From: Minchan Kim <minchan@kernel.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Nils Holland <nholland@tisys.org>, 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: Fri, 30 Dec 2016 11:05:22 +0900 [thread overview]
Message-ID: <20161230020522.GC4184@bbox> (raw)
In-Reply-To: <20161229090432.GE29208@dhcp22.suse.cz>
On Thu, Dec 29, 2016 at 10:04:32AM +0100, Michal Hocko wrote:
> On Thu 29-12-16 10:20:26, Minchan Kim 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.
> > >
> > > I would also appreciate if Mel and Johannes had a look at it. I am not
> > > yet sure whether we need the same thing for anon/file balancing in
> > > get_scan_count. I suspect we need but need to think more about that.
> > >
> > > Thanks a lot again!
> > > ---
> > > From b51f50340fe9e40b68be198b012f8ab9869c1850 Mon Sep 17 00:00:00 2001
> > > From: Michal Hocko <mhocko@suse.com>
> > > Date: Tue, 27 Dec 2016 16:28:44 +0100
> > > Subject: [PATCH] mm, vmscan: consider eligible zones in get_scan_count
> > >
> > > get_scan_count considers the whole node LRU size when
> > > - doing SCAN_FILE due to many page cache inactive pages
> > > - calculating the number of pages to scan
> > >
> > > in both cases this might lead to unexpected behavior especially on 32b
> > > systems where we can expect lowmem memory pressure very often.
> > >
> > > A large highmem zone can easily distort SCAN_FILE heuristic because
> > > there might be only few file pages from the eligible zones on the node
> > > lru and we would still enforce file lru scanning which can lead to
> > > trashing while we could still scan anonymous pages.
> >
> > Nit:
> > It doesn't make thrashing because isolate_lru_pages filter out them
> > but I agree it makes pointless CPU burning to find eligible pages.
>
> This is not about isolate_lru_pages. The trashing could happen if we had
> lowmem pagecache user which would constantly reclaim recently faulted
> in pages while there is anonymous memory in the lowmem which could be
> reclaimed instead.
>
> [...]
> > > /*
> > > + * Return the number of pages on the given lru which are eligibne for the
> > eligible
>
> fixed
>
> > > + * given zone_idx
> > > + */
> > > +static unsigned long lruvec_lru_size_zone_idx(struct lruvec *lruvec,
> > > + enum lru_list lru, int zone_idx)
> >
> > Nit:
> >
> > Although there is a comment, function name is rather confusing when I compared
> > it with lruvec_zone_lru_size.
>
> I am all for a better name.
>
> > lruvec_eligible_zones_lru_size is better?
>
> this would be too easy to confuse with lruvec_eligible_zone_lru_size.
> What about lruvec_lru_size_eligible_zones?
Don't mind.
>
> > Nit:
> >
> > With this patch, inactive_list_is_low can use lruvec_lru_size_zone_idx rather than
> > own custom calculation to filter out non-eligible pages.
>
> Yes, that would be possible and I was considering that. But then I found
> useful to see total and reduced numbers in the tracepoint
> http://lkml.kernel.org/r/20161228153032.10821-8-mhocko@kernel.org
> and didn't want to call lruvec_lru_size 2 times. But if you insist then
> I can just do that.
I don't mind either but I think we need to describe the reason if you want to
go with your open-coded version. Otherwise, someone will try to fix it.
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next prev parent reply other threads:[~2016-12-30 2:05 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20161215225702.GA27944@boerne.fritz.box>
2016-12-16 7:39 ` OOM: Better, but still there on 4.9 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
2016-12-29 1:20 ` Minchan Kim
2016-12-29 9:04 ` Michal Hocko
2016-12-30 2:05 ` Minchan Kim [this message]
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
2016-12-16 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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