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,
30 *results, *counter_vals;
31 MPI_Datatype get_type;
35 MTest_Init(&argc,&argv);
36 MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
37 MPI_Comm_rank(MPI_COMM_WORLD,&rank);
40 /* allocate counter memory and initialize to 0 */
41 counter_mem = (int *) calloc(nprocs, sizeof(int));
42 MPI_Win_create(counter_mem, nprocs*sizeof(int), sizeof(int),
43 MPI_INFO_NULL, MPI_COMM_WORLD, &win);
48 /* gather the results from other processes, sort them, and check
49 whether they represent a counter being incremented by 1 */
51 results = (int *) malloc(NTIMES*nprocs*sizeof(int));
52 for (i=0; i<NTIMES*nprocs; i++)
55 MPI_Gather(MPI_IN_PLACE, 0, MPI_DATATYPE_NULL, results, NTIMES, MPI_INT,
58 qsort(results+NTIMES, NTIMES*(nprocs-1), sizeof(int), compar);
60 for (i=NTIMES+1; i<(NTIMES*nprocs); i++)
61 if (results[i] != results[i-1] + 1)
69 blens[1] = nprocs - rank - 1;
72 MPI_Type_indexed(2, blens, disps, MPI_INT, &get_type);
73 MPI_Type_commit(&get_type);
75 val_array = (int *) malloc(nprocs * sizeof(int));
77 /* allocate array to store the values obtained from the
78 fetch-and-add counter */
79 counter_vals = (int *) malloc(NTIMES * sizeof(int));
81 MPI_Win_create(NULL, 0, 1, MPI_INFO_NULL, MPI_COMM_WORLD, &win);
83 for (i=0; i<NTIMES; i++) {
84 Get_nextval(win, val_array, get_type, rank, nprocs, counter_vals+i);
85 /* printf("Rank %d, counter %d\n", rank, value); */
91 MPI_Type_free(&get_type);
93 /* gather the results to the root */
94 MPI_Gather(counter_vals, NTIMES, MPI_INT, NULL, 0, MPI_DATATYPE_NULL,
105 void Get_nextval(MPI_Win win, int *val_array, MPI_Datatype get_type,
106 int rank, int nprocs, int *value)
110 MPI_Win_lock(MPI_LOCK_EXCLUSIVE, 0, 0, win);
111 MPI_Accumulate(&one, 1, MPI_INT, 0, rank, 1, MPI_INT, MPI_SUM, win);
112 MPI_Get(val_array, 1, get_type, 0, 0, 1, get_type, win);
113 MPI_Win_unlock(0, win);
116 val_array[rank] = localvalue;
117 for (i=0; i<nprocs; i++)
118 *value = *value + val_array[i];
123 int compar(const void *a, const void *b)
125 return (*((int *)a) - *((int *)b));