[OMPI users] Collective operations and synchronization

[Shaun Jackman]

I've just read in the Open MPI documentation [1] that collective 
operations, such as MPI_Allreduce, may synchronize, but do not 
necessarily synchronize. My algorithm requires a collective operation 
and synchronization; is there a better (more efficient?) method than 
simply calling MPI_Allreduce followed by MPI_Barrier?

Thanks,
Shaun
[1] http://www.mpi-forum.org/docs/mpi21-report-bw/node85.htm