1 #include "colls_private.h"
2 /*****************************************************************************
4 * Function: alltoall_ring
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 in P - 1 steps. In step i, node j - i -> j -> j + i.
21 ****************************************************************************/
23 smpi_coll_tuned_alltoall_ring(void *send_buff, int send_count,
24 MPI_Datatype send_type, void *recv_buff,
25 int recv_count, MPI_Datatype recv_type,
29 MPI_Aint send_chunk, recv_chunk;
30 int i, src, dst, rank, num_procs;
31 int tag = COLL_TAG_ALLTOALL;
33 char *send_ptr = (char *) send_buff;
34 char *recv_ptr = (char *) recv_buff;
36 rank = smpi_comm_rank(comm);
37 num_procs = smpi_comm_size(comm);
38 send_chunk = smpi_datatype_get_extent(send_type);
39 recv_chunk = smpi_datatype_get_extent(recv_type);
41 send_chunk *= send_count;
42 recv_chunk *= recv_count;
44 for (i = 0; i < num_procs; i++) {
45 src = (rank - i + num_procs) % num_procs;
46 dst = (rank + i) % num_procs;
48 smpi_mpi_sendrecv(send_ptr + dst * send_chunk, send_count, send_type, dst,
49 tag, recv_ptr + src * recv_chunk, recv_count, recv_type,