On Nov 15, 2009, at 6:07 AM, Charles Salvia wrote:
With using TCP with OpenMPI 1.3.3, how many sockets does each process open per peer-process? Does each process open a single socket to connect to each peer-process, or does it use TWO sockets, one for sending, one for receiving?
There are multiple flavors of TCP communication potentially happening in each Open MPI process.
We use TCP sockets for control signals between mpirun and the MPI process, for example. In the OMPI 1.3 series, this is a local TCP socket to the "orted" helper daemon process that OMPI launches in the background.
Additionally, if you're using TCP and shared memory for MPI communications (i.e., the TCP BTL module), Open MPI will lazily open 1 TCP socket to each non-local peer process which which you exchange MPI communications.
-- Jeff Squyres jsquy...@cisco.com
