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Date: Fri, 26 Nov 2010 11:06:19 -0500
From: Kyle McMartin <kyle@mcmartin.ca>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Shaohua Li <shaohua.li@intel.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Christoph Lameter <cl@linux.com>, David Rientjes <rientjes@google.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        LKML <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH 1/2] mm: page allocator: Adjust the per-cpu counter
 threshold when memory is low
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On Wed, Oct 27, 2010 at 09:47:35AM +0100, Mel Gorman wrote:
><snip>
> To ensure that kswapd wakes up, a safe version of zone_watermark_ok()
> is introduced that takes a more accurate reading of NR_FREE_PAGES when
> called from wakeup_kswapd, when deciding whether it is really safe to go
> back to sleep in sleeping_prematurely() and when deciding if a zone is
> really balanced or not in balance_pgdat(). We are still using an expensive
> function but limiting how often it is called.
><snip>
> Reported-by: Shaohua Li <shaohua.li@intel.com>
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>

Hi Mel,

I notice these aren't flagged for stable, should they be? (They fairly
trivially apply and compile on 2.6.36 barring the trace_ points which
changed.) I've got a few bug reports against .36/.37 where kswapd has
been sleeping for 60s+.

I built them some kernels with these patches, but haven't heard back yet
as to whether it fixes things for them.

Thanks for any insight,
	Kyle