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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 C22BFC43441 for ; Tue, 27 Nov 2018 18:21:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 955F52086B for ; Tue, 27 Nov 2018 18:21:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 955F52086B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732054AbeK1FUY (ORCPT ); Wed, 28 Nov 2018 00:20:24 -0500 Received: from mx2.suse.de ([195.135.220.15]:50376 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726234AbeK1FUY (ORCPT ); Wed, 28 Nov 2018 00:20:24 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 4D8C6AFF6; Tue, 27 Nov 2018 18:21:38 +0000 (UTC) Date: Tue, 27 Nov 2018 19:21:37 +0100 From: Michal Hocko To: Linus Torvalds Cc: rong.a.chen@intel.com, Andrea Arcangeli , s.priebe@profihost.ag, alex.williamson@redhat.com, mgorman@techsingularity.net, zi.yan@cs.rutgers.edu, Vlastimil Babka , rientjes@google.com, kirill@shutemov.name, Andrew Morton , Linux List Kernel Mailing , lkp@01.org Subject: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3% regression Message-ID: <20181127182137.GE6923@dhcp22.suse.cz> References: <20181127062503.GH6163@shao2-debian> <20181127181727.GD6923@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20181127181727.GD6923@dhcp22.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 27-11-18 19:17:27, Michal Hocko wrote: > On Tue 27-11-18 09:08:50, Linus Torvalds wrote: > > On Mon, Nov 26, 2018 at 10:24 PM kernel test robot > > wrote: > > > > > > FYI, we noticed a -61.3% regression of vm-scalability.throughput due > > > to commit ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for > > > MADV_HUGEPAGE mappings") > > > > Well, that's certainly noticeable and not good. > > > > Andrea, I suspect it might be causing fights with auto numa migration.. > > > > Lots more system time, but also look at this: > > > > > 1122389 ± 9% +17.2% 1315380 ± 4% proc-vmstat.numa_hit > > > 214722 ± 5% +21.6% 261076 ± 3% proc-vmstat.numa_huge_pte_updates > > > 1108142 ± 9% +17.4% 1300857 ± 4% proc-vmstat.numa_local > > > 145368 ± 48% +63.1% 237050 ± 17% proc-vmstat.numa_miss > > > 159615 ± 44% +57.6% 251573 ± 16% proc-vmstat.numa_other > > > 185.50 ± 81% +8278.6% 15542 ± 40% proc-vmstat.numa_pages_migrated > > > > Should the commit be reverted? Or perhaps at least modified? > > Well, the commit is trying to revert to the behavior before > 5265047ac301 because there are real usecases that suffered from that > change and bug reports as a result of that. > > will-it-scale is certainly worth considering but it is an artificial > testcase. A higher NUMA miss rate is an expected side effect of the > patch because the fallback to a different NUMA node is more likely. The > __GFP_THISNODE side effect is basically introducing node-reclaim > behavior for THPages. Another thing is that there is no good behavior > for everybody. Reclaim locally vs. THP on a remote node is hard to > tell by default. We have discussed that at length and there were some > conclusions. One of them is that we need a numa policy to tell whether > a expensive localility is preferred over remote allocation. Also we > definitely need a better pro-active defragmentation to allow larger > pages on a local node. This is a work in progress and this patch is a > stop gap fix. Btw. the associated discussion is http://lkml.kernel.org/r/20180925120326.24392-1-mhocko@kernel.org -- Michal Hocko SUSE Labs