From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail03.adl2.internode.on.net ([150.101.137.141]:47008 "EHLO ipmail03.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752380AbeFEWiV (ORCPT ); Tue, 5 Jun 2018 18:38:21 -0400 Date: Wed, 6 Jun 2018 08:38:13 +1000 From: Dave Chinner Subject: Re: [lkp-robot] [xfs] b027d4c97b: fio.latency_2ms% +7.1% regression Message-ID: <20180605223813.GI10363@dastard> References: <20180605071657.GP16472@yexl-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180605071657.GP16472@yexl-desktop> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: kernel test robot Cc: Dave Chinner , "Darrick J. Wong" , Christoph Hellwig , Carlos Maiolino , LKML , linux-xfs@vger.kernel.org, lkp@01.org On Tue, Jun 05, 2018 at 03:16:57PM +0800, kernel test robot wrote: > > Greeting, > > FYI, we noticed a +7.1%% regression of fio.latency_2ms% due to commit: > > > commit: b027d4c97b9675c2ad75dec94be4e46dceb3ec74 ("xfs: don't retry xfs_buf_find on XBF_TRYLOCK failure") > https://git.kernel.org/cgit/fs/xfs/xfs-linux.git xfs-4.18-merge .... > 8925a3dc4771004b b027d4c97b9675c2ad75dec94b > ---------------- -------------------------- > %stddev %change %stddev > \ | \ > 46.56 ± 3% +7.1 53.61 fio.latency_2ms% > 8.19 +0.2 8.40 fio.latency_100ms% > 0.74 ± 3% -0.1 0.68 ± 6% fio.latency_250ms% > 25.20 ± 6% -7.3 17.86 ± 6% fio.latency_4ms% > 0.46 ± 9% +0.2 0.69 ± 13% fio.latency_750us% This is not a regression. The number of IOs in the 4ms IO latency bin has reduced by 7%, and inumber in the 2ms IO latency bin has increased by 7%. IOWs, there's a measurable improvement in IO latency as a result of those patches, not a regression. Cheers, Dave. -- Dave Chinner david@fromorbit.com