From: Michal Hocko <mhocko@kernel.org>
To: Nils Holland <nholland@tisys.org>
Cc: Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.cz>,
linux-btrfs@vger.kernel.org
Subject: Re: [RFC PATCH] mm, memcg: fix (Re: OOM: Better, but still there on)
Date: Wed, 28 Dec 2016 09:57:59 +0100 [thread overview]
Message-ID: <20161228085759.GD11470@dhcp22.suse.cz> (raw)
In-Reply-To: <20161227193308.GA17454@boerne.fritz.box>
On Tue 27-12-16 20:33:09, Nils Holland wrote:
> 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.
yes, sorry about the confusion
> 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.
yes that seems to be a variation of the workload I would say because if
anything the patch should reduce the number of scanned pages.
> 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
In these cases there is no real difference because this is not the
lowmem pressure because those requests can go to the highmem zone.
> 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.
yes, a stronger memory pressure would be needed. I suspect that your
original issues was more about active list aging than a really strong
memory pressure. So it might be possible that your workload will not
notice. If you can collect those two tracepoints over a longer time it
can still tell us something but I do not want you to burn a lot of time
on this. The main issue seems to be fixed and the follow up fix can wait
for a throughout review after both Mel and Johannes are back from
holiday.
> 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.
Thanks!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-12-28 8:58 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-15 22:57 OOM: Better, but still there on 4.9 Nils Holland
2016-12-16 7:39 ` Michal Hocko
2016-12-16 15:58 ` OOM: Better, but still there on Michal Hocko
2016-12-16 15:58 ` [PATCH 1/2] mm: consolidate GFP_NOFAIL checks in the allocator slowpath Michal Hocko
2016-12-16 15:58 ` [PATCH 2/2] mm, oom: do not enfore OOM killer for __GFP_NOFAIL automatically Michal Hocko
2016-12-16 17:31 ` Johannes Weiner
2016-12-16 22:12 ` Michal Hocko
2016-12-17 11:17 ` Tetsuo Handa
2016-12-18 16:37 ` Michal Hocko
2016-12-16 18:47 ` OOM: Better, but still there on Nils Holland
2016-12-17 0:02 ` Michal Hocko
2016-12-17 12:59 ` Nils Holland
2016-12-17 14:44 ` Tetsuo Handa
2016-12-17 17:11 ` Nils Holland
2016-12-17 21:06 ` Nils Holland
2016-12-18 5:14 ` Tetsuo Handa
2016-12-19 13:45 ` Michal Hocko
2016-12-20 2:08 ` Nils Holland
2016-12-21 7:36 ` Michal Hocko
2016-12-21 11:00 ` Tetsuo Handa
2016-12-21 11:16 ` Michal Hocko
2016-12-21 14:04 ` Chris Mason
2016-12-22 10:10 ` Nils Holland
2016-12-22 10:27 ` Michal Hocko
2016-12-22 10:35 ` Nils Holland
2016-12-22 10:46 ` Tetsuo Handa
2016-12-22 19:17 ` Michal Hocko
2016-12-22 21:46 ` Nils Holland
2016-12-23 10:51 ` Michal Hocko
2016-12-23 12:18 ` Nils Holland
2016-12-23 12:57 ` Michal Hocko
2016-12-23 14:47 ` [RFC PATCH] mm, memcg: fix (Re: OOM: Better, but still there on) Michal Hocko
2016-12-23 22:26 ` Nils Holland
2016-12-26 12:48 ` Michal Hocko
2016-12-26 18:57 ` Nils Holland
2016-12-27 8:08 ` Michal Hocko
2016-12-27 11:23 ` Nils Holland
2016-12-27 11:27 ` Michal Hocko
2016-12-27 15:55 ` Michal Hocko
2016-12-27 16:28 ` [PATCH] mm, vmscan: consider eligible zones in get_scan_count kbuild test robot
2016-12-28 8:51 ` Michal Hocko
2016-12-27 19:33 ` [RFC PATCH] mm, memcg: fix (Re: OOM: Better, but still there on) Nils Holland
2016-12-28 8:57 ` Michal Hocko [this message]
2016-12-29 1:20 ` Minchan Kim
2016-12-29 9:04 ` Michal Hocko
2016-12-30 2:05 ` Minchan Kim
2016-12-30 10:40 ` Michal Hocko
2016-12-29 0:31 ` Minchan Kim
2016-12-29 0:48 ` Minchan Kim
2016-12-29 8:52 ` Michal Hocko
2016-12-30 10:19 ` Mel Gorman
2016-12-30 11:05 ` Michal Hocko
2016-12-30 12:43 ` Mel Gorman
2016-12-25 22:25 ` [lkp-developer] [mm, memcg] d18e2b2aca: WARNING:at_mm/memcontrol.c:#mem_cgroup_update_lru_size kernel test robot
2016-12-26 12:26 ` Michal Hocko
2016-12-26 12:50 ` Michal Hocko
2016-12-18 0:28 ` OOM: Better, but still there on Xin Zhou
2016-12-16 18:15 ` OOM: Better, but still there on 4.9 Chris Mason
2016-12-16 22:14 ` Michal Hocko
2016-12-16 22:47 ` Chris Mason
2016-12-16 23:31 ` Michal Hocko
2016-12-16 19:50 ` Chris Mason
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