show -topology output when running the processor are in SNC mode

[bgoglin]

Hello

On a dual-socket machine in SubNUMA-Cluster mode, we get 4 DDR NUMA nodes. I configured the NVDIMMs with ipmctl create -goal MemoryMode=0 and got 2 regions (one per socket).

Running "ipmctl show -a -topology" says that NVDIMMs are either located on Socket 0 or on Socket 1, which is correct. However, the documentation (https://github.com/intel/ipmctl/blob/master/Documentation/ipmctl/DIMM_Discovery/ipmctl-show-topology.txt) also talks about NUMA nodes:

SocketID::
  The processor socket identifier (i.e., NUMA node) where the DIMM is installed.

If -topology were to report NUMA nodes on my machine, it should report 0&1 and 2&3 instead of 0 and 1 respectively.

That said, I am not sure if my setup is something normal. Whenever configuring the processor in SNC-mode, should we create one region per SNC instead of one per socket? If so, how are we supposed to do this? Could ipmctl be able to report the correct topology in that case? (region0&1 are close to socket 0, region2&2 are close to socket 1, but regionX is close to NUMA node X).

Thanks
Brice

[kellycouch]

The comment when indicates socket is equivalent to NUMA node is incorrect. This will be removed in future documentation update.
AppDirect capacity shall always result in an interleave set (region) across each DCPMM in each socket. The exception is if requesting x1 (non-interleaved) regions.