MPI_Datatype dtype, MPI_Op op, MPI_Comm comm)
{
int nprocs, rank, tag = COLL_TAG_ALLREDUCE;
int mask, dst, pof2, newrank, rem, newdst;
MPI_Aint extent, lb;
MPI_Status status;
MPI_Datatype dtype, MPI_Op op, MPI_Comm comm)
{
int nprocs, rank, tag = COLL_TAG_ALLREDUCE;
int mask, dst, pof2, newrank, rem, newdst;
MPI_Aint extent, lb;
MPI_Status status;