On Feb 13, 2013, at 10:59 AM CST, m srini wrote:

I have a small doubt regarding the patterns that the collective calls use. Do they still use the patterns mentioned in the paper "OPTIMIZING MPI COLLECTIVE CALLS" by Rajeev Thakur ? If not please help me in understanding the collective call patterns.

Most of those same patterns/algorithms are still in use. The most accurate way to determine what is used is to examine the source, particularly the sources in the "src/mpi/coll" directory: http://git.mpich.org/mpich.git/tree/HEAD:/src/mpi/coll -Dave