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From: Mel Gorman <mgorman@suse.de>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: add per-zone lru list stat
Date: Wed, 20 Jul 2016 11:55:49 +0100	[thread overview]
Message-ID: <20160720105549.GU11400@suse.de> (raw)
In-Reply-To: <20160720001624.GA25472@bbox>

On Wed, Jul 20, 2016 at 09:16:24AM +0900, Minchan Kim wrote:
> On Tue, Jul 19, 2016 at 05:48:57PM +0100, Mel Gorman wrote:
> > On Wed, Jul 20, 2016 at 12:50:32AM +0900, Minchan Kim wrote:
> > > While I did stress test with hackbench, I got OOM message frequently
> > > which didn't ever happen in zone-lru.
> > > 
> > 
> > This one also showed pgdat going unreclaimable early. Have you tried any
> > of the three oom-related patches I sent to Joonsoo to see what impact,
> > if any, it had?
> 
> Before the result, I want to say goal of this patch, again.
> Without per-zone lru stat, it's really hard to debug OOM problem in
> multiple zones system so regardless of solving the problem, we should add
> per-zone lru stat for debuggability of OOM which has been never perfect
> solution, ever.
> 

That's not in dispute, I simply wanted to know the impact.

> The result is not OOM but hackbench stalls forever.

Ok, that points to both the premature marking pgdats as unreclaimable
and the inactive rotation are both problems.

I have a series prepared that may or may not address the problem. I'm
trying to reproduce the OOM killer on a 32-bit KVM but so far so luck.
If I fail to reproduce it then I cannot tell if the series has an impact
and may have to post it and hope you and Joonsoo can test it.

-- 
Mel Gorman
SUSE Labs

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      reply	other threads:[~2016-07-20 10:55 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-19 15:50 [PATCH 1/2] mm: add per-zone lru list stat Minchan Kim
2016-07-19 15:50 ` [PATCH 2/2] mm: consider per-zone inactive ratio to deactivate Minchan Kim
2016-07-19 16:48 ` [PATCH 1/2] mm: add per-zone lru list stat Mel Gorman
2016-07-20  0:16   ` Minchan Kim
2016-07-20 10:55     ` Mel Gorman [this message]

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