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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 B36CBC433E6 for ; Tue, 12 Jan 2021 15:49:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8BF632312F for ; Tue, 12 Jan 2021 15:49:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405659AbhALPsE (ORCPT ); Tue, 12 Jan 2021 10:48:04 -0500 Received: from mx2.suse.de ([195.135.220.15]:36772 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405550AbhALPsD (ORCPT ); Tue, 12 Jan 2021 10:48:03 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id E6FCEAC24; Tue, 12 Jan 2021 15:47:21 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 93EADDA87C; Tue, 12 Jan 2021 16:45:29 +0100 (CET) Date: Tue, 12 Jan 2021 16:45:29 +0100 From: David Sterba To: kernel test robot Cc: Josef Bacik , David Sterba , =?iso-8859-1?Q?Ren=E9?= Rebe , LKML , lkp@lists.01.org, lkp@intel.com, ying.huang@intel.com, feng.tang@intel.com, zhengjun.xing@intel.com, linux-btrfs@vger.kernel.org Subject: Re: [btrfs] e076ab2a2c: fio.write_iops -18.3% regression Message-ID: <20210112154529.GT6430@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, kernel test robot , Josef Bacik , David Sterba , =?iso-8859-1?Q?Ren=E9?= Rebe , LKML , lkp@lists.01.org, lkp@intel.com, ying.huang@intel.com, feng.tang@intel.com, zhengjun.xing@intel.com, linux-btrfs@vger.kernel.org References: <20210112153614.GA2015@xsang-OptiPlex-9020> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210112153614.GA2015@xsang-OptiPlex-9020> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Jan 12, 2021 at 11:36:14PM +0800, kernel test robot wrote: > > Greeting, > > FYI, we noticed a -18.3% regression of fio.write_iops due to commit: > > > commit: e076ab2a2ca70a0270232067cd49f76cd92efe64 ("btrfs: shrink delalloc pages instead of full inodes") > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master > > > in testcase: fio-basic > on test machine: 192 threads Intel(R) Xeon(R) CPU @ 2.20GHz with 192G memory > with following parameters: > > disk: 1SSD > fs: btrfs > runtime: 300s > nr_task: 8 > rw: randwrite > bs: 4k > ioengine: sync > test_size: 256g Though I do a similar test (emulating bit torrent workload), it's a bit extreme as it's 4k synchronous on a huge file. It always takes a lot of time but could point out some concurrency issues namely on faster devices. There are 8 threads possibly competing for the same inode lock or other locks related to it. The mentioned commit fixed another perf regression on a much more common workload (untgrring files), so at this point drop in this fio workload is inevitable.