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Subject: Re: [PATCH] Fix fake numa on ppc
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Rientjes <rientjes@google.com>
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Date: Wed, 02 Sep 2009 18:51:39 +1000
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Cc: linuxppc-dev@ozlabs.org, Ankita Garg <ankita@in.ibm.com>,
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On Tue, 2009-09-01 at 23:03 -0700, David Rientjes wrote:
> On Wed, 2 Sep 2009, Benjamin Herrenschmidt wrote:
> 
> > Since I'm pretty sure there could be CPU less nodes just like there
> > could be memory-less nodes, it would be good if fake numa could
> > simulate them too :-)
> > 
> 
> You don't want to simulate cpu less nodes since they do have affinity to 
> ranges of memory, you want to map each fake node to a cpumask including 
> all cpus with affinity to its memory, map each cpu to one fake node (with 
> memory) that it has physical affinity to, and then give all fake nodes 
> local NUMA distance to those on the same physical node.  Memoryless nodes 
> take care of themselves since they rely purely on node_distance(), so the 
> index into the slit for all fake nodes to those without memory will be the 
> same.

Ok, makes sense, thanks.

Cheers,
Ben.