main.c 6.52 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
#include <limits.h>
#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include "configuration.h"
#include "mpicomm.h"
#include "mesh.h"
#include "field.h"

#ifdef DEBUG_ATTACH
#include <unistd.h>
void wait_for_debugger();
#endif

void print_decomposition(const conf_t *configuraiton, const box_t *decomposition, FILE *f);
void print_adjacency_matrix(const mesh_t *mesh, const conf_t *configuraiton, FILE *f);

void halo_exchange_demo(const mesh_t *mesh, const conf_t *configuration);

int main(int argc, char *argv[])
{
   int mpi_rank, nprocs;
   const char* error;
   mesh_t mesh;

   MPI_Init(&argc, &argv);

   MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
   MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

   // initialize random number generator
   srand((mpi_rank + 17) * (int)time(NULL));

   conf_t configuration;
   conf_init(&configuration);

   if(mpi_rank == 0) {
      // parse comand line args on root process only
      error = conf_set_from_args(&configuration, argc, argv);
      if(error) {
         fprintf(stderr, "%s\n", error);
         MPI_Abort(MPI_COMM_WORLD, EXIT_FAILURE);
      }
   }

   // Broadcast configuration (nonblocking)
   MPI_Request req_bcast_conf;
   mpi_broadcast_configuration_start(&configuration, &req_bcast_conf);

   // Create and broadcast decomposition
   box_t *decomposition = malloc(nprocs * sizeof(*decomposition));
   if(mpi_rank == 0) {
      const box_t *cube = &configuration.global_domain;
      box_decompose(cube, nprocs, decomposition);
   }
   mpi_broadcast_decomposition(decomposition);

   // Finish nonblocking configuration broadcast
   mpi_broadcast_configuration_finish(&req_bcast_conf);

   if(info_enabled(&configuration)) {
      conf_print(&configuration, stdout);
      print_decomposition(&configuration, decomposition, stdout);
   }

#ifdef DEBUG_ATTACH
   if(mpi_rank == configuration.debug_rank) {
      wait_for_debugger();
   }
#endif

   mesh_init(&mesh, &configuration, decomposition);
   print_adjacency_matrix(&mesh, &configuration, stdout);

   halo_exchange_demo(&mesh, &configuration);

   mesh_free(&mesh);

   free(decomposition);
   MPI_Finalize();

   return EXIT_SUCCESS;
}

// --------------------------------------------------------------------------

void halo_exchange_demo(const mesh_t *mesh, const conf_t *configuration)
{
   int mpi_rank, i, n;
   int_field_t field;
   const neighbor_info *nb;

   int_field_init(&field, configuration, mesh);

   MPI_Comm_rank(mesh->communicator, &mpi_rank);

   // Set field data and exchange halo information
   n = configuration->n_iterations;
   if(info_enabled(configuration)) {
      printf("Exchanging halo information (%d iterations)...\n\n", n);
   }

   for(i = 0; i < n; i++) {
      if(trace_enabled(configuration)) {
         printf("Iteration %d\n", i);
      }
      int_field_set_constant(&field, mpi_rank);
      int_field_halo_exchange(&field);
   }

   if(info_enabled(configuration)) {
      printf("Validating...\n\n");
   }

   // Validate local field data
   if(!int_field_check_value(&field, &mesh->local_domain, mpi_rank)) {
      fprintf(stderr, "ERROR (rank %d): Local cell data corrupted.\n", mpi_rank);
      MPI_Abort(MPI_COMM_WORLD, EXIT_FAILURE);
   }

   // Validate halo data received from each neighbor
   for(i = 0; i < mesh->n_neighbors; i++) {
      nb = &mesh->neighbors[i];
      if(!int_field_check_value(&field, &nb->halo_incoming.domain, nb->mpi_rank)) {
         fprintf(stderr, "ERROR (rank %d): Halo values for neighbor rank %d not correct.\n",
                 mpi_rank, nb->mpi_rank);
         MPI_Abort(MPI_COMM_WORLD, EXIT_FAILURE);
      }
   }

   if(info_enabled(configuration)) {
      printf("Validation successful.\n\n");
   }

   int_field_free(&field);
}

void print_decomposition(const conf_t *configuration, const box_t *boxes, FILE *f)
{
   int nprocs;
   MPI_Comm_size(MPI_COMM_WORLD, &nprocs);

   long volume, min_volume = LONG_MAX, max_volume = 0;
   int i, j;
   for(i = 0; i < nprocs; i++) {
      volume = boxes[i].volume;
      if(min_volume > volume) min_volume = boxes[i].volume;
      if(max_volume < volume) max_volume = boxes[i].volume;
   }
   fprintf(f, "Cells per processor (min-max): %ld - %ld\n\n", min_volume, max_volume);

   if(trace_enabled(configuration)) {
      char buf[128];
      box_t intersection;
      fprintf(f, "Decomposition:\n");
      for(i = 0; i < nprocs; i++) {
         fprintf(f, " * box %5d: %s\n", i, box_to_string(&boxes[i], buf, sizeof(buf))); 

         for(j = 0; j < i; j++) {
            box_intersect(&boxes[i], &boxes[j], &intersection);
            if(!box_is_empty(&intersection)){
               fprintf(f, "   * intersects with box %d\n", j);
            }
         }
      }
      fprintf(f, "\n");
   }
}

void print_adjacency_matrix(const mesh_t *mesh, const conf_t *configuration, FILE *f)
{
   if(configuration->verbosity_level >= DEBUG)
   {
      int mpi_rank, nprocs;
      int *sendbuf, *recvbuf, *row;
      neighbor_info *nb;
      int i, j, min, max, n;

      MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
      MPI_Comm_rank(MPI_COMM_WORLD, &mpi_rank);

      sendbuf = calloc(nprocs, sizeof(*sendbuf));
      recvbuf = mpi_rank == 0 ? calloc(nprocs * nprocs, sizeof(*recvbuf)) : NULL;

      for(i = 0; i < mesh->n_neighbors; i++) {
         nb = &mesh->neighbors[i];
         sendbuf[nb->mpi_rank] = nb->halo_incoming.domain.volume;
      }

      MPI_Gather(
            sendbuf, nprocs, MPI_INT,
            recvbuf, nprocs, MPI_INT,
            0, MPI_COMM_WORLD);

      if(mpi_rank == 0) {
         fprintf(f, "Adjacency matrix:\n");
         fprintf(f, "%2s ", "");
         for(i = 0; i < nprocs; i++) {
            fprintf(f, "%2d ", i);
         }
         fprintf(f, "\n");

         for(j = 0; j < nprocs; j++) {
            row = recvbuf + j * nprocs;

            fprintf(f, "%2d ", j);
            for(i = 0; i < nprocs; i++) {
               fprintf(f, "%2s ", row[i] ? "X" : "");
            }
            fprintf(f, "\n");
         }
         fprintf(f, "\n");

         min = INT_MAX; max = 0;
         for(i = 0; i < nprocs * nprocs; i++) {
            n = recvbuf[i];
            if(n > 0 && min > n) min = recvbuf[i];
            if(max < n) max = n;
         }
222
         fprintf(f, "Number of halo cells per neighbor (min-max): %d - %d\n\n", min, max);
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
         free(recvbuf);
      }
      free(sendbuf);
   }
}

#ifdef DEBUG_ATTACH
void wait_for_debugger()
{
   int rank;
   volatile int resume = 0;
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);

   printf("Rank %d (pid %d) waiting for debugger to attach...\n", rank, getpid());
   while(!resume) {
      sleep(1);
   }
}
#endif