Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933224AbcL0Td1 (ORCPT ); Tue, 27 Dec 2016 14:33:27 -0500 Received: from celine.tisys.org ([85.25.117.166]:47406 "EHLO celine.tisys.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932997AbcL0TdR (ORCPT ); Tue, 27 Dec 2016 14:33:17 -0500 Date: Tue, 27 Dec 2016 20:33:09 +0100 From: Nils Holland To: Michal Hocko Cc: Mel Gorman , Johannes Weiner , Vladimir Davydov , Tetsuo Handa , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Chris Mason , David Sterba , linux-btrfs@vger.kernel.org Subject: Re: [RFC PATCH] mm, memcg: fix (Re: OOM: Better, but still there on) Message-ID: <20161227193308.GA17454@boerne.fritz.box> References: <20161222101028.GA11105@ppc-nas.fritz.box> <20161222191719.GA19898@dhcp22.suse.cz> <20161222214611.GA3015@boerne.fritz.box> <20161223105157.GB23109@dhcp22.suse.cz> <20161223121851.GA27413@ppc-nas.fritz.box> <20161223125728.GE23109@dhcp22.suse.cz> <20161223144738.GB23117@dhcp22.suse.cz> <20161223222559.GA5568@teela.multi.box> <20161226124839.GB20715@dhcp22.suse.cz> <20161227155532.GI1308@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161227155532.GI1308@dhcp22.suse.cz> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5401 Lines: 77 On Tue, Dec 27, 2016 at 04:55:33PM +0100, Michal Hocko wrote: > Hi, > could you try to run with the following patch on top of the previous > one? I do not think it will make a large change in your workload but > I think we need something like that so some testing under which is known > to make a high lowmem pressure would be really appreciated. If you have > more time to play with it then running with and without the patch with > mm_vmscan_direct_reclaim_{start,end} tracepoints enabled could tell us > whether it make any difference at all. Of course, no problem! First, about the events to trace: mm_vmscan_direct_reclaim_start doesn't seem to exist, but mm_vmscan_direct_reclaim_begin does. I'm sure that's what you meant and so I took that one instead. Then I have to admit in both cases (once without the latest patch, once with) very little trace data was actually produced. In the case without the patch, the reclaim was started more often and reclaimed a smaller number of pages each time, in the case with the patch it was invoked less often, and with the last time it was invoked it reclaimed a rather big number of pages. I have no clue, however, if that happened "by chance" or if it was actually causes by the patch and thus an expected change. In both cases, my test case was: Reboot, setup logging, do "emerge firefox" (which unpacks and builds the firefox sources), then, when the emerge had come so far that the unpacking was done and the building had started, switch to another console and untar the latest kernel, libreoffice and (once more) firefox sources there. After that had completed, I aborted the emerge build process and stopped tracing. Here's the trace data captured without the latest patch applied: khugepaged-22 [000] .... 566.123383: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [000] .N.. 566.165520: mm_vmscan_direct_reclaim_end: nr_reclaimed=1100 khugepaged-22 [001] .... 587.515424: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [000] .... 587.596035: mm_vmscan_direct_reclaim_end: nr_reclaimed=1029 khugepaged-22 [001] .... 599.879536: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [000] .... 601.000812: mm_vmscan_direct_reclaim_end: nr_reclaimed=1100 khugepaged-22 [001] .... 601.228137: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 601.309952: mm_vmscan_direct_reclaim_end: nr_reclaimed=1081 khugepaged-22 [001] .... 694.935267: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .N.. 695.081943: mm_vmscan_direct_reclaim_end: nr_reclaimed=1071 khugepaged-22 [001] .... 701.370707: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 701.372798: mm_vmscan_direct_reclaim_end: nr_reclaimed=1089 khugepaged-22 [001] .... 764.752036: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [000] .... 771.047905: mm_vmscan_direct_reclaim_end: nr_reclaimed=1039 khugepaged-22 [000] .... 781.760515: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 781.826543: mm_vmscan_direct_reclaim_end: nr_reclaimed=1040 khugepaged-22 [001] .... 782.595575: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [000] .... 782.638591: mm_vmscan_direct_reclaim_end: nr_reclaimed=1040 khugepaged-22 [001] .... 782.930455: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 782.993608: mm_vmscan_direct_reclaim_end: nr_reclaimed=1040 khugepaged-22 [001] .... 783.330378: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 783.369653: mm_vmscan_direct_reclaim_end: nr_reclaimed=1040 And this is the same with the patch applied: khugepaged-22 [001] .... 523.599997: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 523.683110: mm_vmscan_direct_reclaim_end: nr_reclaimed=1092 khugepaged-22 [001] .... 535.345477: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 535.401189: mm_vmscan_direct_reclaim_end: nr_reclaimed=1078 khugepaged-22 [000] .... 692.876716: mm_vmscan_direct_reclaim_begin: order=9 may_writepage=1 gfp_flags=GFP_TRANSHUGE classzone_idx=3 khugepaged-22 [001] .... 703.312399: mm_vmscan_direct_reclaim_end: nr_reclaimed=197759 If my test case and thus the results don't sound good, I could of course try some other test cases ... like capturing for a longer period of time or trying to produce more memory pressure by running more processes at the same time, or something like that. Besides that I can say that the patch hasn't produced any warnings or other issues so far, so at first glance, it doesn't seem to hurt anything. Greetings Nils