1 /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
3 * (C) 2001 by Argonne National Laboratory.
4 * See COPYRIGHT in top-level directory.
11 /* Fetch and add example from Using MPI-2 (the non-scalable version,
15 #define NTIMES 20 /* no of times each process calls the counter
18 int localvalue = 0; /* contribution of this process to the counter. We
19 * define it as a global variable because attribute
20 * caching on the window is not enabled yet. */
22 void Get_nextval(MPI_Win win, int *val_array, MPI_Datatype get_type,
23 int rank, int nprocs, int *value);
25 int compar(const void *a, const void *b);
27 int main(int argc, char *argv[])
29 int rank, nprocs, i, blens[2], disps[2], *counter_mem, *val_array, *results, *counter_vals;
30 MPI_Datatype get_type;
34 MTest_Init(&argc, &argv);
35 MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
36 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
39 /* allocate counter memory and initialize to 0 */
40 counter_mem = (int *) calloc(nprocs, sizeof(int));
41 MPI_Win_create(counter_mem, nprocs * sizeof(int), sizeof(int),
42 MPI_INFO_NULL, MPI_COMM_WORLD, &win);
47 /* gather the results from other processes, sort them, and check
48 * whether they represent a counter being incremented by 1 */
50 results = (int *) malloc(NTIMES * nprocs * sizeof(int));
51 for (i = 0; i < NTIMES * nprocs; i++)
54 MPI_Gather(MPI_IN_PLACE, 0, MPI_DATATYPE_NULL, results, NTIMES, MPI_INT, 0, MPI_COMM_WORLD);
56 qsort(results + NTIMES, NTIMES * (nprocs - 1), sizeof(int), compar);
58 for (i = NTIMES + 1; i < (NTIMES * nprocs); i++)
59 if (results[i] != results[i - 1] + 1)
67 blens[1] = nprocs - rank - 1;
70 MPI_Type_indexed(2, blens, disps, MPI_INT, &get_type);
71 MPI_Type_commit(&get_type);
73 val_array = (int *) malloc(nprocs * sizeof(int));
75 /* allocate array to store the values obtained from the
76 * fetch-and-add counter */
77 counter_vals = (int *) malloc(NTIMES * sizeof(int));
79 MPI_Win_create(NULL, 0, 1, MPI_INFO_NULL, MPI_COMM_WORLD, &win);
81 for (i = 0; i < NTIMES; i++) {
82 Get_nextval(win, val_array, get_type, rank, nprocs, counter_vals + i);
83 /* printf("Rank %d, counter %d\n", rank, localvalue); */
89 MPI_Type_free(&get_type);
91 /* gather the results to the root */
92 MPI_Gather(counter_vals, NTIMES, MPI_INT, NULL, 0, MPI_DATATYPE_NULL, 0, MPI_COMM_WORLD);
102 void Get_nextval(MPI_Win win, int *val_array, MPI_Datatype get_type,
103 int rank, int nprocs, int *value)
107 MPI_Win_lock(MPI_LOCK_EXCLUSIVE, 0, 0, win);
108 MPI_Accumulate(&one, 1, MPI_INT, 0, rank, 1, MPI_INT, MPI_SUM, win);
109 MPI_Get(val_array, 1, get_type, 0, 0, 1, get_type, win);
110 MPI_Win_unlock(0, win);
113 val_array[rank] = localvalue;
114 for (i = 0; i < nprocs; i++)
115 *value = *value + val_array[i];
120 int compar(const void *a, const void *b)
122 return (*((int *) a) - *((int *) b));