Actual source code: ex83.c
2: static char help[] = "Partition tiny grid using hierarchical partitioning and increase overlap using MatIncreaseOverlapSplit.\n\n";
4: /*T
5: Concepts: partitioning
6: Processors: 4
7: T*/
9: /*
10: Include "petscmat.h" so that we can use matrices. Note that this file
11: automatically includes:
12: petscsys.h - base PETSc routines petscvec.h - vectors
13: petscmat.h - matrices
14: petscis.h - index sets
15: petscviewer.h - viewers
16: */
17: #include <petscmat.h>
19: int main(int argc,char **args)
20: {
21: Mat A,B;
22: PetscMPIInt rank,size,membershipKey;
23: PetscInt *ia,*ja,*indices_sc,isrows_localsize;
24: const PetscInt *indices;
25: MatPartitioning part;
26: IS is,isrows,isrows_sc;
27: IS coarseparts,fineparts;
28: MPI_Comm comm,scomm;
30: PetscInitialize(&argc,&args,(char*)0,help);
31: comm = PETSC_COMM_WORLD;
32: MPI_Comm_size(comm,&size);
34: MPI_Comm_rank(comm,&rank);
35: /*set a small matrix */
36: PetscMalloc1(5,&ia);
37: PetscMalloc1(16,&ja);
38: if (rank == 0) {
39: ja[0] = 1; ja[1] = 4; ja[2] = 0; ja[3] = 2; ja[4] = 5; ja[5] = 1; ja[6] = 3; ja[7] = 6;
40: ja[8] = 2; ja[9] = 7;
41: ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
42: membershipKey = 0;
43: } else if (rank == 1) {
44: ja[0] = 0; ja[1] = 5; ja[2] = 8; ja[3] = 1; ja[4] = 4; ja[5] = 6; ja[6] = 9; ja[7] = 2;
45: ja[8] = 5; ja[9] = 7; ja[10] = 10; ja[11] = 3; ja[12] = 6; ja[13] = 11;
46: ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
47: membershipKey = 0;
48: } else if (rank == 2) {
49: ja[0] = 4; ja[1] = 9; ja[2] = 12; ja[3] = 5; ja[4] = 8; ja[5] = 10; ja[6] = 13; ja[7] = 6;
50: ja[8] = 9; ja[9] = 11; ja[10] = 14; ja[11] = 7; ja[12] = 10; ja[13] = 15;
51: ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
52: membershipKey = 1;
53: } else {
54: ja[0] = 8; ja[1] = 13; ja[2] = 9; ja[3] = 12; ja[4] = 14; ja[5] = 10; ja[6] = 13; ja[7] = 15;
55: ja[8] = 11; ja[9] = 14;
56: ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
57: membershipKey = 1;
58: }
59: MatCreateMPIAdj(comm,4,16,ia,ja,NULL,&A);
60: MatView(A,PETSC_VIEWER_STDOUT_WORLD);
61: /*
62: Partition the graph of the matrix
63: */
64: MatPartitioningCreate(comm,&part);
65: MatPartitioningSetAdjacency(part,A);
66: MatPartitioningSetType(part,MATPARTITIONINGHIERARCH);
67: MatPartitioningHierarchicalSetNcoarseparts(part,2);
68: MatPartitioningHierarchicalSetNfineparts(part,2);
69: MatPartitioningSetFromOptions(part);
70: /* get new processor owner number of each vertex */
71: MatPartitioningApply(part,&is);
72: /* coarse parts */
73: MatPartitioningHierarchicalGetCoarseparts(part,&coarseparts);
74: ISView(coarseparts,PETSC_VIEWER_STDOUT_WORLD);
75: /* fine parts */
76: MatPartitioningHierarchicalGetFineparts(part,&fineparts);
77: ISView(fineparts,PETSC_VIEWER_STDOUT_WORLD);
78: /* partitioning */
79: ISView(is,PETSC_VIEWER_STDOUT_WORLD);
80: /* compute coming rows */
81: ISBuildTwoSided(is,NULL,&isrows);
82: ISView(isrows,PETSC_VIEWER_STDOUT_WORLD);
83: /*create a sub-communicator */
84: MPI_Comm_split(comm, membershipKey,rank,&scomm);
85: ISGetLocalSize(isrows,&isrows_localsize);
86: PetscMalloc1(isrows_localsize,&indices_sc);
87: ISGetIndices(isrows,&indices);
88: PetscArraycpy(indices_sc,indices,isrows_localsize);
89: ISRestoreIndices(isrows,&indices);
90: ISDestroy(&is);
91: ISDestroy(&coarseparts);
92: ISDestroy(&fineparts);
93: ISDestroy(&isrows);
94: MatPartitioningDestroy(&part);
95: /*create a sub-IS on the sub communicator */
96: ISCreateGeneral(scomm,isrows_localsize,indices_sc,PETSC_OWN_POINTER,&isrows_sc);
97: MatConvert(A,MATMPIAIJ,MAT_INITIAL_MATRIX,&B);
98: #if 1
99: MatView(B,PETSC_VIEWER_STDOUT_WORLD);
100: #endif
101: /*increase overlap */
102: MatIncreaseOverlapSplit(B,1,&isrows_sc,1);
103: ISView(isrows_sc,NULL);
104: ISDestroy(&isrows_sc);
105: /*
106: Free work space. All PETSc objects should be destroyed when they
107: are no longer needed.
108: */
109: MatDestroy(&A);
110: MatDestroy(&B);
111: PetscFinalize();
112: return 0;
113: }