2 /*****************************************************************************
4 * Function: alltoall_pair_mpi_barrier
9 send_buff: send input buffer
10 send_count: number of elements to send
11 send_type: data type of elements being sent
12 recv_buff: receive output buffer
13 recv_count: number of elements to received
14 recv_type: data type of elements being received
17 * Descrp: Function works when P is power of two. In each phase of P - 1
18 phases, nodes in pair communicate their data. MPI barriers are
19 inserted between each two phases.
23 ****************************************************************************/
25 smpi_coll_tuned_alltoall_pair_mpi_barrier(void *send_buff, int send_count,
26 MPI_Datatype send_type,
27 void *recv_buff, int recv_count,
28 MPI_Datatype recv_type, MPI_Comm comm)
31 MPI_Aint send_chunk, recv_chunk;
32 int i, src, dst, rank, num_procs;
34 char *send_ptr = (char *) send_buff;
35 char *recv_ptr = (char *) recv_buff;
37 MPI_Comm_rank(comm, &rank);
38 MPI_Comm_size(comm, &num_procs);
39 MPI_Type_extent(send_type, &send_chunk);
40 MPI_Type_extent(recv_type, &recv_chunk);
42 send_chunk *= send_count;
43 recv_chunk *= recv_count;
45 for (i = 0; i < num_procs; i++) {
48 MPI_Sendrecv(send_ptr + dst * send_chunk, send_count, send_type, dst,
49 tag, recv_ptr + src * recv_chunk, recv_count, recv_type,