netdev - Re: [PATCH 00/13] Swap-over-NBD without deadlocking

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Message-ID: <20110428133154.GA8572@ucw.cz>
Date:	Thu, 28 Apr 2011 15:31:55 +0200
From:	Pavel Machek <pavel@....cz>
To:	Mel Gorman <mgorman@...e.de>
Cc:	Linux-MM <linux-mm@...ck.org>,
	Linux-Netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>, Neil Brown <neilb@...e.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 00/13] Swap-over-NBD without deadlocking

Hi!


> For testing swap-over-NBD, a machine was booted with 2G of RAM with a
> swapfile backed by NBD. 16*NUM_CPU processes were started that create
> anonymous memory mappings and read them linearly in a loop. The total
> size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under
> memory pressure. Without the patches, the machine locks up within
> minutes and runs to completion with them applied.
> 
> Comments?

Nice!

It  is easy to see why swapping needs these fixes, but... dirty memory
writeout is used for memory clearing, too. Are same changes neccessary
to make that safe?

(Perhaps raise 'max dirty %' for testing?)
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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