On Jul 26, 2006, at 5:07 PM, Mauricio Felga Gobbi wrote:
Newbie question:
How is the message passing of Open-MPI implemented when I have
say 4 nodes with 4 processors (SMP) each, nodes connected by a gigabit
ethernet ?... in other words, how does it manage SMP nodes when I
want to use all CPUs, but each with its own process. Does it take
any advantage of the SMP at each node?
Someone can give you a more complete/correct answer but I'll give you
my understanding.
All communication in OpenMPI is handled via the MCA module (term?)
self - process communicating with itself
sm - ... via shared memory to other processes
tcp - ... via tcp
openib - ... via Infiniband OpenIB stack
gm & mx - ... via Myrinet GM/MX
mvapi - ... via Infiniband Mellanox Verbs
If you launch your process so that four processes are on a node then
those would use shared memory to communicate.
Michael
