Re: [RFC 2/8] compaction: make isolate_lru_page with filter aware

From: Mel Gorman
Date: Thu Apr 28 2011 - 06:31:35 EST


On Wed, Apr 27, 2011 at 01:25:19AM +0900, Minchan Kim wrote:
> In async mode, compaction doesn't migrate dirty or writeback pages.
> So, it's meaningless to pick the page and re-add it to lru list.
>
> Of course, when we isolate the page in compaction, the page might
> be dirty or writeback but when we try to migrate the page, the page
> would be not dirty, writeback. So it could be migrated. But it's
> very unlikely as isolate and migration cycle is much faster than
> writeout.
>
> So, this patch helps cpu and prevent unnecessary LRU churning.
>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>

Acked-by: Mel Gorman <mgorman@xxxxxxx>

--
Mel Gorman
SUSE Labs
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