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"
13 // now only work with power of two processes
16 allgather__rhv(const void *sbuf, int send_count,
17 MPI_Datatype send_type, void *rbuf,
18 int recv_count, MPI_Datatype recv_type,
22 MPI_Aint s_extent, r_extent;
24 // local int variables
25 int i, dst, send_base_offset, recv_base_offset, send_chunk, recv_chunk,
26 send_offset, recv_offset;
27 int tag = COLL_TAG_ALLGATHER;
31 // get size of the communicator, followed by rank
32 unsigned int num_procs = comm->size();
34 if((num_procs&(num_procs-1)))
35 throw std::invalid_argument("allgather rhv algorithm can't be used with non power of two number of processes!");
37 unsigned int rank = comm->rank();
39 // get size of single element's type for send buffer and recv buffer
40 s_extent = send_type->get_extent();
41 r_extent = recv_type->get_extent();
43 // multiply size of each element by number of elements to send or recv
44 send_chunk = s_extent * send_count;
45 recv_chunk = r_extent * recv_count;
47 if (send_chunk != recv_chunk) {
48 XBT_WARN("MPI_allgather_rhv use default MPI_allgather.");
49 allgather__default(sbuf, send_count, send_type, rbuf, recv_count,
54 // compute starting offset location to perform local copy
55 int size = num_procs / 2;
58 while (mask < num_procs) {
66 // printf("node %d base_offset %d\n",rank,base_offset);
68 //perform a remote copy
71 Request::sendrecv(sbuf, send_count, send_type, dst, tag,
72 (char *)rbuf + base_offset * recv_chunk, recv_count, recv_type, dst, tag,
79 curr_count = recv_count;
81 // destination pair for both send and recv
85 send_base_offset = base_offset;
87 recv_base_offset = base_offset - i;
90 recv_base_offset = base_offset + i;
92 send_offset = send_base_offset * recv_chunk;
93 recv_offset = recv_base_offset * recv_chunk;
95 // printf("node %d send to %d in phase %d s_offset = %d r_offset = %d count = %d\n",rank,dst,phase, send_base_offset, recv_base_offset, curr_count);
97 Request::sendrecv((char*)rbuf + send_offset, curr_count, recv_type, dst, tag, (char*)rbuf + recv_offset, curr_count,
98 recv_type, dst, tag, comm, &status);