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,URIBL_BLOCKED,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 23E0EC3A5A3 for ; Tue, 27 Aug 2019 11:51:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0020C2173E for ; Tue, 27 Aug 2019 11:51:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726537AbfH0LvZ (ORCPT ); Tue, 27 Aug 2019 07:51:25 -0400 Received: from mail104.syd.optusnet.com.au ([211.29.132.246]:55970 "EHLO mail104.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726071AbfH0LvZ (ORCPT ); Tue, 27 Aug 2019 07:51:25 -0400 Received: from dread.disaster.area (pa49-181-255-194.pa.nsw.optusnet.com.au [49.181.255.194]) by mail104.syd.optusnet.com.au (Postfix) with ESMTPS id F351A43E197; Tue, 27 Aug 2019 21:51:20 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92) (envelope-from ) id 1i2a0M-0005M0-Qf; Tue, 27 Aug 2019 21:51:18 +1000 Date: Tue, 27 Aug 2019 21:51:18 +1000 From: Dave Chinner To: Joseph Qi Cc: Theodore Ts'o , Andreas Dilger , Jan Kara , linux-ext4@vger.kernel.org Subject: Re: [PATCH 0/3] Revert parallel dio reads Message-ID: <20190827115118.GY7777@dread.disaster.area> References: <1566871552-60946-1-git-send-email-joseph.qi@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1566871552-60946-1-git-send-email-joseph.qi@linux.alibaba.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=D+Q3ErZj c=1 sm=1 tr=0 a=YO9NNpcXwc8z/SaoS+iAiA==:117 a=YO9NNpcXwc8z/SaoS+iAiA==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=FmdZ9Uzk2mMA:10 a=VwQbUJbxAAAA:8 a=rNOIIekrAAAA:8 a=7-415B0cAAAA:8 a=i-Dg2M7HJCqoGRThW54A:9 a=CjuIK1q_8ugA:10 a=AjGcO6oz07-iQ99wixmX:22 a=HyV29BWo3XPGBPza7_5j:22 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Tue, Aug 27, 2019 at 10:05:49AM +0800, Joseph Qi wrote: > This patch set is trying to revert parallel dio reads feature at present > since it causes significant performance regression in mixed random > read/write scenario. > > Joseph Qi (3): > Revert "ext4: remove EXT4_STATE_DIOREAD_LOCK flag" > Revert "ext4: fix off-by-one error when writing back pages before dio > read" > Revert "ext4: Allow parallel DIO reads" > > fs/ext4/ext4.h | 17 +++++++++++++++++ > fs/ext4/extents.c | 19 ++++++++++++++----- > fs/ext4/inode.c | 47 +++++++++++++++++++++++++++++++---------------- > fs/ext4/ioctl.c | 4 ++++ > fs/ext4/move_extent.c | 4 ++++ > fs/ext4/super.c | 12 +++++++----- > 6 files changed, 77 insertions(+), 26 deletions(-) Before doing this, you might want to have a chat and co-ordinate with the folks that are currently trying to port the ext4 direct IO code to use the iomap infrastructure: https://lore.kernel.org/linux-ext4/20190827095221.GA1568@poseidon.bobrowski.net/T/#t That is going to need the shared locking on read and will work just fine with shared locking on write, too (it's the code that XFS uses for direct IO). So it might be best here if you work towards shared locking on the write side rather than just revert the shared locking on the read side.... Cheers, Dave, -- Dave Chinner david@fromorbit.com