linux-kernel - Re: [PATCH 1/2] mm: page allocator: Adjust the per-cpu counter threshold when memory is low

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Message-ID: <20101126160619.GP22651@bombadil.infradead.org>
Date:	Fri, 26 Nov 2010 11:06:19 -0500
From:	Kyle McMartin <kyle@...artin.ca>
To:	Mel Gorman <mel@....ul.ie>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Shaohua Li <shaohua.li@...el.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Christoph Lameter <cl@...ux.com>,
	David Rientjes <rientjes@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH 1/2] mm: page allocator: Adjust the per-cpu counter
 threshold when memory is low

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@...el.com>
> Signed-off-by: Mel Gorman <mel@....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
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