linux-kernel - Re: [PATCH v7 00/12] Support non-lru page migration

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Date:	Wed, 1 Jun 2016 14:41:51 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Minchan Kim <minchan@...nel.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Vlastimil Babka <vbabka@...e.cz>,
	dri-devel@...ts.freedesktop.org, Hugh Dickins <hughd@...gle.com>,
	John Einar Reitan <john.reitan@...s.arm.com>,
	Jonathan Corbet <corbet@....net>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Konstantin Khlebnikov <koct9i@...il.com>,
	Mel Gorman <mgorman@...e.de>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Rafael Aquini <aquini@...hat.com>,
	Rik van Riel <riel@...hat.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	virtualization@...ts.linux-foundation.org,
	Gioh Kim <gi-oh.kim@...fitbricks.com>,
	Chan Gyun Jeong <chan.jeong@....com>,
	Sangseok Lee <sangseok.lee@....com>,
	Kyeongdon Kim <kyeongdon.kim@....com>,
	Chulmin Kim <cmlaika.kim@...sung.com>
Subject: Re: [PATCH v7 00/12] Support non-lru page migration

On Wed,  1 Jun 2016 08:21:09 +0900 Minchan Kim <minchan@...nel.org> wrote:

> Recently, I got many reports about perfermance degradation in embedded
> system(Android mobile phone, webOS TV and so on) and easy fork fail.
> 
> The problem was fragmentation caused by zram and GPU driver mainly.
> With memory pressure, their pages were spread out all of pageblock and
> it cannot be migrated with current compaction algorithm which supports
> only LRU pages. In the end, compaction cannot work well so reclaimer
> shrinks all of working set pages. It made system very slow and even to
> fail to fork easily which requires order-[2 or 3] allocations.
> 
> Other pain point is that they cannot use CMA memory space so when OOM
> kill happens, I can see many free pages in CMA area, which is not
> memory efficient. In our product which has big CMA memory, it reclaims
> zones too exccessively to allocate GPU and zram page although there are
> lots of free space in CMA so system becomes very slow easily.

But this isn't presently implemented for GPU drivers or for CMA, yes?

What's the story there?