[libfabric-users] Multiple ranks/instances on the same node

[Hefty, Sean]

> If I have multiple processes (ranks) on the same node, and they send messages to each
> other. Does libfabric auto-magically do the right thing and use some kind of shared
> memory for them. If not - can this be enabled by using one of the shared memory
> providers (in conjunction with the gni provider for example) - and if this is the case,
> does one need to use a special endpoint to communicate within node - or will that be
> handled automatically.

The answer is provider specific.  For example, psm/psm2 will use shared memory.  Other providers will not. (I'm not sure about gni).  A generic solution is unlikely.  Shared memory support must be integrated on a provider by provider basis to support proper tag matching semantics.  Ideally, at least rxm and rxd would integrate shared memory support.  There's just a developer resource shortage to make that happen.

- Sean