1 /*
2 * ex193.c
3 *
4 * Created on: Jul 29, 2015
5 * Author: Fande Kong fdkong.jd@gmail.com
6 */
7 /*
8 * An example demonstrates how to use hierarchical partitioning approach
9 */
10
11 #include <petscmat.h>
12
13 static char help[] = "Illustrates use of hierarchical partitioning.\n";
14
main(int argc,char ** args)15 int main(int argc, char **args)
16 {
17 Mat A; /* matrix */
18 PetscInt m, n; /* mesh dimensions in x- and y- directions */
19 PetscInt i, j, Ii, J, Istart, Iend;
20 PetscMPIInt size;
21 PetscScalar v;
22 MatPartitioning part;
23 IS coarseparts, fineparts;
24 IS is, isn, isrows;
25 MPI_Comm comm;
26
27 PetscFunctionBeginUser;
28 PetscCall(PetscInitialize(&argc, &args, NULL, help));
29 comm = PETSC_COMM_WORLD;
30 PetscCallMPI(MPI_Comm_size(comm, &size));
31 PetscOptionsBegin(comm, NULL, "ex193", "hierarchical partitioning");
32 m = 15;
33 PetscCall(PetscOptionsInt("-M", "Number of mesh points in the x-direction", "partitioning", m, &m, NULL));
34 n = 15;
35 PetscCall(PetscOptionsInt("-N", "Number of mesh points in the y-direction", "partitioning", n, &n, NULL));
36 PetscOptionsEnd();
37
38 /*
39 Assemble the matrix for the five point stencil (finite difference), YET AGAIN
40 */
41 PetscCall(MatCreate(comm, &A));
42 PetscCall(MatSetSizes(A, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
43 PetscCall(MatSetFromOptions(A));
44 PetscCall(MatSetUp(A));
45 PetscCall(MatGetOwnershipRange(A, &Istart, &Iend));
46 for (Ii = Istart; Ii < Iend; Ii++) {
47 v = -1.0;
48 i = Ii / n;
49 j = Ii - i * n;
50 if (i > 0) {
51 J = Ii - n;
52 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
53 }
54 if (i < m - 1) {
55 J = Ii + n;
56 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
57 }
58 if (j > 0) {
59 J = Ii - 1;
60 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
61 }
62 if (j < n - 1) {
63 J = Ii + 1;
64 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
65 }
66 v = 4.0;
67 PetscCall(MatSetValues(A, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
68 }
69 PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
70 PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
71 PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
72 /*
73 Partition the graph of the matrix
74 */
75 PetscCall(MatPartitioningCreate(comm, &part));
76 PetscCall(MatPartitioningSetAdjacency(part, A));
77 PetscCall(MatPartitioningSetType(part, MATPARTITIONINGHIERARCH));
78 PetscCall(MatPartitioningHierarchicalSetNcoarseparts(part, 2));
79 PetscCall(MatPartitioningHierarchicalSetNfineparts(part, 4));
80 PetscCall(MatPartitioningSetFromOptions(part));
81 /* get new processor owner number of each vertex */
82 PetscCall(MatPartitioningApply(part, &is));
83 /* coarse parts */
84 PetscCall(MatPartitioningHierarchicalGetCoarseparts(part, &coarseparts));
85 PetscCall(ISView(coarseparts, PETSC_VIEWER_STDOUT_WORLD));
86 /* fine parts */
87 PetscCall(MatPartitioningHierarchicalGetFineparts(part, &fineparts));
88 PetscCall(ISView(fineparts, PETSC_VIEWER_STDOUT_WORLD));
89 /* partitioning */
90 PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
91 /* get new global number of each old global number */
92 PetscCall(ISPartitioningToNumbering(is, &isn));
93 PetscCall(ISView(isn, PETSC_VIEWER_STDOUT_WORLD));
94 PetscCall(ISBuildTwoSided(is, NULL, &isrows));
95 PetscCall(ISView(isrows, PETSC_VIEWER_STDOUT_WORLD));
96 PetscCall(ISDestroy(&is));
97 PetscCall(ISDestroy(&coarseparts));
98 PetscCall(ISDestroy(&fineparts));
99 PetscCall(ISDestroy(&isrows));
100 PetscCall(ISDestroy(&isn));
101 PetscCall(MatPartitioningDestroy(&part));
102 PetscCall(MatDestroy(&A));
103 PetscCall(PetscFinalize());
104 return 0;
105 }
106
107 /*TEST
108
109 test:
110 nsize: 4
111 args: -mat_partitioning_hierarchical_Nfineparts 2
112 requires: parmetis
113 TODO: cannot run because parmetis does reproduce across all machines, probably due to nonportable random number generator
114
115 TEST*/
116