1 #include <../src/mat/impls/aij/mpi/mpiaij.h> 2 3 #undef __FUNCT__ 4 #define __FUNCT__ "MatGetMultiProcBlock_MPIAIJ" 5 PetscErrorCode MatGetMultiProcBlock_MPIAIJ(Mat mat, MPI_Comm subComm, Mat* subMat) 6 { 7 PetscErrorCode ierr; 8 Mat_MPIAIJ *aij = (Mat_MPIAIJ*)mat->data; 9 Mat_SeqAIJ* aijB = (Mat_SeqAIJ*)aij->B->data; 10 PetscMPIInt commRank,subCommSize,subCommRank; 11 PetscMPIInt *commRankMap,subRank,rank,commsize; 12 PetscInt *garrayCMap,col,i,j,*nnz,newRow,newCol; 13 14 PetscFunctionBegin; 15 ierr = MPI_Comm_size(((PetscObject)mat)->comm,&commsize);CHKERRQ(ierr); 16 ierr = MPI_Comm_size(subComm,&subCommSize);CHKERRQ(ierr); 17 18 /* create subMat object with the relavent layout */ 19 ierr = MatCreate(subComm,subMat);CHKERRQ(ierr); 20 ierr = MatSetType(*subMat,MATMPIAIJ);CHKERRQ(ierr); 21 ierr = MatSetSizes(*subMat,mat->rmap->n,mat->cmap->n,PETSC_DECIDE,PETSC_DECIDE);CHKERRQ(ierr); 22 /* need to setup rmap and cmap before Preallocation */ 23 ierr = PetscLayoutSetBlockSize((*subMat)->rmap,mat->rmap->bs);CHKERRQ(ierr); 24 ierr = PetscLayoutSetBlockSize((*subMat)->cmap,mat->cmap->bs);CHKERRQ(ierr); 25 ierr = PetscLayoutSetUp((*subMat)->rmap);CHKERRQ(ierr); 26 ierr = PetscLayoutSetUp((*subMat)->cmap);CHKERRQ(ierr); 27 28 /* create a map of comm_rank from subComm to comm */ 29 ierr = MPI_Comm_rank(((PetscObject)mat)->comm,&commRank);CHKERRQ(ierr); 30 ierr = MPI_Comm_rank(subComm,&subCommRank);CHKERRQ(ierr); 31 ierr = PetscMalloc(subCommSize*sizeof(PetscMPIInt),&commRankMap);CHKERRQ(ierr); 32 ierr = MPI_Allgather(&commRank,1,MPI_INT,commRankMap,1,MPI_INT,subComm);CHKERRQ(ierr); 33 34 /* Traverse garray and identify column indices [of offdiag mat] that 35 should be discarded. For the ones not discarded, store the newCol+1 36 value in garrayCMap */ 37 ierr = PetscMalloc(aij->B->cmap->n*sizeof(PetscInt),&garrayCMap);CHKERRQ(ierr); 38 ierr = PetscMemzero(garrayCMap,aij->B->cmap->n*sizeof(PetscInt));CHKERRQ(ierr); 39 for (i=0; i<aij->B->cmap->n; i++) { 40 col = aij->garray[i]; 41 for (subRank=0; subRank<subCommSize; subRank++) { 42 rank = commRankMap[subRank]; 43 if ((col >= mat->cmap->range[rank]) && (col < mat->cmap->range[rank+1])) { 44 garrayCMap[i] = (*subMat)->cmap->range[subRank] + col - mat->cmap->range[rank]+1; 45 break; 46 } 47 } 48 } 49 50 /* Now compute preallocation for the offdiag mat */ 51 ierr = PetscMalloc(aij->B->rmap->n*sizeof(PetscInt),&nnz);CHKERRQ(ierr); 52 ierr = PetscMemzero(nnz,aij->B->rmap->n*sizeof(PetscInt));CHKERRQ(ierr); 53 for (i=0; i<aij->B->rmap->n; i++) { 54 for (j=aijB->i[i]; j<aijB->i[i+1]; j++) { 55 if (garrayCMap[aijB->j[j]]) nnz[i]++; 56 } 57 } 58 ierr = MatMPIAIJSetPreallocation(*(subMat),PETSC_NULL,PETSC_NULL,PETSC_NULL,nnz);CHKERRQ(ierr); 59 60 /* reuse diag block with the new submat */ 61 ierr = MatDestroy(&((Mat_MPIAIJ*)((*subMat)->data))->A);CHKERRQ(ierr); 62 ((Mat_MPIAIJ*)((*subMat)->data))->A = aij->A; 63 ierr = PetscObjectReference((PetscObject)aij->A);CHKERRQ(ierr); 64 65 /* Now traverse aij->B and insert values into subMat */ 66 for (i=0; i<aij->B->rmap->n; i++) { 67 newRow = (*subMat)->rmap->range[subCommRank] + i; 68 for (j=aijB->i[i]; j<aijB->i[i+1]; j++) { 69 newCol = garrayCMap[aijB->j[j]]; 70 if (newCol) { 71 newCol--; /* remove the increment */ 72 ierr = MatSetValues(*subMat,1,&newRow,1,&newCol,(aijB->a+j),INSERT_VALUES);CHKERRQ(ierr); 73 } 74 } 75 } 76 77 /* assemble the submat */ 78 ierr = MatAssemblyBegin(*subMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 79 ierr = MatAssemblyEnd(*subMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr); 80 81 /* deallocate temporary data */ 82 ierr = PetscFree(commRankMap);CHKERRQ(ierr); 83 ierr = PetscFree(garrayCMap);CHKERRQ(ierr); 84 ierr = PetscFree(nnz);CHKERRQ(ierr); 85 PetscFunctionReturn(0); 86 } 87