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 PetscErrorCode ierr; 13 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 ierr = PetscOptionsBegin(PETSC_COMM_WORLD,NULL,"Partitioning example options",NULL);PetscCall(ierr); 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 ierr = PetscOptionsEnd();PetscCall(ierr); 26 27 m = 1; 28 for (i=0; i<nemptyranks; i++) if (rank == emptyranks[i]) m = 0; 29 for (i=0; i<nbigranks; i++) if (rank == bigranks[i]) m = 5; 30 31 PetscCall(MatCreate(PETSC_COMM_WORLD,&A)); 32 PetscCall(MatSetSizes(A,m,m,PETSC_DECIDE,PETSC_DECIDE)); 33 PetscCall(MatSetFromOptions(A)); 34 PetscCall(MatSeqAIJSetPreallocation(A,3,NULL)); 35 PetscCall(MatMPIAIJSetPreallocation(A,3,NULL,2,NULL)); 36 PetscCall(MatSeqBAIJSetPreallocation(A,1,3,NULL)); 37 PetscCall(MatMPIBAIJSetPreallocation(A,1,3,NULL,2,NULL)); 38 PetscCall(MatSeqSBAIJSetPreallocation(A,1,2,NULL)); 39 PetscCall(MatMPISBAIJSetPreallocation(A,1,2,NULL,1,NULL)); 40 41 PetscCall(MatGetSize(A,NULL,&N)); 42 PetscCall(MatGetOwnershipRange(A,&rstart,&rend)); 43 for (i=rstart; i<rend; i++) { 44 const PetscInt cols[] = {(i+N-1)%N,i,(i+1)%N}; 45 const PetscScalar vals[] = {1,1,1}; 46 PetscCall(MatSetValues(A,1,&i,3,cols,vals,INSERT_VALUES)); 47 } 48 PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY)); 49 PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY)); 50 PetscCall(MatView(A,PETSC_VIEWER_STDOUT_WORLD)); 51 52 PetscCall(MatPartitioningCreate(PETSC_COMM_WORLD,&part)); 53 PetscCall(MatPartitioningSetAdjacency(part,A)); 54 PetscCall(MatPartitioningSetFromOptions(part)); 55 PetscCall(MatPartitioningApply(part,&is)); 56 PetscCall(ISView(is,PETSC_VIEWER_STDOUT_WORLD)); 57 PetscCall(ISDestroy(&is)); 58 PetscCall(MatPartitioningDestroy(&part)); 59 PetscCall(MatDestroy(&A)); 60 PetscCall(PetscFree2(emptyranks,bigranks)); 61 PetscCall(PetscFinalize()); 62 return 0; 63 } 64 65 /*TEST 66 67 test: 68 nsize: 8 69 args: -emptyranks 0,2,4 -bigranks 1,3,7 -mat_partitioning_type average 70 # cannot test with external package partitioners since they produce different results on different systems 71 72 TEST*/ 73