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Date: Mon, 04 Mar 2002 08:59:10 -0800
From: "Martin J. Bligh" <Martin.Bligh@us.ibm.com>
To: Rik van Riel <riel@conectiva.com.br>, Andrea Arcangeli <andrea@suse.de>
cc: Daniel Phillips <phillips@bonn-fries.net>,
        Bill Davidsen <davidsen@tmr.com>, Mike Fedyk <mfedyk@matchmail.com>,
        linux-kernel@vger.kernel.org
Subject: Re: 2.4.19pre1aa1
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> Not stability per se, but you have to admit the VM tends to
> behave badly when there's a shortage in just one memory zone.
> I believe NUMA will only make this situation worse.

rmap would seem to buy us (at least) two major things for NUMA:

1) We can balance between zones easier by "swapping out"
pages to another zone.

2) We can do local per-node scanning - no need to bounce
information to and fro across the interconnect just to see what's
worth swapping out.

I suspect that the performance of NUMA under memory pressure
without the rmap stuff will be truly horrific, as we decend into 
a cache-trashing page transfer war. 

I can't see any way to fix this without some sort of rmap - any
other suggestions as to how this might be done?

Thanks,

Martin.

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