int MPI_Barrier(MPI_Comm comm)The only argument of MPI_Barrier is the communicator that defines the group of processes that are synchronized. The call to MPI_Barrier returns only after all the processes in the group have called this function.
int MPI_Bcast(void *buf, int count, MPI_Datatype datatype, int source, MPI_Comm comm)MPI_Bcast sends the data stored in the buffer buf of process source to all the other processes in the group. The data received by each process is stored in the buffer buf. The data that is broadcast consist of count entries of type datatype.