Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751449AbdHJEN5 (ORCPT ); Thu, 10 Aug 2017 00:13:57 -0400 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:42427 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750767AbdHJENz (ORCPT ); Thu, 10 Aug 2017 00:13:55 -0400 X-Original-SENDERIP: 156.147.1.121 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 10.177.220.163 X-Original-MAILFROM: minchan@kernel.org Date: Thu, 10 Aug 2017 13:13:53 +0900 From: Minchan Kim To: Ye Xiaolong Cc: Nadav Amit , "open list:MEMORY MANAGEMENT" , LKML , Andrew Morton , Ingo Molnar , Russell King , Tony Luck , Martin Schwidefsky , "David S. Miller" , Heiko Carstens , Yoshinori Sato , Jeff Dike , linux-arch@vger.kernel.org, lkp@01.org Subject: Re: [lkp-robot] [mm] 7674270022: will-it-scale.per_process_ops -19.3% regression Message-ID: <20170810041353.GB2042@bbox> References: <20170802000818.4760-7-namit@vmware.com> <20170808011923.GE25554@yexl-desktop> <20170808022830.GA28570@bbox> <93CA4B47-95C2-43A2-8E92-B142CAB1DAF7@gmail.com> <970B5DC5-BFC2-461E-AC46-F71B3691D301@gmail.com> <20170808080821.GA31730@bbox> <20170809025902.GA17616@yexl-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170809025902.GA17616@yexl-desktop> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3485 Lines: 75 On Wed, Aug 09, 2017 at 10:59:02AM +0800, Ye Xiaolong wrote: > On 08/08, Minchan Kim wrote: > >On Mon, Aug 07, 2017 at 10:51:00PM -0700, Nadav Amit wrote: > >> Nadav Amit wrote: > >> > >> > Minchan Kim wrote: > >> > > >> >> Hi, > >> >> > >> >> On Tue, Aug 08, 2017 at 09:19:23AM +0800, kernel test robot wrote: > >> >>> Greeting, > >> >>> > >> >>> FYI, we noticed a -19.3% regression of will-it-scale.per_process_ops due to commit: > >> >>> > >> >>> > >> >>> commit: 76742700225cad9df49f05399381ac3f1ec3dc60 ("mm: fix MADV_[FREE|DONTNEED] TLB flush miss problem") > >> >>> url: https://github.com/0day-ci/linux/commits/Nadav-Amit/mm-migrate-prevent-racy-access-to-tlb_flush_pending/20170802-205715 > >> >>> > >> >>> > >> >>> in testcase: will-it-scale > >> >>> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 64G memory > >> >>> with following parameters: > >> >>> > >> >>> nr_task: 16 > >> >>> mode: process > >> >>> test: brk1 > >> >>> cpufreq_governor: performance > >> >>> > >> >>> test-description: Will It Scale takes a testcase and runs it from 1 through to n parallel copies to see if the testcase will scale. It builds both a process and threads based test in order to see any differences between the two. > >> >>> test-url: https://github.com/antonblanchard/will-it-scale > >> >> > >> >> Thanks for the report. > >> >> Could you explain what kinds of workload you are testing? > >> >> > >> >> Does it calls frequently madvise(MADV_DONTNEED) in parallel on multiple > >> >> threads? > >> > > >> > According to the description it is "testcase:brk increase/decrease of one > >> > page”. According to the mode it spawns multiple processes, not threads. > >> > > >> > Since a single page is unmapped each time, and the iTLB-loads increase > >> > dramatically, I would suspect that for some reason a full TLB flush is > >> > caused during do_munmap(). > >> > > >> > If I find some free time, I’ll try to profile the workload - but feel free > >> > to beat me to it. > >> > >> The root-cause appears to be that tlb_finish_mmu() does not call > >> dec_tlb_flush_pending() - as it should. Any chance you can take care of it? > > > >Oops, but with second looking, it seems it's not my fault. ;-) > >https://marc.info/?l=linux-mm&m=150156699114088&w=2 > > > >Anyway, thanks for the pointing out. > >xiaolong.ye, could you retest with this fix? > > > > I've queued tests for 5 times and results show this patch (e8f682574e4 "mm: > decrease tlb flush pending count in tlb_finish_mmu") does help recover the > performance back. > > 378005bdbac0a2ec 76742700225cad9df49f053993 e8f682574e45b6406dadfffeb4 > ---------------- -------------------------- -------------------------- > %stddev change %stddev change %stddev > \ | \ | \ > 3405093 -19% 2747088 -2% 3348752 will-it-scale.per_process_ops > 1280 ± 3% -2% 1257 ± 3% -6% 1207 vmstat.system.cs > 2702 ± 18% 11% 3002 ± 19% 17% 3156 ± 18% numa-vmstat.node0.nr_mapped > 10765 ± 18% 11% 11964 ± 19% 17% 12588 ± 18% numa-meminfo.node0.Mapped > 0.00 ± 47% -40% 0.00 ± 45% -84% 0.00 ± 42% mpstat.cpu.soft% > > Thanks, > Xiaolong Thanks for the testing!