On Dec 9, 2008, at 9:49 PM, Brock Palen wrote:
Is OpenMPI using Multicast for things like MPI_Bcast() ?
Not today. There have been some experiments with it, but nothing yet.
Some simple tests of really old versions (1.0.2) showed binary tree
type performance, while latter versions gave me the same run time no
matter how many CPU's I used.
Thus this lead me to believe that something like multicast is in
use. Is it?
That's an interesting result. It should depend on factors such as the
number of MPI processes you use, the size of the message, the layout
on the hosts/network, etc.
--
Jeff Squyres
Cisco Systems
