1 /* Copyright (c) 2013-2019. 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
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.
27 ****************************************************************************/
30 int Coll_alltoallv_ring::alltoallv(const void* send_buff, const int* send_counts, const int* send_disps, MPI_Datatype send_type,
31 void* recv_buff, const int* recv_counts, const int* recv_disps, MPI_Datatype recv_type,
35 MPI_Aint send_chunk, recv_chunk;
36 int i, src, dst, rank, num_procs;
37 int tag = COLL_TAG_ALLTOALLV;
39 char *send_ptr = (char *) send_buff;
40 char *recv_ptr = (char *) recv_buff;
43 num_procs = comm->size();
44 send_chunk = send_type->get_extent();
45 recv_chunk = recv_type->get_extent();
46 int pof2 = ((num_procs != 0) && ((num_procs & (~num_procs + 1)) == num_procs));
47 for (i = 0; i < num_procs; i++) {
50 /* use exclusive-or algorithm */
53 src = (rank - i + num_procs) % num_procs;
54 dst = (rank + i) % num_procs;
57 Request::sendrecv(send_ptr + send_disps[dst] * send_chunk, send_counts[dst], send_type, dst,
58 tag, recv_ptr + recv_disps[src] * recv_chunk, recv_counts[src], recv_type,