[ofiwg] job key support discussion

[Hefty, Sean]

Moving an issue discussion to the mailing list for broader discussion.

There is an open issue around adding job key support to the libfabric APIs:

https://github.com/ofiwg/libfabric/issues/2529

One of the central points of the discussion is to determine which API object(s) to associate with the authorization key(s).  So far, there seems to be agreement that we don't want the job key to be specified with each data transfer.  Removing that option:

Endpoint - Each EP can be assigned a different key.  This allows EPs used to communicate with different sets of peers to share CQs, AV, counters, and other domain resources.

Domain - This isolates resources for a given set of peers into different domains.  Domain resources (CQs, counters, AV, etc.) would need to be allocated for each key that is used.

With the domain option, memory regions are associated with specific keys.  With the endpoint option, an additional API is needed to associate memory regions with a key.

- Sean