Actual source code: mpb_aij.c
petsc-3.4.0 2013-05-13
1: #include <../src/mat/impls/aij/mpi/mpiaij.h>
5: /*
6: Developers Note: This is used directly by some preconditioners, hence is PETSC_EXTERN
7: */
8: PETSC_EXTERN PetscErrorCode MatGetMultiProcBlock_MPIAIJ(Mat mat, MPI_Comm subComm, MatReuse scall,Mat *subMat)
9: {
11: Mat_MPIAIJ *aij = (Mat_MPIAIJ*)mat->data;
12: Mat_SeqAIJ *aijB = (Mat_SeqAIJ*)aij->B->data;
13: PetscMPIInt commRank,subCommSize,subCommRank;
14: PetscMPIInt *commRankMap,subRank,rank,commsize;
15: PetscInt *garrayCMap,col,i,j,*nnz,newRow,newCol;
18: MPI_Comm_size(PetscObjectComm((PetscObject)mat),&commsize);
19: MPI_Comm_size(subComm,&subCommSize);
21: /* create subMat object with the relavent layout */
22: if (scall == MAT_INITIAL_MATRIX) {
23: MatCreate(subComm,subMat);
24: MatSetType(*subMat,MATMPIAIJ);
25: MatSetSizes(*subMat,mat->rmap->n,mat->cmap->n,PETSC_DECIDE,PETSC_DECIDE);
26: MatSetBlockSizes(*subMat,mat->rmap->bs,mat->cmap->bs);
28: /* need to setup rmap and cmap before Preallocation */
29: PetscLayoutSetBlockSize((*subMat)->rmap,mat->rmap->bs);
30: PetscLayoutSetBlockSize((*subMat)->cmap,mat->cmap->bs);
31: PetscLayoutSetUp((*subMat)->rmap);
32: PetscLayoutSetUp((*subMat)->cmap);
33: }
35: /* create a map of comm_rank from subComm to comm - should commRankMap and garrayCMap be kept for reused? */
36: MPI_Comm_rank(PetscObjectComm((PetscObject)mat),&commRank);
37: MPI_Comm_rank(subComm,&subCommRank);
38: PetscMalloc(subCommSize*sizeof(PetscMPIInt),&commRankMap);
39: MPI_Allgather(&commRank,1,MPI_INT,commRankMap,1,MPI_INT,subComm);
41: /* Traverse garray and identify column indices [of offdiag mat] that
42: should be discarded. For the ones not discarded, store the newCol+1
43: value in garrayCMap */
44: PetscMalloc(aij->B->cmap->n*sizeof(PetscInt),&garrayCMap);
45: PetscMemzero(garrayCMap,aij->B->cmap->n*sizeof(PetscInt));
46: for (i=0; i<aij->B->cmap->n; i++) {
47: col = aij->garray[i];
48: for (subRank=0; subRank<subCommSize; subRank++) {
49: rank = commRankMap[subRank];
50: if ((col >= mat->cmap->range[rank]) && (col < mat->cmap->range[rank+1])) {
51: garrayCMap[i] = (*subMat)->cmap->range[subRank] + col - mat->cmap->range[rank]+1;
52: break;
53: }
54: }
55: }
57: if (scall == MAT_INITIAL_MATRIX) {
58: /* Now compute preallocation for the offdiag mat */
59: PetscMalloc(aij->B->rmap->n*sizeof(PetscInt),&nnz);
60: PetscMemzero(nnz,aij->B->rmap->n*sizeof(PetscInt));
61: for (i=0; i<aij->B->rmap->n; i++) {
62: for (j=aijB->i[i]; j<aijB->i[i+1]; j++) {
63: if (garrayCMap[aijB->j[j]]) nnz[i]++;
64: }
65: }
66: MatMPIAIJSetPreallocation(*(subMat),0,NULL,0,nnz);
68: /* reuse diag block with the new submat */
69: MatDestroy(&((Mat_MPIAIJ*)((*subMat)->data))->A);
71: ((Mat_MPIAIJ*)((*subMat)->data))->A = aij->A;
73: PetscObjectReference((PetscObject)aij->A);
74: } else if (((Mat_MPIAIJ*)(*subMat)->data)->A != aij->A) {
75: PetscObject obj = (PetscObject)((Mat_MPIAIJ*)((*subMat)->data))->A;
77: PetscObjectReference((PetscObject)obj);
79: ((Mat_MPIAIJ*)((*subMat)->data))->A = aij->A;
81: PetscObjectReference((PetscObject)aij->A);
82: }
84: /* Now traverse aij->B and insert values into subMat */
85: for (i=0; i<aij->B->rmap->n; i++) {
86: newRow = (*subMat)->rmap->range[subCommRank] + i;
87: for (j=aijB->i[i]; j<aijB->i[i+1]; j++) {
88: newCol = garrayCMap[aijB->j[j]];
89: if (newCol) {
90: newCol--; /* remove the increment */
91: MatSetValues(*subMat,1,&newRow,1,&newCol,(aijB->a+j),INSERT_VALUES);
92: }
93: }
94: }
96: /* assemble the submat */
97: MatAssemblyBegin(*subMat,MAT_FINAL_ASSEMBLY);
98: MatAssemblyEnd(*subMat,MAT_FINAL_ASSEMBLY);
100: /* deallocate temporary data */
101: PetscFree(commRankMap);
102: PetscFree(garrayCMap);
103: if (scall == MAT_INITIAL_MATRIX) {
104: PetscFree(nnz);
105: }
106: return(0);
107: }