Current SGI Altix systems have a NUMAlink domain size of 1024
compute nodes and are fully cache coherent up to 256 compute
nodes (compute nodes are even-numbered).  Systems larger than
256 nodes are partitioned into multiple cache coherent systems.
This patch exports a partition's coherence id to users via the
/proc/sgi_sn/coherence_id file.
Signed-off-by: Dean Roe <roe@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>