On May 29, 2007, at 12:25 PM, smai...@ksu.edu wrote:
I am doing a research on parallel computing on shared memory with
NUMA architecture. The system is a 4 node AMD opteron with each node
being a dual-core. I am testing an OpenMPI program with MPI-nodes <=
MAX cores available on system (in my case 4*2=8). Can someone tell me
whether:
a) In such cases (where MPI-nodes<=MAX cores on shared-memory),
OpenMPI
implements MPI-nodes as processes or threads? If yes, then how can it
be determined at run-time? I am wondering because processes have more
overhead than light-weight threads.
In Open MPI, different MPI ranks are always different processes.
This is what users expect, and I'd be hesitant to change that for the
over-subscription case.
Brian
