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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 BA1FCC76190 for ; Fri, 26 Jul 2019 01:12:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E3D8218B8 for ; Fri, 26 Jul 2019 01:12:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726980AbfGZBML (ORCPT ); Thu, 25 Jul 2019 21:12:11 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:46903 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726920AbfGZBMK (ORCPT ); Thu, 25 Jul 2019 21:12:10 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R931e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0TXo1h7U_1564103527; Received: from JosephdeMacBook-Pro.local(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0TXo1h7U_1564103527) by smtp.aliyun-inc.com(127.0.0.1); Fri, 26 Jul 2019 09:12:07 +0800 Subject: Re: [RFC] performance regression with "ext4: Allow parallel DIO reads" To: Andreas Dilger , Joseph Qi , Theodore Ts'o Cc: Jan Kara , Ext4 Developers List , Xiaoguang Wang , Liu Bo References: <29d50d24-f8e7-5ef4-d4d8-3ea6fb1c6ed3@gmail.com> <6DADA28C-542F-45F6-ADB0-870A81ABED23@dilger.ca> From: Joseph Qi Message-ID: <15112e38-94fe-39d6-a8e2-064ff47187d5@linux.alibaba.com> Date: Fri, 26 Jul 2019 09:12:07 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <6DADA28C-542F-45F6-ADB0-870A81ABED23@dilger.ca> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 19/7/26 05:20, Andreas Dilger wrote: > >> On Jul 23, 2019, at 5:17 AM, Joseph Qi wrote: >> >> Hi Ted & Jan, >> Could you please give your valuable comments? > > It seems like the original patches should be reverted? There is no data >From my test result, yes. I've also tested libaio with iodepth 16, it behaves the same. Here is the test data for libaio 4k randrw: ------------------------------------------------------------------------------------------- w/ parallel dio reads | READ 78313KB/s, 19578, 1698.70us | WRITE 78313KB/s, 19578, 4837.60us ------------------------------------------------------------------------------------------- w/o parallel dio reads| READ 387774KB/s, 96943, 1009.73us | WRITE 387656KB/s，96914, 308.87us ------------------------------------------------------------------------------------------- Since this commit went into upstream long time ago，to be precise, Linux 4.9, I wonder if someone else has also observed this regression, or anything I missed? Thanks, Joseph > in the original commit message that indicates there is an actual performance > improvement from that patch, but there is data here showing it hurts both > read and write performance quite significantly. > > Cheers, Andreas > >> On 19/7/19 17:22, Joseph Qi wrote: >>> Hi Ted & Jan, >>> I've observed an significant performance regression with the following >>> commit in my Intel P3600 NVMe SSD. >>> 16c54688592c ext4: Allow parallel DIO reads >>> >>> From my initial investigation, it may be because of the >>> inode_lock_shared (down_read) consumes more than inode_lock (down_write) >>> in mixed random read write workload. >>> >>> Here is my test result. >>> >>> ioengine=psync >>> direct=1 >>> rw=randrw >>> iodepth=1 >>> numjobs=8 >>> size=20G >>> runtime=600 >>> >>> w/ parallel dio reads : kernel 5.2.0 >>> w/o parallel dio reads: kernel 5.2.0, then revert the following commits: >>> 1d39834fba99 ext4: remove EXT4_STATE_DIOREAD_LOCK flag (related) >>> e5465795cac4 ext4: fix off-by-one error when writing back pages before dio read (related) >>> 16c54688592c ext4: Allow parallel DIO reads >>> >>> bs=4k: >>> ------------------------------------------------------------------------------------------- >>> w/ parallel dio reads | READ 30898KB/s, 7724, 555.00us | WRITE 30875KB/s, 7718, 479.70us >>> ------------------------------------------------------------------------------------------- >>> w/o parallel dio reads| READ 117915KB/s, 29478, 248.18us | WRITE 117854KB/s，29463, 21.91us >>> ------------------------------------------------------------------------------------------- >>> >>> bs=16k: >>> ------------------------------------------------------------------------------------------- >>> w/ parallel dio reads | READ 58961KB/s, 3685, 835.28us | WRITE 58877KB/s, 3679, 1335.98us >>> ------------------------------------------------------------------------------------------- >>> w/o parallel dio reads| READ 218409KB/s, 13650, 554.46us | WRITE 218257KB/s，13641, 29.22us >>> ------------------------------------------------------------------------------------------- >>> >>> bs=64k: >>> ------------------------------------------------------------------------------------------- >>> w/ parallel dio reads | READ 119396KB/s, 1865, 1759.38us | WRITE 119159KB/s, 1861, 2532.26us >>> ------------------------------------------------------------------------------------------- >>> w/o parallel dio reads| READ 422815KB/s, 6606, 1146.05us | WRITE 421619KB/s, 6587, 60.72us >>> ------------------------------------------------------------------------------------------- >>> >>> bs=512k: >>> ------------------------------------------------------------------------------------------- >>> w/ parallel dio reads | READ 392973KB/s, 767, 5046.35us | WRITE 393165KB/s, 767, 5359.86us >>> ------------------------------------------------------------------------------------------- >>> w/o parallel dio reads| READ 590266KB/s, 1152, 4312.01us | WRITE 590554KB/s, 1153, 2606.82us >>> ------------------------------------------------------------------------------------------- >>> >>> bs=1M: >>> ------------------------------------------------------------------------------------------- >>> w/ parallel dio reads | READ 487779KB/s, 476, 8058.55us | WRITE 485592KB/s, 474, 8630.51us >>> ------------------------------------------------------------------------------------------- >>> w/o parallel dio reads| READ 593927KB/s, 580, 7623.63us | WRITE 591265KB/s, 577, 6163.42us >>> ------------------------------------------------------------------------------------------- >>> >>> Thanks, >>> Joseph >>> > > > Cheers, Andreas > > > > >