2 /*****************************************************************************
4 * Function: alltoall_pair
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.
22 ****************************************************************************/
24 smpi_coll_tuned_alltoall_pair_one_barrier(void * send_buff, int send_count, MPI_Datatype send_type,
25 void * recv_buff, int recv_count, MPI_Datatype recv_type,
29 MPI_Aint send_chunk, recv_chunk;
31 int i, src, dst, rank, num_procs;
32 int tag = 1, success = 1; /*, failure = 0, pof2 = 1; */
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;
46 for (i = 0; i < num_procs; i++)
49 MPI_Sendrecv(send_ptr + dst * send_chunk, send_count, send_type, dst,
50 tag, recv_ptr + src * recv_chunk, recv_count, recv_type,