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=-1.4 required=3.0 tests=DATE_IN_PAST_12_24, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 90A24C433EF for ; Sun, 8 Sep 2019 08:52:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7461220678 for ; Sun, 8 Sep 2019 08:52:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727536AbfIHIw1 (ORCPT ); Sun, 8 Sep 2019 04:52:27 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:36715 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727359AbfIHIw1 (ORCPT ); Sun, 8 Sep 2019 04:52:27 -0400 Received: from callcc.thunk.org (110.8.30.213.rev.vodafone.pt [213.30.8.110]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x888qH17025741 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 8 Sep 2019 04:52:19 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 55520420842; Sat, 7 Sep 2019 12:00:04 -0400 (EDT) Date: Sat, 7 Sep 2019 12:00:04 -0400 From: "Theodore Y. Ts'o" To: Xiaoguang Wang Cc: linux-ext4@vger.kernel.org Subject: Re: [PATCH] ext4: disable mount with both dioread_nolock and nodelalloc Message-ID: <20190907160004.GB23683@mit.edu> References: <20190731130600.7867-1-xiaoguang.wang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190731130600.7867-1-xiaoguang.wang@linux.alibaba.com> 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 Wed, Jul 31, 2019 at 09:06:00PM +0800, Xiaoguang Wang wrote: > Mount with both dioread_nolock and nodelalloc will result in huge > performance drop, which indeed is an known issue, so before we fix > this issue, currently we disable this behaviour. Below test reproducer > can reveal this performance drop. Is it really worth it to disable this combination? Nothing goes *wrong* per se; it's just slower than we would like. - Ted