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Date: Fri, 2 Mar 2007 09:09:30 -0800 (PST)
From: Christoph Lameter <clameter@engr.sgi.com>
To: Nick Piggin <npiggin@suse.de>
cc: Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mel@skynet.ie>,
       mingo@elte.hu, jschopp@austin.ibm.com, arjan@infradead.org,
       torvalds@linux-foundation.org, mbligh@mbligh.org, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org
Subject: Re: The performance and behaviour of the anti-fragmentation related
 patches
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On Fri, 2 Mar 2007, Nick Piggin wrote:

> > Oh just run a 32GB SMP system with sparsely freeable pages and lots of 
> > allocs and frees and you will see it too. F.e try Linus tree and mlock 
> > a large portion of the memory and then see the fun starting. See also 
> > Rik's list of pathological cases on this.
> 
> Ah, so your problem is lots of unreclaimable pages. There are heaps
> of things we can try to reduce the rate at which we scan those.

Well this is one possible sympton of the basic issue of having too many 
page structs. I wonder how long we can patch things up.