF g/hIj+1qJQAWhQ72vovkRU8MFKxf0eTuqGdobXFdu51L2ZK1vyfZA/GQti8M8RJwq6DV 9TzFRGA8MWJ0er52eshkuUVcHxxcwY7IHlTAZOqrkJrskNDDBpzTj2Cr2VGyPEXE9fwZ 37Tg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=aCZMd4lnZUOWP3HuMJZrRTDzuvD7CVVCcTZfYmmmVYQ=; b=cOx3f95/gJ7dgV9empV725HxLC929SZyB+l92T32KPWe05lreQmy1KGcQbxNwsVADt yxVV9LA0WN0SzRw1582Z5iixJsH5x5mCtnefg6RRIbxiQBWAToWYgK8QPuLItsGuvRuK 8FdT/xGUNGTyDdjmxlYUspBz/bDmfX22SbLctrkBCLAaO+nqr11rV+Xprh9wqX5iGmkp rwwOpl6cZWuL7OWVtUdbdQVGgYYogvGYIJ+mXdz4+6RduqhT//gELevLk/8OHIy6jv41 Pm6OeNR0DCYPLs3D2jFCBl71NL8bOvHcDpTeI3SUAC29MfGK8FuTHXEua8DRpJLF/on+ //0w== X-Gm-Message-State: AOAM531hr16zM58RX01D+L7gi9F+7VwBtMs5PyRgZJBpouyRmPLpZa7V Y4vETOOlMz7RrcbqodItBBwCajVwvzWhUQ== X-Google-Smtp-Source: ABdhPJwmiPVKv0R8Ef+ST6u2Ao5/iO3yRxb9hxL+s6APNWSvdah+WdOyk2J8yvuVFayQk7ILd/IxOg== X-Received: by 2002:a17:902:aa82:b0:140:4655:b211 with SMTP id d2-20020a170902aa8200b001404655b211mr9918872plr.38.1635182823755; Mon, 25 Oct 2021 10:27:03 -0700 (PDT) Received: from localhost (2603-800c-1a02-1bae-e24f-43ff-fee6-449f.res6.spectrum.com. [2603:800c:1a02:1bae:e24f:43ff:fee6:449f]) by smtp.gmail.com with ESMTPSA id d13sm21078439pfu.196.2021.10.25.10.27.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Oct 2021 10:27:03 -0700 (PDT) Sender: Tejun Heo Date: Mon, 25 Oct 2021 07:27:02 -1000 From: Tejun Heo To: Shakeel Butt Cc: Michal =?iso-8859-1?Q?Koutn=FD?= , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] cgroup: no need for cgroup_mutex for /proc/cgroups Message-ID: References: <20211025061916.3853623-1-shakeelb@google.com> <20211025061916.3853623-3-shakeelb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211025061916.3853623-3-shakeelb@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 24, 2021 at 11:19:16PM -0700, Shakeel Butt wrote: > On the real systems, the cgroups hierarchies are setup early and just > once by the node controller, so, other than number of cgroups, all > information in /proc/cgroups remain same for the system uptime. Let's > remove the cgroup_mutex usage on reading /proc/cgroups. There is a > chance of inconsistent number of cgroups for co-mounted cgroups while > printing the information from /proc/cgroups but that is not a big > issue. In addition /proc/cgroups is a v1 specific interface, so the > dependency on it should reduce over time. > > The main motivation for removing the cgroup_mutex from /proc/cgroups is > to reduce the avenues of its contention. On our fleet, we have observed > buggy application hammering on /proc/cgroups and drastically slowing > down the node controller on the system which have many negative > consequences on other workloads running on the system. > > Signed-off-by: Shakeel Butt Applied 1-3 to cgroup/for-5.16. Thanks. -- tejun