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 B9E4AC433EF for ; Tue, 29 Mar 2022 15:24:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238498AbiC2P0H (ORCPT ); Tue, 29 Mar 2022 11:26:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238464AbiC2P0H (ORCPT ); Tue, 29 Mar 2022 11:26:07 -0400 Received: from mail-lf1-x131.google.com (mail-lf1-x131.google.com [IPv6:2a00:1450:4864:20::131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DBC027169 for ; Tue, 29 Mar 2022 08:24:20 -0700 (PDT) Received: by mail-lf1-x131.google.com with SMTP id bt26so30884412lfb.3 for ; Tue, 29 Mar 2022 08:24:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=openvz-org.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=7p35TWvl6IRR76g48gZ/FV3yHCrma4H2n4XIVQjHGbU=; b=rc7cqRTm/2czxCTles9/xCK5rpH8y9OSfuqPHW8xmLuVPgNpeGsjgQ7dqeXGBNg+cv nYFWQYGUKYM5ai2wr/2RzDbRLITVEYSqdutPb7uihwgAKjUArY2ntWDcIDSOMJDZ8xRO 11A+qEOflqtV8TQpSEDb2WbRad+IZLGa+UNci4sAj6MSIJdR/fSVvlmVLZNtA4G4zvcu k8FeX4AQMnMFXccQXUyLRMRK4FAWO0q8LxmoHNJXdVh7vusRccFoD/66Y0llJGM+E/Jx lY2QmNCGZkcphOwyUydg3srZZfz+KygQlBwCO/C3Q23XZhIFTTOvKJTGO6RCJdg3nbAr 9uNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=7p35TWvl6IRR76g48gZ/FV3yHCrma4H2n4XIVQjHGbU=; b=P5XSApKZHNqYEapXCVHcUpPsS4L8E/GZFyP4Yd5kVcDfC1fWZ9Hls2Ll3kDxhTD8Ug dN4p9RnjqcbzuTLZ4TTwPPy9CaiXMVATbwa8Lcsz6Ekxu7dl0kWjCIr/HaIcD3QLO8DF RBG7/1GD3jbEfYl7Q3+esEwQcWUxvBC7DMU9igdBZUu0KcpnyIxKiHeepeHWj1+5KQ4u 22k3TXWt4dJnF0ID64wAZXeIrUW3opl5GESIdxghnDGGjS+Vf6YjJFpvdMJ79TbMt8gn hNSfiJnAyYuKt+9O8HfGfQUR3dVO2j5PUDMZA9ABYzlZpJEwG7eJrRy6oT2LqQi9BHZV C0Vw== X-Gm-Message-State: AOAM5335sgJa4S9HrQhv0FYFmV2wgSveZWKhb7JDX77ydsx2CuxVpLtK l50a2WJlLLNizxuVqrjpy6HEQg== X-Google-Smtp-Source: ABdhPJxrgrgQ8/lRgdnygDMTeGxvGw9V2TWV8TndcAF6ht0JArKuArXclzzTgpLQB5WvXqaVSaNUrg== X-Received: by 2002:a05:6512:39c1:b0:448:3d37:2cf0 with SMTP id k1-20020a05651239c100b004483d372cf0mr3128325lfu.273.1648567458347; Tue, 29 Mar 2022 08:24:18 -0700 (PDT) Received: from [192.168.0.120] ([2.92.192.13]) by smtp.gmail.com with ESMTPSA id p8-20020a2ea408000000b00247e5087157sm2037603ljn.101.2022.03.29.08.24.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Mar 2022 08:24:18 -0700 (PDT) Message-ID: <241b972d-5f78-6282-4f67-131a2566d479@openvz.org> Date: Tue, 29 Mar 2022 18:24:17 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [dm-devel] [PATCH 3/4] dm-qcow2: Introduce driver to create block devices over QCOW2 files Content-Language: en-US To: Christoph Hellwig Cc: agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, song@kernel.org, linux-kernel@vger.kernel.org, khorenko@virtuozzo.com, axboe@kernel.dk, linux-block@vger.kernel.org References: <164846619932.251310.3668540533992131988.stgit@pro> <164846631540.251310.2398727490395218229.stgit@pro> From: Kirill Tkhai In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 29.03.2022 16:34, Christoph Hellwig wrote: > On Mon, Mar 28, 2022 at 02:18:35PM +0300, Kirill Tkhai wrote: >> The driver is request based, since this allows to use blk-mq >> merging of request. Driver splits requests itself, and every >> request (i.e., qio) after splitting fits a single cluster. >> (In some cases it is worth to create bigger splits, and this >> is a subject of further optimizations). > > Nak, please don't do that. If you want finer grained processing use > a bio based driver, not a request based one. This is just getting us > into tons of problems. Could you explain what you mean? Why shouldn't I use generic bio merging code, but implementing my own merging? Which problems you point? Generic blk-mq is well tested and lots of people work on its performance. It's not obvious reason I should better implement own realization. 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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 To: Christoph Hellwig References: <164846619932.251310.3668540533992131988.stgit@pro> <164846631540.251310.2398727490395218229.stgit@pro> From: Kirill Tkhai In-Reply-To: X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 X-Mailman-Approved-At: Wed, 30 Mar 2022 06:08:49 +0000 Subject: Re: [dm-devel] [PATCH 3/4] dm-qcow2: Introduce driver to create block devices over QCOW2 files X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: axboe@kernel.dk, snitzer@redhat.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, song@kernel.org, dm-devel@redhat.com, agk@redhat.com, khorenko@virtuozzo.com Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 29.03.2022 16:34, Christoph Hellwig wrote: > On Mon, Mar 28, 2022 at 02:18:35PM +0300, Kirill Tkhai wrote: >> The driver is request based, since this allows to use blk-mq >> merging of request. Driver splits requests itself, and every >> request (i.e., qio) after splitting fits a single cluster. >> (In some cases it is worth to create bigger splits, and this >> is a subject of further optimizations). > > Nak, please don't do that. If you want finer grained processing use > a bio based driver, not a request based one. This is just getting us > into tons of problems. Could you explain what you mean? Why shouldn't I use generic bio merging code, but implementing my own merging? Which problems you point? Generic blk-mq is well tested and lots of people work on its performance. It's not obvious reason I should better implement own realization. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel