1 /* Copyright (c) 2013-2020. 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.hpp"
8 /*****************************************************************************
10 * Function: alltoall_pair_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 when P is power of two. In each phase of P - 1
24 phases, nodes in pair communicate their data. MPI barriers are
25 inserted between each two phases.
29 ****************************************************************************/
33 alltoall__pair_mpi_barrier(const void *send_buff, int send_count,
34 MPI_Datatype send_type,
35 void *recv_buff, int recv_count,
36 MPI_Datatype recv_type, MPI_Comm comm)
39 MPI_Aint send_chunk, recv_chunk;
40 int i, src, dst, rank, num_procs;
41 int tag = COLL_TAG_ALLTOALL;
42 char *send_ptr = (char *) send_buff;
43 char *recv_ptr = (char *) recv_buff;
46 num_procs = comm->size();
48 if((num_procs&(num_procs-1)))
49 throw std::invalid_argument("alltoall pair algorithm can't be used with non power of two number of processes!");
51 send_chunk = send_type->get_extent();
52 recv_chunk = recv_type->get_extent();
54 send_chunk *= send_count;
55 recv_chunk *= recv_count;
57 for (i = 0; i < num_procs; i++) {
60 Request::sendrecv(send_ptr + dst * send_chunk, send_count, send_type, dst,
61 tag, recv_ptr + src * recv_chunk, recv_count, recv_type,