Are you saying t(single-process execution) < t(4-process execution)
for identical problems on each (same total amount of data)?
There's rarely a speedup in such a case-- processing the same
amount of data while shipping some fraction of it over
a slow network between processing steps is almost certain to be slower.
Where things get interesting (and encouraging) is if you increase
the total data being processed (hold data quantity per node constant).
On Thu, Jun 07, 2007 at 08:24:03PM -0400, Aaron Thompson wrote:
> Does anyone have experience using DL POLY with OpenMPI? I've gotten
> it to compile, but when I run a simulation using mpirun with two dual-
> processor machines, it runs a little *slower* than on one CPU on one
> machine! Yet the program is running two instances on each node. Any
> ideas? The test programs included with OpenMPI show that it is
> running correctly across multiple nodes.
> Sorry if this is a little off-topic, I wasn't able to find help on
> the official DL POLY mailing list.
> Thank you!
> Aaron Thompson
> Vanderbilt University
> users mailing list