/* (C) 2001 by Argonne National Laboratory. See COPYRIGHT in top-level directory. */ #include <stdio.h> #include <string.h> #include "mpi.h" int main( int argc, char *argv[] ) { int comm_rank, comm_size, comm_neighbor; int world_rank, world_size, world_neighbor; int icolor, namelen, ibuffer; char processor_name[MPI_MAX_PROCESSOR_NAME]; MPI_Comm splited_comm, duped_comm, inter_comm, *comm_ptr; MPI_Request world_request, comm_request; MPI_Status world_status, comm_status; MPI_Init( &argc, &argv ); MPI_Comm_size( MPI_COMM_WORLD, &world_size ); MPI_Comm_rank( MPI_COMM_WORLD, &world_rank ); MPI_Get_processor_name( processor_name, &namelen ); fprintf( stdout, "world_rank %d on %s\n", world_rank, processor_name ); fflush( stdout ); if ( world_rank == world_size - 1 ) world_neighbor = 0; else world_neighbor = world_rank + 1; MPI_Irecv( &ibuffer, 1, MPI_INT, MPI_ANY_SOURCE, 99, MPI_COMM_WORLD, &world_request ); MPI_Send( &world_rank, 1, MPI_INT, world_neighbor, 99, MPI_COMM_WORLD ); MPI_Wait( &world_request, &world_status ); /* Split all processes into 2 separate intracommunicators */ icolor = world_rank % 2; MPI_Comm_split( MPI_COMM_WORLD, icolor, world_rank, &splited_comm ); /* Put in a Comm_dup so local comm ID is different in 2 splited comm */ if ( icolor == 0 ) { MPI_Comm_dup( splited_comm, &duped_comm ); comm_ptr = &duped_comm; } else comm_ptr = &splited_comm; MPI_Comm_size( *comm_ptr, &comm_size ); MPI_Comm_rank( *comm_ptr, &comm_rank ); if ( comm_rank == comm_size - 1 ) comm_neighbor = 0; else comm_neighbor = comm_rank + 1; MPI_Irecv( &ibuffer, 1, MPI_INT, MPI_ANY_SOURCE, 999, *comm_ptr, &comm_request ); MPI_Send( &comm_rank, 1, MPI_INT, comm_neighbor, 999, *comm_ptr ); MPI_Wait( &comm_request, &comm_status ); /* Form an intercomm between the 2 splited intracomm's */ if ( icolor == 0 ) MPI_Intercomm_create( *comm_ptr, 0, MPI_COMM_WORLD, 1, 9090, &inter_comm ); else MPI_Intercomm_create( *comm_ptr, 0, MPI_COMM_WORLD, 0, 9090, &inter_comm ); if ( comm_rank == 0 ) { MPI_Irecv( &ibuffer, 1, MPI_INT, 0, 9999, inter_comm, &comm_request ); MPI_Send( &comm_rank, 1, MPI_INT, 0, 9999, inter_comm ); MPI_Wait( &comm_request, &comm_status ); } /* Free all communicators created */ MPI_Comm_free( &inter_comm ); if ( icolor == 0 ) MPI_Comm_free( &duped_comm ); MPI_Comm_free( &splited_comm ); MPI_Finalize(); return( 0 ); }