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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E451C432BE for ; Wed, 28 Jul 2021 07:48:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D64760FA0 for ; Wed, 28 Jul 2021 07:48:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234411AbhG1HsL (ORCPT ); Wed, 28 Jul 2021 03:48:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232691AbhG1HsJ (ORCPT ); Wed, 28 Jul 2021 03:48:09 -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 B06C1C061757; Wed, 28 Jul 2021 00:48:08 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id e2-20020a17090a4a02b029016f3020d867so2983073pjh.3; Wed, 28 Jul 2021 00:48:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=nSOViMYPYa18THue5NB1xRZRfJm692a7CdBC4/LyTC4=; b=KNM2TQ0qBbPb4XvWNcysK8INoORw2FRUtbc8UbVGuaP8PeRKXOA40SbsDF9oCehOVL AnCZvTFY+1SPWB6JTBKcQKVHe3UPQGU3v1GUFjON3h/+SJzOISApHH7sj4rhrF7i2OA/ MoxIDhyejas59nJVOYyl3xM1pLZ6ytfPEfoAhwvPgna4fkebhtY+gUYU+jJCtA+Ctm3k Ji/a68Vrx6gto6KOy8+ipXUFVimMCo4eWMWAltb/IoZ4C2U32jFknB1VnzXzmkX2ohHe CJffsTry3FwO+oIN4xrkKxl/JfuJtPbRpXoMTAJLEmaV29xTQ0CpI2LIj2vNyc5xy9+V XZgQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=nSOViMYPYa18THue5NB1xRZRfJm692a7CdBC4/LyTC4=; b=aNryeBLSB+UUUiT8cNZOdvRfD5SbdGJiFqNL8zRo+0kiiJDagddv76/uoGDKwddmGp 8WMQL2xAsFunVJAN7QVOZD3C1EMXJMly7by+ER+Vfd9T3JZ7aGgmOz5XF7dnjzzM1JVy j7K7k9gIDSY0eHQLiSmvkH3kbl54nFwNkQovtvd6MyLfa93ozz86Q3op9cLHPkXmZqk1 4x911aFgGBvXTWsQmavHULYIO2B5MYDhCK1lV0BpeHEnxy+po4iBk8G13vlpXXa93zvu jb75QY4VD3lRJ1VdI+jhebQ9SRByb1fSmoXCJY2PG3DoZbsvE8lyrxH1rvYe9m+75dvC x56Q== X-Gm-Message-State: AOAM5337Qt1qmGRUDr51ZuQrCsf/nokaeEkPRiFLWGLXukFp+DgIjcwZ G1su/n8JQPk2TWrzPcIUhBI= X-Google-Smtp-Source: ABdhPJyQ5x/nLRycZwhKR5z/hDbd5kNAj62JRoGgdGAZyAI1/V0HjUmqvoghYIyRYo7AvfzFszmIXQ== X-Received: by 2002:a63:a42:: with SMTP id z2mr27192335pgk.245.1627458488040; Wed, 28 Jul 2021 00:48:08 -0700 (PDT) Received: from localhost (udp264798uds.hawaiiantel.net. [72.253.242.87]) by smtp.gmail.com with ESMTPSA id i8sm6639232pfk.18.2021.07.28.00.48.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jul 2021 00:48:07 -0700 (PDT) Sender: Tejun Heo Date: Tue, 27 Jul 2021 21:48:06 -1000 From: Tejun Heo To: brookxu Cc: axboe@kernel.dk, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] blk-throtl: optimize IOPS throttle for large IO scenarios Message-ID: References: <1626416569-30907-1-git-send-email-brookxu.cn@gmail.com> <957ab14d-c4bc-32f0-3f7d-af98832ab955@gmail.com> <34a6f4b5-9055-e519-5693-068f8dcb169c@gmail.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 Wed, Jul 28, 2021 at 10:33:20AM +0800, brookxu wrote: > If we do this, I think we will encounter some problems, as follows: > 1. blk-throttle is now at the top of the IO stack. Changing the position of the throttle hook > will make this mechanism invalid for some devices. > 2. We may also need to add a new hook to handle back-merge, otherwise I think the isolation > effect will be worse in the sequential IO scene. > 3. Since bio has entered the IO stack, if it is suspended and resubmitted by blk-throttle, > then there is an IO stack reentry problem, which I think may cause many small problems. Yeah, you're right. I don't think it's worth rocking the boat with blk-throtl at this point. An extra callback it is then. Thanks. -- tejun