On Fri, Dec 08, 2006 at 04:11:04PM +0530, krishna chaitanya wrote: > I learnt from a reliable source that MPI uses the services > provided by TCP/IP or infiniband.
Did you hear that from a whistle-blower? > Suppose that there is a bottle-neck in > the TCP/IP layer itself, how will optimization of MPI calls really help? Bottleneck is usually a fuzzy term. Collective calls basically means for example that you tell MPI: "send this to all nodes" instead of for(i=0;i<number_of_nodes;i++) "send this to node i" Therefore you don't have serialization of the tasks and the MPI layer could do optmizations. For example the connection network could have a way to broadcast or at least sending could be interleaved. Christian Leber -- http://rettetdieti.vde-uni-mannheim.de/
