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