From: Frans Pop <elendil@planet.nl>
To: Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH 3/3] vmscan: Force kswapd to take notice faster when high-order watermarks are being hit
Date: Mon, 2 Nov 2009 18:32:54 +0100
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Cc: Andrew Morton <akpm@linux-foundation.org>, stable@kernel.org,
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       Christoph Lameter <cl@linux-foundation.org>,
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References: <1256650833-15516-1-git-send-email-mel@csn.ul.ie> <20091028124756.7af44b6b.akpm@linux-foundation.org> <20091102160534.GA22046@csn.ul.ie>
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On Monday 02 November 2009, Mel Gorman wrote:
> vmscan: Help debug kswapd issues by counting number of rewakeups and
> premature sleeps
>
> There is a growing amount of anedotal evidence that high-order atomic
> allocation failures have been increasing since 2.6.31-rc1. The two
> strongest possibilities are a marked increase in the number of
> GFP_ATOMIC allocations and alterations in timing. Debugging printk
> patches have shown for example that kswapd is sleeping for shorter
> intervals and going to sleep when watermarks are still not being met.
>
> This patch adds two kswapd counters to help identify if timing is an
> issue. The first counter kswapd_highorder_rewakeup counts the number of
> times that kswapd stops reclaiming at one order and restarts at a higher
> order. The second counter kswapd_slept_prematurely counts the number of
> times kswapd went to sleep when the high watermark was not met.

What testing would you like done with this patch?
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