1 /* Copyright (c) 2013-2014. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
7 #include "colls_private.h"
8 /*****************************************************************************
10 * Function: alltoall_ring_mpi_barrier
15 send_buff: send input buffer
16 send_count: number of elements to send
17 send_type: data type of elements being sent
18 recv_buff: receive output buffer
19 recv_count: number of elements to received
20 recv_type: data type of elements being received
23 * Descrp: Function works in P - 1 steps. In step i, node j - i -> j -> j + i.
24 MPI barriers are added between each two phases.
28 ****************************************************************************/
30 smpi_coll_tuned_alltoall_ring_mpi_barrier(void *send_buff, int send_count,
31 MPI_Datatype send_type,
32 void *recv_buff, int recv_count,
33 MPI_Datatype recv_type, MPI_Comm comm)
36 MPI_Aint send_chunk, recv_chunk;
37 int i, src, dst, rank, num_procs;
38 int tag = COLL_TAG_ALLTOALL;
40 char *send_ptr = (char *) send_buff;
41 char *recv_ptr = (char *) recv_buff;
43 rank = smpi_comm_rank(comm);
44 num_procs = smpi_comm_size(comm);
45 send_chunk = smpi_datatype_get_extent(send_type);
46 recv_chunk = smpi_datatype_get_extent(recv_type);
48 send_chunk *= send_count;
49 recv_chunk *= recv_count;
51 for (i = 0; i < num_procs; i++) {
52 src = (rank - i + num_procs) % num_procs;
53 dst = (rank + i) % num_procs;
55 mpi_coll_barrier_fun(comm);
56 smpi_mpi_sendrecv(send_ptr + dst * send_chunk, send_count, send_type, dst,
57 tag, recv_ptr + src * recv_chunk, recv_count, recv_type,