Date: Thu, 28 Apr 2011 11:31:26 +0100
From: Mel Gorman <mgorman@suse.de>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, Christoph Lameter <cl@linux.com>,
        Johannes Weiner <jweiner@redhat.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Rik van Riel <riel@redhat.com>, Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [RFC 2/8] compaction: make isolate_lru_page with filter aware
Message-ID: <20110428103126.GR4658@suse.de>
References: <cover.1303833415.git.minchan.kim@gmail.com>
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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@jp.fujitsu.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: Andrea Arcangeli <aarcange@redhat.com>
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>

Acked-by: Mel Gorman <mgorman@suse.de>

-- 
Mel Gorman
SUSE Labs
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