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 0E311C3A59C for ; Fri, 16 Aug 2019 13:23:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E1DCF20578 for ; Fri, 16 Aug 2019 13:23:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727246AbfHPNXk (ORCPT ); Fri, 16 Aug 2019 09:23:40 -0400 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:38217 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727240AbfHPNXh (ORCPT ); Fri, 16 Aug 2019 09:23:37 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07486;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0TZdbDa5_1565961805; Received: from JosephdeMacBook-Pro.local(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0TZdbDa5_1565961805) by smtp.aliyun-inc.com(127.0.0.1); Fri, 16 Aug 2019 21:23:25 +0800 Subject: Re: [RFC] performance regression with "ext4: Allow parallel DIO reads" To: Jan Kara , Joseph Qi Cc: Dave Chinner , Andreas Dilger , Theodore Ts'o , Ext4 Developers List , Xiaoguang Wang , Liu Bo References: <29d50d24-f8e7-5ef4-d4d8-3ea6fb1c6ed3@gmail.com> <6DADA28C-542F-45F6-ADB0-870A81ABED23@dilger.ca> <15112e38-94fe-39d6-a8e2-064ff47187d5@linux.alibaba.com> <20190728225122.GG7777@dread.disaster.area> <960bb915-20cc-26a0-7abc-bfca01aa39c0@gmail.com> <20190815151336.GO14313@quack2.suse.cz> From: Joseph Qi Message-ID: <075fd06f-b0b4-4122-81c6-e49200d5bd17@linux.alibaba.com> Date: Fri, 16 Aug 2019 21:23:24 +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: <20190815151336.GO14313@quack2.suse.cz> 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 Hi Jan, Thanks for your reply. On 19/8/15 23:13, Jan Kara wrote: > On Tue 30-07-19 09:34:39, Joseph Qi wrote: >> On 19/7/29 06:51, Dave Chinner wrote: >>> On Fri, Jul 26, 2019 at 09:12:07AM +0800, Joseph Qi wrote: >>>> >>>> >>>> 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? >>> >>> I suspect that the second part of this set of mods that Jan had >>> planned to do (on the write side to use shared locking as well) >>> did not happen and so the DIO writes are serialising the workload. >>> >> >> Thanks for the inputs, Dave. >> Hi Jan, Could you please confirm this? >> If so, should we revert this commit at present? > > Sorry for getting to you only now. I was on vacation and then catching up > with various stuff. I suppose you are not using dioread_nolock mount > option, are you? Can you check what are your results with that mount > option? > Yes, I've just used default mount options when testing. And it is indeed that there is performance improvement with dioread_nolock after reverting the 3 related commits. I'll do a supplementary test with parallel dio reads as well as dioread_nolock and send out the test result. > I have hard time remembering what I was thinking those couple years back > but I think the plan was to switch to dioread_nolock always but somehow I > didn't finish that and now I forgot where I got stuck because I don't see > any problem with that currently. Do you mean mark dioread_nolock as default? Thanks, Joseph > > Honza >