On 4/6/2010 2:53 PM, Jeff Squyres wrote: > > Try NetPIPE -- it has both MPI communication benchmarking and TCP > benchmarking. Then you can see if there is a noticable difference between > TCP and MPI (there shouldn't be). There's also a "memcpy" mode in netpipe, > but it's not quite the same thing as shared memory message passing. >
Using netpipe and comparing tcp and mpi communication I get the following results: TCP is much faster than MPI, approx. by factor 12 e.g a packet size of 4096 bytes deliveres in 97.11 usec with NPtcp and 15338.98 usec with NPmpi or packet size 262kb 0.05268801 sec NPtcp 0.00254560 sec NPmpi Further our benchmark started with "--mca btl tcp,self" runs with short communication times, even using kernel 2.6.33.1 Is there a way to see what type of communication is actually selected? Can anybody imagine why shared memory leads to these problems? Kernel configuration? Thanks, Jeff, for insisting upon testing network performance. Thanks all others, too ;-) oli -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.
