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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED 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 00D47C4320A for ; Sat, 31 Jul 2021 19:52:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D4DA060EBB for ; Sat, 31 Jul 2021 19:52:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231529AbhGaTwG (ORCPT ); Sat, 31 Jul 2021 15:52:06 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:40554 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229953AbhGaTwF (ORCPT ); Sat, 31 Jul 2021 15:52:05 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: krisman) with ESMTPSA id EFBF01F42E77 From: Gabriel Krisman Bertazi To: Amir Goldstein Cc: 0day robot , LKML , lkp@lists.01.org, ying.huang@intel.com, feng.tang@intel.com, zhengjun.xing@linux.intel.com, Jan Kara , "Darrick J. Wong" , Theodore Tso , Dave Chinner , David Howells , Khazhismel Kumykov , linux-fsdevel , Ext4 , kernel@collabora.com, Mel Gorman , kernel test robot Subject: Re: [fsnotify] 4c40d6efc8: unixbench.score -3.3% regression Organization: Collabora References: <20210720155944.1447086-9-krisman@collabora.com> <20210731063818.GB18773@xsang-OptiPlex-9020> Date: Sat, 31 Jul 2021 15:51:52 -0400 In-Reply-To: (Amir Goldstein's message of "Sat, 31 Jul 2021 12:27:43 +0300") Message-ID: <87lf5mi7mv.fsf@collabora.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Amir Goldstein writes: > On Sat, Jul 31, 2021 at 9:20 AM kernel test robot wrote: >> >> >> >> Greeting, >> >> FYI, we noticed a -3.3% regression of unixbench.score due to commit: >> >> >> commit: 4c40d6efc8b22b88a45c335ffd6d25b55d769f5b ("[PATCH v4 08/16] fsnotify: pass arguments of fsnotify() in struct fsnotify_event_info") >> url: https://github.com/0day-ci/linux/commits/Gabriel-Krisman-Bertazi/File-system-wide-monitoring/20210721-001444 >> base: https://git.kernel.org/cgit/linux/kernel/git/jack/linux-fs.git fsnotify >> >> in testcase: unixbench >> on test machine: 96 threads 2 sockets Intel(R) Xeon(R) CPU @ 2.30GHz with 128G memory >> with following parameters: >> >> runtime: 300s >> nr_task: 1 >> test: pipe >> cpufreq_governor: performance >> ucode: 0x4003006 >> >> test-description: UnixBench is the original BYTE UNIX benchmark suite aims to test performance of Unix-like system. >> test-url: https://github.com/kdlucas/byte-unixbench >> >> In addition to that, the commit also has significant impact on the following tests: >> >> +------------------+-------------------------------------------------------------------------------------+ >> | testcase: change | will-it-scale: will-it-scale.per_thread_ops -1.3% regression | >> | test machine | 192 threads 4 sockets Intel(R) Xeon(R) Platinum 9242 CPU @ 2.30GHz with 192G memory | >> | test parameters | cpufreq_governor=performance | >> | | mode=thread | >> | | nr_task=100% | >> | | test=eventfd1 | >> | | ucode=0x5003006 | >> +------------------+-------------------------------------------------------------------------------------+ >> >> >> If you fix the issue, kindly add following tag >> Reported-by: kernel test robot >> > > Gabriel, > > It looks like my change throws away much of the performance gain for > small IO on pipes without any watches that was achieved by commit > 71d734103edf ("fsnotify: Rearrange fast path to minimise overhead > when there is no watcher"). > > I think the way to fix it is to lift the optimization in __fsnotify() > to the fsnotify_parent() inline wrapper as Mel considered doing > but was not sure it was worth the effort at the time. > > It's not completely trivial. I think it requires setting a flag > MNT_FSNOTIFY_WATCHED when there are watches on the > vfsmount. I will look into it. Amir, Since this patch is a clean up, would you mind if I drop it from my series and base my work on top of mainline? Eventually, we can rebase this patch, when the performance issue is addressed. I ask because I'm about to send a v5 and I'm not sure if I should wait to have this fixed. -- Gabriel Krisman Bertazi