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=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 B1D92C33C8C for ; Tue, 7 Jan 2020 13:41:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 923F820656 for ; Tue, 7 Jan 2020 13:41:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728142AbgAGNlK (ORCPT ); Tue, 7 Jan 2020 08:41:10 -0500 Received: from mx2.suse.de ([195.135.220.15]:55816 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727944AbgAGNlK (ORCPT ); Tue, 7 Jan 2020 08:41:10 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 98B1BB1D6; Tue, 7 Jan 2020 13:41:08 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id DE4351E0B47; Tue, 7 Jan 2020 14:41:06 +0100 (CET) Date: Tue, 7 Jan 2020 14:41:06 +0100 From: Jan Kara To: kernel test robot Cc: Matthew Bobrowski , Theodore Ts'o , Jan Kara , Ritesh Harjani , LKML , Linus Torvalds , lkp@lists.01.org Subject: Re: [ext4] b1b4705d54: filebench.sum_bytes_mb/s -20.2% regression Message-ID: <20200107134106.GD25547@quack2.suse.cz> References: <20191224005915.GW2760@shao2-debian> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191224005915.GW2760@shao2-debian> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue 24-12-19 08:59:15, kernel test robot wrote: > FYI, we noticed a -20.2% regression of filebench.sum_bytes_mb/s due to commit: > > > commit: b1b4705d54abedfd69dcdf42779c521aa1e0fbd3 ("ext4: introduce direct I/O read using iomap infrastructure") > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master > > in testcase: filebench > on test machine: 8 threads Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz with 8G memory > with following parameters: > > disk: 1HDD > fs: ext4 > test: fivestreamreaddirect.f > cpufreq_governor: performance > ucode: 0x27 I was trying to reproduce this but I failed with my test VM. I had SATA SSD as a backing store though so maybe that's what makes a difference. Maybe the new code results in somewhat more seeks because the five threads which compete in submitting sequential IO end up being more interleaved? Honza -- Jan Kara SUSE Labs, CR