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Date: Tue, 14 Feb 2012 17:29:02 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-media@vger.kernel.org, linux-mm@kvack.org,
        linaro-mm-sig@lists.linaro.org, Michal Nazarewicz <mina86@mina86.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Russell King <linux@arm.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Daniel Walker <dwalker@codeaurora.org>, Mel Gorman <mel@csn.ul.ie>,
        Arnd Bergmann <arnd@arndb.de>, Jesse Barker <jesse.barker@linaro.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Shariq Hasnain <shariq.hasnain@linaro.org>,
        Chunsang Jeong <chunsang.jeong@linaro.org>,
        Dave Hansen <dave@linux.vnet.ibm.com>,
        Benjamin Gaignard <benjamin.gaignard@linaro.org>,
        Rob Clark <rob.clark@linaro.org>, Ohad Ben-Cohen <ohad@wizery.com>
Subject: Re: [PATCHv21 08/16] mm: mmzone: MIGRATE_CMA migration type added
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On Fri, 10 Feb 2012 18:32:23 +0100
Marek Szyprowski <m.szyprowski@samsung.com> wrote:

> From: Michal Nazarewicz <mina86@mina86.com>
> 
> The MIGRATE_CMA migration type has two main characteristics:
> (i) only movable pages can be allocated from MIGRATE_CMA
> pageblocks and (ii) page allocator will never change migration
> type of MIGRATE_CMA pageblocks.
> 
> This guarantees (to some degree) that page in a MIGRATE_CMA page
> block can always be migrated somewhere else (unless there's no
> memory left in the system).
> 
> It is designed to be used for allocating big chunks (eg. 10MiB)
> of physically contiguous memory.  Once driver requests
> contiguous memory, pages from MIGRATE_CMA pageblocks may be
> migrated away to create a contiguous block.
> 
> To minimise number of migrations, MIGRATE_CMA migration type
> is the last type tried when page allocator falls back to other
> migration types when requested.
> 
> Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> Acked-by: Mel Gorman <mel@csn.ul.ie>
> Tested-by: Rob Clark <rob.clark@linaro.org>
> Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>