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 #include "smpi_status.hpp"
10 /*****************************************************************************
12 * Function: alltoall_rdb
17 send_buff: send input buffer
18 send_count: number of elements to send
19 send_type: data type of elements being sent
20 recv_buff: receive output buffer
21 recv_count: number of elements to received
22 recv_type: data type of elements being received
25 * Descrp: Function realizes the allgather operation using the recursive
28 * Author: MPICH / slightly modified by Ahmad Faraj.
30 ****************************************************************************/
33 int alltoall__rdb(const void *send_buff, int send_count,
34 MPI_Datatype send_type,
35 void *recv_buff, int recv_count,
36 MPI_Datatype recv_type, MPI_Comm comm)
40 MPI_Aint send_increment, recv_increment, extent;
42 int dst_tree_root, rank_tree_root, send_offset, recv_offset;
43 int rank, num_procs, j, k, dst, curr_size, max_size;
44 int last_recv_count = 0, tmp_mask, tree_root, num_procs_completed;
45 int tag = COLL_TAG_ALLTOALL, mask = 1, i = 0;
47 char *send_ptr = (char *) send_buff;
48 char *recv_ptr = (char *) recv_buff;
50 num_procs = comm->size();
52 send_increment = send_type->get_extent();
53 recv_increment = recv_type->get_extent();
54 extent = recv_type->get_extent();
56 send_increment *= (send_count * num_procs);
57 recv_increment *= (recv_count * num_procs);
59 max_size = num_procs * recv_increment;
61 unsigned char* tmp_buff = smpi_get_tmp_sendbuffer(max_size);
63 curr_size = send_count * num_procs;
65 Request::sendrecv(send_ptr, curr_size, send_type, rank, tag,
66 tmp_buff + (rank * recv_increment),
67 curr_size, recv_type, rank, tag, comm, &status);
69 while (mask < num_procs) {
71 dst_tree_root = dst >> i;
73 rank_tree_root = rank >> i;
75 send_offset = rank_tree_root * send_increment;
76 recv_offset = dst_tree_root * recv_increment;
78 if (dst < num_procs) {
79 Request::sendrecv(tmp_buff + send_offset, curr_size, send_type, dst, tag,
80 tmp_buff + recv_offset, mask * recv_count * num_procs,
81 recv_type, dst, tag, comm, &status);
83 last_recv_count = Status::get_count(&status, recv_type);
84 curr_size += last_recv_count;
88 if (dst_tree_root + mask > num_procs) {
90 num_procs_completed = num_procs - rank_tree_root - mask;
91 /* num_procs_completed is the number of processes in this
92 subtree that have all the data. Send data to others
93 in a tree fashion. First find root of current tree
94 that is being divided into two. k is the number of
95 least-significant bits in this process's rank that
96 must be zeroed out to find the rank of the root */
106 tmp_mask = mask >> 1;
109 dst = rank ^ tmp_mask;
111 tree_root = rank >> k;
114 /* send only if this proc has data and destination
115 doesn't have data. at any step, multiple processes
116 can send if they have the data */
119 && (rank < tree_root + num_procs_completed)
120 && (dst >= tree_root + num_procs_completed)) {
121 Request::send(tmp_buff + dst_tree_root * send_increment,
122 last_recv_count, send_type, dst, tag, comm);
126 /* recv only if this proc. doesn't have data and sender
129 else if ((dst < rank)
130 && (dst < tree_root + num_procs_completed)
131 && (rank >= tree_root + num_procs_completed)) {
132 Request::recv(tmp_buff + dst_tree_root * send_increment,
133 mask * num_procs * send_count, send_type, dst,
136 last_recv_count = Status::get_count(&status, send_type);
137 curr_size += last_recv_count;
149 for (i = 0; i < num_procs; i++)
150 Request::sendrecv(tmp_buff + (rank + i * num_procs) * send_count * extent,
151 send_count, send_type, rank, tag,
152 recv_ptr + (i * recv_count * extent),
153 recv_count, recv_type, rank, tag, comm, &status);
154 smpi_free_tmp_buffer(tmp_buff);