Re: [patch 2/2] enables booting a NUMA system where some nodes have no memory

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Wed, 15 Nov 2006 16:57:56 -0800 (PST)
Christoph Lameter <clameter@sgi.com> wrote:
> numa_node_id() points to this and we always get allocations redirected to 
> other nodes. The slab duplicates its per node structures on the fallback 
> node.
> 
> > The zonelist[] donen't contain empty-zone.
> 
> So we will never encounter that zone except when going to the 
> pglist_data struct through numa_node_id()?
> 
Some pgdat/zone scanning code will access it.
See: for_each_zone() and populated_zone().

AFAIK, in 2.6.9 age(means RHEL4), cpus on memory-less-node are moved to the
nearest node. And there were no useless pgdat.

Now, there are memory-less-node. Cpus on memory-less-node are on a pgdat
with empty-zone. I think this is very simple way rather than remapping.
And I think cpus on memory-less-node are sharing something (FSB,switch,etc..)
Tieing cpus to a memory-less-node may have some benefit. 

-Kame

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