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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 343CEC433ED for ; Mon, 17 May 2021 10:12:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F0536008E for ; Mon, 17 May 2021 10:12:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229474AbhEQKOK (ORCPT ); Mon, 17 May 2021 06:14:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39030 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236283AbhEQKOJ (ORCPT ); Mon, 17 May 2021 06:14:09 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EABA7C061573; Mon, 17 May 2021 03:12:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=lYg8w1yLBmodofpJzyH7czSJX3G8qcn/lUBXozlYfmo=; b=UQ8Es1NICSGIPUCaydyjMWO/ez xXqF4mZPQUlN9R/l/pPdrdFfwu7LllJDnk3GJnF+98hqDTDKNKzygj1qOmAf+sbK8cBY+uvpEozm2 /wiNqn/EOqowphFeetCPM0tRjg2nma4BQrcJ+KmFnHMh/GsMa0bRXJw7kg5rBhBDLQDM9+cfgnOXh ZVAiquA9NoNkd3JXYwLBSzh9YoOYTc4vLNgpABbqtJzclWJDBoWbOoNL3jufCtnxe0P/EUW5mqMo/ e3KI1jTcvKgxdPbdHGvF1cuKHyXjzi8acqbJcAbrQNnQgYdeRzo4W6Dgs1AYIB2oo+0m/gs0uIj++ N2ycD2LA==; Received: from hch by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1liaDo-00CnMC-Se; Mon, 17 May 2021 10:11:39 +0000 Date: Mon, 17 May 2021 11:11:36 +0100 From: Christoph Hellwig To: Changheun Lee Cc: hch@infradead.org, Johannes.Thumshirn@wdc.com, alex_y_xu@yahoo.ca, asml.silence@gmail.com, axboe@kernel.dk, bgoncalv@redhat.com, bvanassche@acm.org, damien.lemoal@wdc.com, gregkh@linuxfoundation.org, jaegeuk@kernel.org, jisoo2146.oh@samsung.com, junho89.kim@samsung.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ming.lei@redhat.com, mj0123.lee@samsung.com, osandov@fb.com, patchwork-bot@kernel.org, seunghwan.hyun@samsung.com, sookwan7.kim@samsung.com, tj@kernel.org, tom.leiming@gmail.com, woosung2.lee@samsung.com, yi.zhang@redhat.com, yt0928.kim@samsung.com Subject: Re: [PATCH v10 0/1] bio: limit bio max size Message-ID: References: <20210514063241.22260-1-nanich.lee@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210514063241.22260-1-nanich.lee@samsung.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, May 14, 2021 at 03:32:41PM +0900, Changheun Lee wrote: > I tested 512MB file read with direct I/O. and chunk size is 64MB. > - on SCSI disk, with no limit of bio max size(4GB) : avg. 630 MB/s > - on SCSI disk, with limit bio max size to 1MB : avg. 645 MB/s > - on ramdisk, with no limit of bio max size(4GB) : avg. 2749 MB/s > - on ramdisk, with limit bio max size to 1MB : avg. 3068 MB/s > > I set ramdisk environment as below. > - dd if=/dev/zero of=/mnt/ramdisk.img bs=$((1024*1024)) count=1024 > - mkfs.ext4 /mnt/ramdisk.img > - mkdir /mnt/ext4ramdisk > - mount -o loop /mnt/ramdisk.img /mnt/ext4ramdisk > > With low performance disk, bio submit delay caused by large bio size is > not big protion. So it can't be feel easily. But it will be shown in high > performance disk. So let's attack the problem properly: 1) switch f2fs to a direct I/O implementation that does not suck 2) look into optimizing the iomap code to e.g. submit the bio once it is larger than queue_io_opt() without failing to add to a bio which would be annoying for things like huge pages.