[RFC PATCH 2/3] topology: support node_numa_mem() for determining the fallback node

[Christoph Lameter]

On Mon, 17 Feb 2014, Joonsoo Kim wrote:

> On Wed, Feb 12, 2014 at 10:51:37PM -0800, Nishanth Aravamudan wrote:
> > Hi Joonsoo,
> > Also, given that only ia64 and (hopefuly soon) ppc64 can set
> > CONFIG_HAVE_MEMORYLESS_NODES, does that mean x86_64 can't have
> > memoryless nodes present? Even with fakenuma? Just curious.

x86_64 currently does not support memoryless nodes otherwise it would
have set CONFIG_HAVE_MEMORYLESS_NODES in the kconfig. Memoryless nodes are
a bit strange given that the NUMA paradigm is to have NUMA nodes (meaning
memory) with processors. MEMORYLESS nodes means that we have a fake NUMA
node without memory but just processors. Not very efficient. Not sure why
people use these configurations.

> I don't know, because I'm not expert on NUMA system :)
> At first glance, fakenuma can't be used for testing
> CONFIG_HAVE_MEMORYLESS_NODES. Maybe some modification is needed.

Well yeah. You'd have to do some mods to enable that testing.