MPI_Barrier

Blocks until all process have reached this routine.

Synopsis

#include "mpi.h"
int MPI_Barrier (MPI_Comm comm )

Input Parameters

  comm  communicator (handle) 

Notes

Blocks the caller until all group members have called it; the call returns at any process only after all group members have entered the call.

Algorithm

If the underlying device cannot do better, a tree-like or combine algorithm is used to broadcast a message wto all members of the communicator. We can modifiy this to use "blocks" at a later time (see mpich/MPI_Bcast).