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

From: Michal Nazarewicz
Date: Tue Sep 11 2012 - 07:15:59 EST



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@xxxxxxxxxxx>
> Cc: Michal Nazarewicz <mina86@xxxxxxxxxx>

Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>

Thanks!

--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, MichaÅ âmina86â Nazarewicz (o o)
ooo +----<email/xmpp: mpn@xxxxxxxxxx>--------------ooO--(_)--Ooo--

Attachment: pgp00000.pgp
Description: PGP signature