From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 342296B02B4 for ; Thu, 10 Aug 2017 00:14:56 -0400 (EDT) Received: by mail-pg0-f69.google.com with SMTP id r133so84654757pgr.6 for ; Wed, 09 Aug 2017 21:14:56 -0700 (PDT) Received: from mail-pg0-x244.google.com (mail-pg0-x244.google.com. [2607:f8b0:400e:c05::244]) by mx.google.com with ESMTPS id x8si3428461pgc.689.2017.08.09.21.14.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Aug 2017 21:14:55 -0700 (PDT) Received: by mail-pg0-x244.google.com with SMTP id 83so7492004pgb.4 for ; Wed, 09 Aug 2017 21:14:54 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [lkp-robot] [mm] 7674270022: will-it-scale.per_process_ops -19.3% regression From: Nadav Amit In-Reply-To: <20170810041353.GB2042@bbox> Date: Wed, 9 Aug 2017 21:14:50 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: <80589593-6F0E-4421-9279-681D5B388100@gmail.com> 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> <20170810041353.GB2042@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Ye Xiaolong , "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 Minchan Kim wrote: > 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: >>>>=20 >>>>> Minchan Kim wrote: >>>>>=20 >>>>>> Hi, >>>>>>=20 >>>>>> On Tue, Aug 08, 2017 at 09:19:23AM +0800, kernel test robot = wrote: >>>>>>> Greeting, >>>>>>>=20 >>>>>>> FYI, we noticed a -19.3% regression of = will-it-scale.per_process_ops due to commit: >>>>>>>=20 >>>>>>>=20 >>>>>>> commit: 76742700225cad9df49f05399381ac3f1ec3dc60 ("mm: fix = MADV_[FREE|DONTNEED] TLB flush miss problem") >>>>>>> url: = https://github.com/0day-ci/linux/commits/Nadav-Amit/mm-migrate-prevent-rac= y-access-to-tlb_flush_pending/20170802-205715 >>>>>>>=20 >>>>>>>=20 >>>>>>> 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: >>>>>>>=20 >>>>>>> nr_task: 16 >>>>>>> mode: process >>>>>>> test: brk1 >>>>>>> cpufreq_governor: performance >>>>>>>=20 >>>>>>> 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 >>>>>>=20 >>>>>> Thanks for the report. >>>>>> Could you explain what kinds of workload you are testing? >>>>>>=20 >>>>>> Does it calls frequently madvise(MADV_DONTNEED) in parallel on = multiple >>>>>> threads? >>>>>=20 >>>>> According to the description it is "testcase:brk increase/decrease = of one >>>>> page=E2=80=9D. According to the mode it spawns multiple processes, = not threads. >>>>>=20 >>>>> 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(). >>>>>=20 >>>>> If I find some free time, I=E2=80=99ll try to profile the workload = - but feel free >>>>> to beat me to it. >>>>=20 >>>> 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? >>>=20 >>> Oops, but with second looking, it seems it's not my fault. ;-) >>> https://marc.info/?l=3Dlinux-mm&m=3D150156699114088&w=3D2 >>>=20 >>> Anyway, thanks for the pointing out. >>> xiaolong.ye, could you retest with this fix? >>=20 >> 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. >>=20 >> 378005bdbac0a2ec 76742700225cad9df49f053993 = e8f682574e45b6406dadfffeb4 =20 >> ---------------- -------------------------- = -------------------------- =20 >> %stddev change %stddev change = %stddev >> \ | \ | \ = =20 >> 3405093 -19% 2747088 -2% 3348752 = will-it-scale.per_process_ops >> 1280 =C2=B1 3% -2% 1257 =C2=B1 3% -6% = 1207 vmstat.system.cs >> 2702 =C2=B1 18% 11% 3002 =C2=B1 19% 17% = 3156 =C2=B1 18% numa-vmstat.node0.nr_mapped >> 10765 =C2=B1 18% 11% 11964 =C2=B1 19% 17% = 12588 =C2=B1 18% numa-meminfo.node0.Mapped >> 0.00 =C2=B1 47% -40% 0.00 =C2=B1 45% -84% = 0.00 =C2=B1 42% mpstat.cpu.soft% >>=20 >> Thanks, >> Xiaolong >=20 > Thanks for the testing! Sorry again for screwing your patch, Minchan. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org