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Message-Id: <20160330161141.4332b189e7a4930e117d765b@linux-foundation.org>
Date: Wed, 30 Mar 2016 16:11:41 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Minchan Kim <minchan@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
jlayton@...chiereds.net, bfields@...ldses.org,
Vlastimil Babka <vbabka@...e.cz>,
Joonsoo Kim <iamjoonsoo.kim@....com>, koct9i@...il.com,
aquini@...hat.com, virtualization@...ts.linux-foundation.org,
Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Rik van Riel <riel@...hat.com>, rknize@...orola.com,
Gioh Kim <gi-oh.kim@...fitbricks.com>,
Sangseok Lee <sangseok.lee@....com>,
Chan Gyun Jeong <chan.jeong@....com>,
Al Viro <viro@...IV.linux.org.uk>,
YiPing Xu <xuyiping@...ilicon.com>
Subject: Re: [PATCH v3 00/16] Support non-lru page migration
On Wed, 30 Mar 2016 16:11:59 +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 failed to fork easily.
>
> The problem was fragmentation caused by zram and GPU driver
> pages. Their pages cannot be migrated so compaction cannot
> work well, either so reclaimer ends up shrinking all of working
> set pages. It made system very slow and even to fail to fork
> easily.
>
> Other pain point is that they cannot work with CMA.
> Most of CMA memory space could be idle(ie, it could be used
> for movable pages unless driver is using) but if driver(i.e.,
> zram) cannot migrate his page, that memory space could be
> wasted. In our product which has big CMA memory, it reclaims
> zones too exccessively although there are lots of free space
> in CMA so system was very slow easily.
>
> To solve these problem, this patch try to add facility to
> migrate non-lru pages via introducing new friend functions
> of migratepage in address_space_operation and new page flags.
>
> (isolate_page, putback_page)
> (PG_movable, PG_isolated)
>
> For details, please read description in
> "mm/compaction: support non-lru movable page migration".
OK, I grabbed all these.
I wonder about testing coverage during the -next period. How many
people are likely to exercise these code paths in a serious way before
it all hits mainline?
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