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 DC8B6C4332F for ; Tue, 1 Nov 2022 19:15:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230358AbiKATPt (ORCPT ); Tue, 1 Nov 2022 15:15:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230460AbiKATPj (ORCPT ); Tue, 1 Nov 2022 15:15:39 -0400 Received: from mail-pj1-x1030.google.com (mail-pj1-x1030.google.com [IPv6:2607:f8b0:4864:20::1030]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 484801EC59 for ; Tue, 1 Nov 2022 12:15:36 -0700 (PDT) Received: by mail-pj1-x1030.google.com with SMTP id z5-20020a17090a8b8500b00210a3a2364fso2057871pjn.0 for ; Tue, 01 Nov 2022 12:15:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=x7uizm+oURVHURBJUhhwvkQc5dtB/zBCulyqvyF6/Y8=; b=VbWea86l26+5oMoKhy7n5YDJY6whrAOE5UKO7ynw6dFqyspALqzppx/ZjyygQ473MV u4rDukBU9R0eL2HNuBdGV7acEYY2PeYg0WnxkWaahrOIs8lGtFG9PSwpdkrylbwg8hnQ ze0+5XUbJZjzKYxaASQ6mDkM7wcyuS54FByaI40KXHomwMLiiOs8bk6VSfwBpxjfKT6i uQVhdWPe9ZFPsj79oh1tMBnc4fgcOv+D1Tz3BhNy+YHpeUbKoV67S8JXPCB5NSTUWShb QAY3ZZvTksmBuagf0LbG1kgse3Lt8OMW2NF1jaF8oSg6gO7PaV7jKQ+ALv/2vv68E0PA R10g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=x7uizm+oURVHURBJUhhwvkQc5dtB/zBCulyqvyF6/Y8=; b=HfZP4TvnuNhlKXxqi5a4MRDJGOfm7ZOSLkPTWJW9MauHbxR2RoaoJs+zsjTqsJPX/u iT4utCQ2Zus6uoAEzYiWG+cCNDoSBOmN+CyNkE+CRFBfqaXesnmC7fIHz/qHgFFR6kmv eAXKHs375sbNSE444WisTXvsUeibhlkR+mfIamM5UClsJ0Fnd8so/LB+4yfpbcwUJcLl LDv8YEcu3QbJ5oBQcTHOpDUIhwQZ0ttGrNTqatllfuYlhS09af7oT/3NvyVmR/pzdkbx tmQ1EwLrV4rPGJK8La+XKCUdXFfkdMmEoRBFcxqUHj5DkuIufrtl5UUXeKNf1Ura4OQ+ IS1A== X-Gm-Message-State: ACrzQf2TGWPxR+dAuPxClIJuIXuGj5/1PlqwovtPlw/7LbeORsqd6SAY +AvFtT76/8CNKL8X4rCSgFM= X-Google-Smtp-Source: AMsMyM54DpQd/Ccn7cTQvmWnSzabznSFXFhnJHQLMHewIFHnqg2ZEYeiSYy3yrm1hil1Nf+MrtgGqA== X-Received: by 2002:a17:902:ea02:b0:187:2164:89b with SMTP id s2-20020a170902ea0200b001872164089bmr11990656plg.99.1667330135535; Tue, 01 Nov 2022 12:15:35 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::5:f37f]) by smtp.gmail.com with ESMTPSA id t13-20020a170902e1cd00b001754e086eb3sm6699540pla.302.2022.11.01.12.15.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Nov 2022 12:15:35 -0700 (PDT) Sender: Tejun Heo Date: Tue, 1 Nov 2022 09:15:33 -1000 From: Tejun Heo To: Josh Don Cc: Peter Zijlstra , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , linux-kernel@vger.kernel.org, Joel Fernandes Subject: Re: [PATCH v2] sched: async unthrottling for cfs bandwidth Message-ID: References: <20221026224449.214839-1-joshdon@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue, Nov 01, 2022 at 12:11:30PM -0700, Josh Don wrote: > > Just to better understand the situation, can you give some more details on > > the scenarios where cgroup_mutex was in the middle of a shitshow? > > There have been a couple, I think one of the main ones has been writes > to cgroup.procs. cpuset modifications also show up since there's a > mutex there. If you can, I'd really like to learn more about the details. We've had some issues with the threadgroup_rwsem because it's such a big hammer but not necessarily with cgroup_mutex because they are only used in maintenance operations and never from any hot paths. Regarding threadgroup_rwsem, w/ CLONE_INTO_CGROUP (userspace support is still missing unfortunately), the usual worfklow of creating a cgroup, seeding it with a process and then later shutting it down doesn't involve threadgroup_rwsem at all, so most of the problems should go away in the hopefully near future. Thanks. -- tejun