From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id E897C6B02B4 for ; Tue, 8 Aug 2017 00:23:39 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id l2so24065139pgu.2 for ; Mon, 07 Aug 2017 21:23:39 -0700 (PDT) Received: from mail-pg0-x242.google.com (mail-pg0-x242.google.com. [2607:f8b0:400e:c05::242]) by mx.google.com with ESMTPS id g15si303510pli.354.2017.08.07.21.23.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Aug 2017 21:23:38 -0700 (PDT) Received: by mail-pg0-x242.google.com with SMTP id y129so2023622pgy.3 for ; Mon, 07 Aug 2017 21:23:38 -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: <20170808022830.GA28570@bbox> Date: Mon, 7 Aug 2017 21:23:34 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: <93CA4B47-95C2-43A2-8E92-B142CAB1DAF7@gmail.com> References: <20170802000818.4760-7-namit@vmware.com> <20170808011923.GE25554@yexl-desktop> <20170808022830.GA28570@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: kernel test robot , "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: > 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? 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. 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=E2=80=99ll try to profile the workload - but = feel free to beat me to it. Nadav=20 -- 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