Is there a rule of thumb for when it is best to contact N workers with
MPI_Bcast vs. when it is best to use a loop which cycles N times and
moves the same information with MPI_Send to one worker at a time?
For that matter, other than the coding semantics, is there any real
difference between the two approaches? That is, does MPI_Bcast really
broadcast, daisy chain, or use other similar methods to reduce bandwidth
use when distributing its message, or does it just go ahead and run
MPI_Send in a loop anyway, but hide the details from the programmer?
Manager, Sequence Analysis Facility, Biology Division, Caltech