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Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19
From: Dave Hansen <haveblue@us.ibm.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: "Martin J. Bligh" <mbligh@mbligh.org>, Mel Gorman <mel@csn.ul.ie>,
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Date: Thu, 03 Nov 2005 18:48:46 +0100
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On Thu, 2005-11-03 at 09:19 -0800, Linus Torvalds wrote:
> On Thu, 3 Nov 2005, Martin J. Bligh wrote:
> > 
> > The problem is how these zones get resized. Can we hotplug memory between 
> > them, with some sparsemem like indirection layer?
> 
> I think you should be able to add them. You can remove them. But you can't 
> resize them.

Any particular reasons you think we can't resize them?  I know shrinking
the non-reclaim (DMA,NORMAL) zones will be practically impossible, but
it should be quite possible to shrink the reclaim zone, and grow DMA or
NORMAL into it.

This will likely be necessary as memory is added to a system, and the
ratio of reclaim to non-reclaim zones gets out of whack and away from
the magic 16:1 or 8:1 highmem:normal ratio that seems popular.

-- Dave