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 99565C3A59F for ; Thu, 29 Aug 2019 10:59:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6BF5320828 for ; Thu, 29 Aug 2019 10:59:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726985AbfH2K67 (ORCPT ); Thu, 29 Aug 2019 06:58:59 -0400 Received: from mx2.suse.de ([195.135.220.15]:49720 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726379AbfH2K67 (ORCPT ); Thu, 29 Aug 2019 06:58:59 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 9EF81AF43; Thu, 29 Aug 2019 10:58:58 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 1D26B1E3BE6; Thu, 29 Aug 2019 12:58:58 +0200 (CEST) Date: Thu, 29 Aug 2019 12:58:58 +0200 From: Jan Kara To: Dave Chinner Cc: Joseph Qi , Theodore Ts'o , Andreas Dilger , Jan Kara , linux-ext4@vger.kernel.org Subject: Re: [PATCH 0/3] Revert parallel dio reads Message-ID: <20190829105858.GA22939@quack2.suse.cz> References: <1566871552-60946-1-git-send-email-joseph.qi@linux.alibaba.com> <20190827115118.GY7777@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190827115118.GY7777@dread.disaster.area> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Tue 27-08-19 21:51:18, Dave Chinner wrote: > 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.... Yeah, after converting ext4 DIO path to iomap infrastructure, using shared inode lock for all aligned non-extending DIO writes will be easy so I'd prefer if we didn't have to redo the iomap conversion patches due to these reverts. Honza -- Jan Kara SUSE Labs, CR