On Nov 21, 2005, at 3:46 PM, Angel Tsankov wrote:
>> Yes, message size definitely affects communication time, regardless
>> of the communication media (i.e., even with shared memory).
>
> What about communication startup time? Does it depend on the size of
> data if Ehternet is used?
Do you mean startup in terms of MPI_INIT, or startup in terms of every
communication?
The MPI_INIT startup times are going to be linear based on the number
of processes involved. Startup in terms of every communication is
fairly constant. The latency of ethernet-based communication is going
to be much higher than for shared memory-based communication.
--
{+} Jeff Squyres
{+} The Open MPI Project
{+} http://www.open-mpi.org/
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