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 7FBB7C43334 for ; Fri, 1 Jul 2022 20:15:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231781AbiGAUPt (ORCPT ); Fri, 1 Jul 2022 16:15:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229664AbiGAUPr (ORCPT ); Fri, 1 Jul 2022 16:15:47 -0400 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2439DBE35; Fri, 1 Jul 2022 13:15:47 -0700 (PDT) Received: by mail-pj1-x1034.google.com with SMTP id g16-20020a17090a7d1000b001ea9f820449so7464130pjl.5; Fri, 01 Jul 2022 13:15:47 -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=FKcO/SCOzVEFqjsxTXwwvXLK9141GPhQIT81OrUhUD8=; b=GLj2L+xs0nzM+HVU1wsfkOPJDQ6JWIefMw43krHXTkq/Ez2BSuy1s2nxPvy+dPmt7K Znt15z2omq0hydFdGh9v2Ism2wVYJxpiajCUt6oZ4ktj7yX9U5hiISqfsvrY9tqrZtWE dPZa46JpmGQ2RoUcPDnDhnQfc4aGUYXXGRkLunZx4ktENzcX37VwLgFrxERNffW87PkX dvb3atYQgmpzWFDwwlXtJlxjFC+FG8xipe5cecfpI5CuHVIDIujMmlJrhC95Z9OTTKHX S1+vgjWLUoKkvncK721jLfm25KwmjC+RQXzdOEjDR0/C8fgugv1YXSvvb9m/Aq3bgquC eO1w== 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=FKcO/SCOzVEFqjsxTXwwvXLK9141GPhQIT81OrUhUD8=; b=eto0697RowT+gygG7f8apE470qjQE4V4c6kzgtX0LpUQCjImeqqnOwE+ea3uqU20tk TJ2utG5auiROy+vf5s8j/KgHPB/eVVEwRa/5+XdMvL7HnxtJRpk1Xf22PEzn2hyNaBA6 aNVK7VSH+nLtCRdk9KTp5Zf13kxcFAtv7vKWJnU5oW+hETdOkPTw6pdo297mpyj6lQv1 i6lTf9R90pqkNmTMnq7dML0vZPWylMXo2MJ8NgofO7TuKtsVqfrVmP4OYsD2dLh0i/0h mOtPDMgyXWokVzZXGbqDLZS0iGbef2UIQAt33nKCVxApGURS7RxDQa+zaQYWqA+Oy/Zd XORA== X-Gm-Message-State: AJIora+QEwFc02iPL0EW3uvFq3Oe1HClKYyU9adTzybia0ljAanMyF9S 8rNFLpuiOL+igeOml9xZsxI= X-Google-Smtp-Source: AGRyM1t4vd7G3/usLB/KzZjKx1UCzOw6QfDEyavD0a7fud4+TTeySuVaNJg/ehBVoqOCGE4bWpQjpw== X-Received: by 2002:a17:90b:38c3:b0:1ec:cb07:f216 with SMTP id nn3-20020a17090b38c300b001eccb07f216mr20770862pjb.168.1656706546455; Fri, 01 Jul 2022 13:15:46 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::5:b551]) by smtp.gmail.com with ESMTPSA id 63-20020a621542000000b00525204224afsm16302911pfv.94.2022.07.01.13.15.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 Jul 2022 13:15:45 -0700 (PDT) Sender: Tejun Heo Date: Sat, 2 Jul 2022 05:15:43 +0900 From: Tejun Heo To: Benjamin Segall Cc: Zhang Qiao , mingo@redhat.com, peterz@infradead.org, Juri Lelli , Vincent Guittot , lizefan.x@bytedance.com, hannes@cmpxchg.org, cgroups@vger.kernel.org, lkml , vschneid@redhat.com, dietmar.eggemann@arm.com, bristot@redhat.com, Steven Rostedt , mgorman@suse.de Subject: Re: [Question] The system may be stuck if there is a cpu cgroup cpu.cfs_quato_us is very low Message-ID: References: <5987be34-b527-4ff5-a17d-5f6f0dc94d6d@huawei.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 On Fri, Jul 01, 2022 at 01:08:21PM -0700, Benjamin Segall wrote: > Yes, fixing (kernel) priority inversion due to CFS_BANDWIDTH requires a > serious reworking of how it works, because it would need to dequeue > tasks individually rather than doing the entire cfs_rq at a time (and > would require some effort to avoid pinging every throttling task to get > it into the kernel). Right, I don't have a good idea on evolving the current implementation into something correct. As you pointed out, we need to account along the sched_group tree but conditionally enforce on each thread. Thanks. -- tejun