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 CD29AC433F5 for ; Tue, 1 Feb 2022 17:20:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241441AbiBARUi (ORCPT ); Tue, 1 Feb 2022 12:20:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229836AbiBARUg (ORCPT ); Tue, 1 Feb 2022 12:20:36 -0500 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2CB1C061714; Tue, 1 Feb 2022 09:20:35 -0800 (PST) Received: by mail-pl1-x62f.google.com with SMTP id j16so15924431plx.4; Tue, 01 Feb 2022 09:20:35 -0800 (PST) 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=P/OM7TjxmbJXWO65CCc5u6gW1j1hf5TT48SuvRQUGM4=; b=Th2pE7IdvVAvL27K0Qf/WfMwKXepCYHz0caGuE/hHj2a/Cnls+2LvQk4pd0hPSsVmc /P6uhuhZiLl+17CpwiopYhBR/qCtJBVssgTbQdYnIISNQERS2GZ14qq/Hg7eUUCaN674 VCwtBPI4DwClaYXcyxJN+XKveP7T7CfMg5ljyW3+GK7dyKLOmA8hFBXrPEcKThr76/Z1 McM98ys2DJwA4II8akyGsTpeN9bHmMtE68PaVABB+oTwu+4yN2ONkyGt3QHviGejnNXf 7GgXGq04oayAGMEjV9a1B4yP0UFh2KbtUdz2IDGrTo7ZtGrKniUuXyFMvj/ITBpXNTId pHiQ== 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=P/OM7TjxmbJXWO65CCc5u6gW1j1hf5TT48SuvRQUGM4=; b=nuphlPTDXdkwSDnUWH6Ss4nCdRdRM01kQ/PnJVhFMY2drww3RLAKnddClVatJzm4ju G+AB6hS2MZulCp70yX3pqVTkVScVvjBg8fDV0DJ26PJYkZD4eu0EAmMjbaWxiP1RB49A +JMPrhUwcXVUFYgEyE+Ip3tLosSnBbwqddRu03TW0yLJkx+10lHPm3afWK3cDdSr76lk YIQgQlIBbENFCkt5wP6KKbbGFaYlm/UPtclylwqpuhJvQ3bnMIvZJTajVd6VErs2qPOj FlvfytpnS7AW+hgBrSGK8qymxDykqjyutbBblDGgSt/e/yyWm8RbygMx4WZjFRvu+Oax Cmbg== X-Gm-Message-State: AOAM530FgnFIe+8gwqdIiSh7X5EdtGuXGy9n309ybF87mfrXei6StaOc s1oZSYfjysQvzR0DjwUgsjQ= X-Google-Smtp-Source: ABdhPJyk13e7IHTfwNVZ5H4BVDaKYyNxLipIUGhMx2bZAPAdIiubCpR1ZgCsi1FvSg/sKK/5ZB7m1A== X-Received: by 2002:a17:90b:3144:: with SMTP id ip4mr3488407pjb.23.1643736035151; Tue, 01 Feb 2022 09:20:35 -0800 (PST) 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 a1sm31598385pgg.18.2022.02.01.09.20.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Feb 2022 09:20:34 -0800 (PST) Sender: Tejun Heo Date: Tue, 1 Feb 2022 07:20:32 -1000 From: Tejun Heo To: "yukuai (C)" Cc: axboe@kernel.dk, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com Subject: Re: [PATCH -next] blk-throttle: enable io throttle for root in cgroup v2 Message-ID: References: <20220114093000.3323470-1-yukuai3@huawei.com> <235b0757-d322-2b6e-3ab6-ecc8c82f8f1e@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <235b0757-d322-2b6e-3ab6-ecc8c82f8f1e@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hello, On Thu, Jan 27, 2022 at 10:36:38AM +0800, yukuai (C) wrote: > In our case, the disk is provided by server, and such disk can be shared > by multipul clients. Thus for the client side, the server is a higher > level parent. > > Theoretically, limit the io from server for each client is feasible, > however, the main reason we don't want to do this is the following > shortcoming: > > client can still send io to server unlimited, we can just limit the > amount of io that can complete from server, which might cause too much > pressure on the server side. I don't quite follow the "send io to server unlimited" part. Doesn't that get limited by available number of requests? ie. if the server throttles, the in-flight requests will take longer to complete which exhausts the available requests and thus slows down the client. That's how it's supposed to work on the local machine too. Thanks. -- tejun