1 static char help[] = "Example of using graph partitioning with a matrix in which some procs have empty ownership\n\n"; 2 3 #include <petscmat.h> 4 5 int main(int argc, char **args) 6 { 7 Mat A; 8 MatPartitioning part; 9 IS is; 10 PetscInt i, m, N, rstart, rend, nemptyranks, *emptyranks, nbigranks, *bigranks; 11 PetscMPIInt rank, size; 12 13 PetscFunctionBeginUser; 14 PetscCall(PetscInitialize(&argc, &args, (char *)0, help)); 15 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank)); 16 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size)); 17 18 nemptyranks = 10; 19 nbigranks = 10; 20 PetscCall(PetscMalloc2(nemptyranks, &emptyranks, nbigranks, &bigranks)); 21 22 PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "Partitioning example options", NULL); 23 PetscCall(PetscOptionsIntArray("-emptyranks", "Ranks to be skipped by partition", "", emptyranks, &nemptyranks, NULL)); 24 PetscCall(PetscOptionsIntArray("-bigranks", "Ranks to be overloaded", "", bigranks, &nbigranks, NULL)); 25 PetscOptionsEnd(); 26 27 m = 1; 28 for (i = 0; i < nemptyranks; i++) 29 if (rank == emptyranks[i]) m = 0; 30 for (i = 0; i < nbigranks; i++) 31 if (rank == bigranks[i]) m = 5; 32 33 PetscCall(MatCreate(PETSC_COMM_WORLD, &A)); 34 PetscCall(MatSetSizes(A, m, m, PETSC_DECIDE, PETSC_DECIDE)); 35 PetscCall(MatSetFromOptions(A)); 36 PetscCall(MatSeqAIJSetPreallocation(A, 3, NULL)); 37 PetscCall(MatMPIAIJSetPreallocation(A, 3, NULL, 2, NULL)); 38 PetscCall(MatSeqBAIJSetPreallocation(A, 1, 3, NULL)); 39 PetscCall(MatMPIBAIJSetPreallocation(A, 1, 3, NULL, 2, NULL)); 40 PetscCall(MatSeqSBAIJSetPreallocation(A, 1, 2, NULL)); 41 PetscCall(MatMPISBAIJSetPreallocation(A, 1, 2, NULL, 1, NULL)); 42 43 PetscCall(MatGetSize(A, NULL, &N)); 44 PetscCall(MatGetOwnershipRange(A, &rstart, &rend)); 45 for (i = rstart; i < rend; i++) { 46 const PetscInt cols[] = {(i + N - 1) % N, i, (i + 1) % N}; 47 const PetscScalar vals[] = {1, 1, 1}; 48 PetscCall(MatSetValues(A, 1, &i, 3, cols, vals, INSERT_VALUES)); 49 } 50 PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY)); 51 PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY)); 52 PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD)); 53 54 PetscCall(MatPartitioningCreate(PETSC_COMM_WORLD, &part)); 55 PetscCall(MatPartitioningSetAdjacency(part, A)); 56 PetscCall(MatPartitioningSetFromOptions(part)); 57 PetscCall(MatPartitioningApply(part, &is)); 58 PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD)); 59 PetscCall(ISDestroy(&is)); 60 PetscCall(MatPartitioningDestroy(&part)); 61 PetscCall(MatDestroy(&A)); 62 PetscCall(PetscFree2(emptyranks, bigranks)); 63 PetscCall(PetscFinalize()); 64 return 0; 65 } 66 67 /*TEST 68 69 test: 70 nsize: 8 71 args: -emptyranks 0,2,4 -bigranks 1,3,7 -mat_partitioning_type average 72 # cannot test with external package partitioners since they produce different results on different systems 73 74 TEST*/ 75