On May 12, 2010, at 3:01 PM, Fernando Lemos wrote: > Please correct me if I'm wrong, but I believe OpenMPI sends > stdin/stdout from the other ranks back to rank 0 so that the output is > displayed as the stdin of mpirun and the other way around with > stdout/stderr. Otherwise it wouldn't be possible to even see the > output from the other ranks. I guess that could make things slower.
Correct, OMPI does this. The original question asked if we overrode getc(); we do not. Open MPI sends stdin and receives stdout/stderr via pipes to MPI processes. The phrasing of the original question also led me to believe that the program was being run without mpirun, but that could be a bad assumption on my part. Another relevant data point here would be exactly what "4x slower" means. -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
