1 /* Copyright (c) 2013-2021. 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_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 ****************************************************************************/
32 alltoall__ring_mpi_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, MPI_Comm comm)
38 MPI_Aint send_chunk, recv_chunk;
39 int i, src, dst, rank, num_procs;
40 int tag = COLL_TAG_ALLTOALL;
42 char *send_ptr = (char *) send_buff;
43 char *recv_ptr = (char *) recv_buff;
46 num_procs = comm->size();
47 send_chunk = send_type->get_extent();
48 recv_chunk = recv_type->get_extent();
50 send_chunk *= send_count;
51 recv_chunk *= recv_count;
53 for (i = 0; i < num_procs; i++) {
54 src = (rank - i + num_procs) % num_procs;
55 dst = (rank + i) % num_procs;
58 Request::sendrecv(send_ptr + dst * send_chunk, send_count, send_type, dst,
59 tag, recv_ptr + src * recv_chunk, recv_count, recv_type,