1 /* Copyright (c) 2013-2018. 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"
14 // Allgather-Non-Topoloty-Scecific-Logical-Ring algorithm
16 Coll_allgather_NTSLR::allgather(void *sbuf, int scount, MPI_Datatype stype,
17 void *rbuf, int rcount, MPI_Datatype rtype,
20 MPI_Aint rextent, sextent;
22 int i, to, from, rank, size;
23 int send_offset, recv_offset;
24 int tag = COLL_TAG_ALLGATHER;
28 rextent = rtype->get_extent();
29 sextent = stype->get_extent();
31 // irregular case use default MPI fucntions
32 if (scount * sextent != rcount * rextent) {
33 XBT_WARN("MPI_allgather_NTSLR use default MPI_allgather.");
34 Coll_allgather_default::allgather(sbuf, scount, stype, rbuf, rcount, rtype, comm);
39 to = (rank + 1) % size;
40 from = (rank + size - 1) % size;
42 //copy a single segment from sbuf to rbuf
43 send_offset = rank * scount * sextent;
45 Request::sendrecv(sbuf, scount, stype, rank, tag,
46 (char *)rbuf + send_offset, rcount, rtype, rank, tag,
50 //start sending logical ring message
51 int increment = scount * sextent;
52 for (i = 0; i < size - 1; i++) {
53 send_offset = ((rank - i + size) % size) * increment;
54 recv_offset = ((rank - i - 1 + size) % size) * increment;
55 Request::sendrecv((char *) rbuf + send_offset, scount, stype, to, tag + i,
56 (char *) rbuf + recv_offset, rcount, rtype, from, tag + i,