linux-kernel - Re: [PATCH] mm: cma: Discard clean pages during contiguous allocation instead of migration

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Message-ID: <CAH9JG2V-ATcfe5_YkH6sMmm5UZFHt2SYBWnCNSpfsncGFU96mg@mail.gmail.com>
Date:	Tue, 11 Sep 2012 20:23:14 +0900
From:	Kyungmin Park <kmpark@...radead.org>
To:	Michal Nazarewicz <mina86@...a86.com>
Cc:	Minchan Kim <minchan@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>
Subject: Re: [PATCH] mm: cma: Discard clean pages during contiguous allocation
 instead of migration

On 9/11/12, Michal Nazarewicz <mina86@...a86.com> wrote:
>
> On Tue, Sep 11 2012, Minchan Kim wrote:
>> This patch drops clean cache pages instead of migration during
>> alloc_contig_range() to minimise allocation latency by reducing the
>> amount
>> of migration is necessary. It's useful for CMA because latency of
>> migration
>> is more important than evicting the background processes working set.
>> In addition, as pages are reclaimed then fewer free pages for migration
>> targets are required so it avoids memory reclaiming to get free pages,
>> which is a contributory factor to increased latency.
>>
>> * from v1
>>   * drop migrate_mode_t
>>   * add reclaim_clean_pages_from_list instad of MIGRATE_DISCARD support -
>> Mel
>>
>> I measured elapsed time of __alloc_contig_migrate_range which migrates
>> 10M in 40M movable zone in QEMU machine.
>>
>> Before - 146ms, After - 7ms
>>
>> Cc: Marek Szyprowski <m.szyprowski@...sung.com>
>> Cc: Michal Nazarewicz <mina86@...a86.com>
>
> Acked-by: Michal Nazarewicz <mina86@...a86.com>
Tested-by: Kyungmin Park <kyungmin.park@...sung.com>
>
> Thanks!
>
> --
> Best regards,                                         _     _
> .o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
> ..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
> ooo +----<email/xmpp: mpn@...gle.com>--------------ooO--(_)--Ooo--
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