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_pair
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 when P is power of two. In each phase of P - 1
24 phases, nodes in pair communicate their data.
28 ****************************************************************************/
30 smpi_coll_tuned_alltoall_pair_one_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;
38 int i, src, dst, rank, num_procs;
39 int tag = COLL_TAG_ALLTOALL;
41 char *send_ptr = (char *) send_buff;
42 char *recv_ptr = (char *) recv_buff;
44 rank = smpi_comm_rank(comm);
45 num_procs = smpi_comm_size(comm);
47 if((num_procs&(num_procs-1)))
48 THROWF(arg_error,0, "alltoall pair algorithm can't be used with non power of two number of processes ! ");
50 send_chunk = smpi_datatype_get_extent(send_type);
51 recv_chunk = smpi_datatype_get_extent(recv_type);
53 send_chunk *= send_count;
54 recv_chunk *= recv_count;
56 mpi_coll_barrier_fun(comm);
57 for (i = 0; i < num_procs; i++) {
59 smpi_mpi_sendrecv(send_ptr + dst * send_chunk, send_count, send_type, dst,
60 tag, recv_ptr + src * recv_chunk, recv_count, recv_type,