1 /* Copyright (c) 2013-2023. 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_light_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 exchanges data
24 with node i ^ j. Light barriers are inserted between
25 communications in different phases.
29 ****************************************************************************/
30 namespace simgrid::smpi {
32 alltoall__pair_light_barrier(const void *send_buff, int send_count,
33 MPI_Datatype send_type,
34 void *recv_buff, int recv_count,
35 MPI_Datatype recv_type,
38 MPI_Aint send_chunk, recv_chunk;
40 int i, src, dst, rank, num_procs, next_partner;
41 int tag = COLL_TAG_ALLTOALL; /*, failure = 0; */
43 char send_sync = 'a', recv_sync = 'b';
44 char *send_ptr = (char *) send_buff;
45 char *recv_ptr = (char *) recv_buff;
48 num_procs = comm->size();
50 if((num_procs&(num_procs-1)))
51 throw std::invalid_argument("alltoall pair algorithm can't be used with non power of two number of processes!");
53 send_chunk = send_type->get_extent();
54 recv_chunk = recv_type->get_extent();
56 send_chunk *= send_count;
57 recv_chunk *= recv_count;
59 Request::sendrecv(send_ptr + rank * send_chunk, send_count, send_type, rank, tag,
60 recv_ptr + rank * recv_chunk, recv_count, recv_type, rank, tag,
63 for (i = 1; i < num_procs; i++) {
66 Request::sendrecv(send_ptr + dst * send_chunk, send_count, send_type,
67 dst, tag, recv_ptr + src * recv_chunk, recv_count,
68 recv_type, src, tag, comm, &s);
70 if ((i + 1) < num_procs) {
71 next_partner = rank ^ (i + 1);
72 Request::sendrecv(&send_sync, 1, MPI_CHAR, next_partner, tag,
73 &recv_sync, 1, MPI_CHAR, next_partner, tag, comm, &s);
78 } // namespace simgrid::smpi