Eugene Loh wrote:
> I'm no expert, but I think it's something like this:
> 1) If the messages are short, they're sent over to the receiver. If the
> receiver does not expect them (no MPI_Irecv posted), it buffers them up.
> 2) If the messages are long, only a little bit is sent over to the
> receiver. The receiver will take in that little bit, but until an
> MPI_Irecv is posted it will not signal the sender that any more can be sent.
> Are these messages being sent over TCP between nodes? How long are they?
Each message is 2500 bytes, as I mentioned previously. In fact, each
message is composed of one hundred 25-byte operations that have been
queued up at the application level and sent with a single MPI_Send. It
would depend on the nature of the application of course, but is there
any reason to believe that 100 individual MPI_Send would be any
faster? Or is there a better way to queue up messages for a batch