[OMPI users] Loopback Communication

[Elvedin Trnjanin]

I'm using a "ping pong" program to approximate bandwidth and latency of 
various messages sizes and I notice when doing various transfers (eg. 
async) that the maximum bandwidth isn't the system's maximum bandwidth. 
I've looked through the FAQ and I haven't noticed this being covered but 
how does OpenMPI handle loopback communication? Is it still over a 
network interconnect or some sort of shared memory copy?

- Elvedin