1 /* Copyright (c) 2013-2021. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "../colls_private.hpp"
7 #include "smpi_status.hpp"
9 /*****************************************************************************
11 Copyright (c) 2006, Ahmad Faraj & Xin Yuan,
14 Redistribution and use in source and binary forms, with or without
15 modification, are permitted provided that the following conditions are met:
17 * Redistributions of source code must retain the above copyright notice,
18 this list of conditions and the following disclaimer.
20 * Redistributions in binary form must reproduce the above copyright notice,
21 this list of conditions and the following disclaimer in the documentation
22 and/or other materials provided with the distribution.
24 * Neither the name of the Florida State University nor the names of its
25 contributors may be used to endorse or promote products derived from this
26 software without specific prior written permission.
28 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
29 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
30 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
31 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
32 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
33 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
34 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
35 ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
37 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *************************************************************************
40 * Any results obtained from executing this software require the *
41 * acknowledgment and citation of the software and its owners. *
42 * The full citation is given below: *
44 * A. Faraj and X. Yuan. "Automatic Generation and Tuning of MPI *
45 * Collective Communication Routines." The 19th ACM International *
46 * Conference on Supercomputing (ICS), Cambridge, Massachusetts, *
48 *************************************************************************
50 *****************************************************************************/
52 /*****************************************************************************
54 * Function: bcast_scatter_LR_allgather
59 buff: send input buffer
60 count: number of elements to send
61 data_type: data type of elements being sent
65 * Descrp: broadcasts using a scatter followed by LR allgather.
67 * Author: MPIH / modified by Ahmad Faraj
69 ****************************************************************************/
72 int bcast__scatter_LR_allgather(void *buff, int count,
73 MPI_Datatype data_type, int root,
78 int i, src, dst, rank, num_procs;
79 int mask, relative_rank, curr_size, recv_size, send_size, nbytes;
80 int scatter_size, left, right, next_src;
81 int tag = COLL_TAG_BCAST;
84 num_procs = comm->size();
85 extent = data_type->get_extent();
88 nbytes = extent * count;
89 scatter_size = (nbytes + num_procs - 1) / num_procs; // ceiling division
90 curr_size = (rank == root) ? nbytes : 0; // root starts with all the data
91 relative_rank = (rank >= root) ? rank - root : rank - root + num_procs;
94 while (mask < num_procs) {
95 if (relative_rank & mask) {
99 recv_size = nbytes - relative_rank * scatter_size;
100 // recv_size is larger than what might actually be sent by the
101 // sender. We don't need compute the exact value because MPI
102 // allows you to post a larger recv.
104 curr_size = 0; // this process doesn't receive any data
105 // because of uneven division
107 Request::recv((char *) buff + relative_rank * scatter_size, recv_size,
108 MPI_BYTE, src, tag, comm, &status);
109 curr_size = Status::get_count(&status, MPI_BYTE);
116 // This process is responsible for all processes that have bits
117 // set from the LSB up to (but not including) mask. Because of
118 // the "not including", we start by shifting mask back down
123 if (relative_rank + mask < num_procs) {
124 send_size = curr_size - scatter_size * mask;
125 // mask is also the size of this process's subtree
129 if (dst >= num_procs)
131 Request::send((char *) buff + scatter_size * (relative_rank + mask),
132 send_size, MPI_BYTE, dst, tag, comm);
134 curr_size -= send_size;
140 // done scatter now do allgather
141 int* recv_counts = new int[num_procs];
142 int* disps = new int[num_procs];
144 for (i = 0; i < num_procs; i++) {
145 recv_counts[i] = nbytes - i * scatter_size;
146 if (recv_counts[i] > scatter_size)
147 recv_counts[i] = scatter_size;
148 if (recv_counts[i] < 0)
153 for (i = 1; i < num_procs; i++)
154 disps[i] = disps[i - 1] + recv_counts[i - 1];
156 left = (num_procs + rank - 1) % num_procs;
157 right = (rank + 1) % num_procs;
162 for (i = 1; i < num_procs; i++) {
163 Request::sendrecv((char *) buff + disps[(src - root + num_procs) % num_procs],
164 recv_counts[(src - root + num_procs) % num_procs],
165 MPI_BYTE, right, tag,
167 disps[(next_src - root + num_procs) % num_procs],
168 recv_counts[(next_src - root + num_procs) % num_procs],
169 MPI_BYTE, left, tag, comm, &status);
171 next_src = (num_procs + next_src - 1) % num_procs;
174 delete[] recv_counts;