Actual source code: mpb_baij.c
1: #include <../src/mat/impls/baij/mpi/mpibaij.h>
3: PetscErrorCode MatGetMultiProcBlock_MPIBAIJ(Mat mat, MPI_Comm subComm, MatReuse scall, Mat *subMat)
4: {
5: Mat_MPIBAIJ *aij = (Mat_MPIBAIJ *)mat->data;
6: Mat_SeqBAIJ *aijB = (Mat_SeqBAIJ *)aij->B->data;
7: PetscMPIInt commRank, subCommSize, subCommRank;
8: PetscMPIInt *commRankMap, subRank, rank, commsize;
9: PetscInt *garrayCMap, col, i, j, *nnz, newRow, newCol, *newbRow, *newbCol, k, k1;
10: PetscInt bs = mat->rmap->bs;
11: PetscScalar *vals, *aijBvals;
13: MPI_Comm_size(PetscObjectComm((PetscObject)mat), &commsize);
14: MPI_Comm_size(subComm, &subCommSize);
16: /* create subMat object with the relevant layout */
17: if (scall == MAT_INITIAL_MATRIX) {
18: MatCreate(subComm, subMat);
19: MatSetType(*subMat, MATMPIBAIJ);
20: MatSetSizes(*subMat, mat->rmap->n, mat->cmap->n, PETSC_DECIDE, PETSC_DECIDE);
21: MatSetBlockSizes(*subMat, mat->rmap->bs, mat->cmap->bs);
23: /* need to setup rmap and cmap before Preallocation */
24: PetscLayoutSetBlockSize((*subMat)->rmap, mat->rmap->bs);
25: PetscLayoutSetBlockSize((*subMat)->cmap, mat->cmap->bs);
26: PetscLayoutSetUp((*subMat)->rmap);
27: PetscLayoutSetUp((*subMat)->cmap);
28: }
30: /* create a map of comm_rank from subComm to comm - should commRankMap and garrayCMap be kept for reused? */
31: MPI_Comm_rank(PetscObjectComm((PetscObject)mat), &commRank);
32: MPI_Comm_rank(subComm, &subCommRank);
33: PetscMalloc1(subCommSize, &commRankMap);
34: MPI_Allgather(&commRank, 1, MPI_INT, commRankMap, 1, MPI_INT, subComm);
36: /* Traverse garray and identify blocked column indices [of offdiag mat] that
37: should be discarded. For the ones not discarded, store the newCol+1
38: value in garrayCMap */
39: PetscCalloc1(aij->B->cmap->n / bs, &garrayCMap);
40: for (i = 0; i < aij->B->cmap->n / bs; i++) {
41: col = aij->garray[i]; /* blocked column index */
42: for (subRank = 0; subRank < subCommSize; subRank++) {
43: rank = commRankMap[subRank];
44: if ((col >= mat->cmap->range[rank] / bs) && (col < mat->cmap->range[rank + 1] / bs)) {
45: garrayCMap[i] = (((*subMat)->cmap->range[subRank] - mat->cmap->range[rank]) / bs + col + 1);
46: break;
47: }
48: }
49: }
51: if (scall == MAT_INITIAL_MATRIX) {
52: /* Now compute preallocation for the offdiag mat */
53: PetscCalloc1(aij->B->rmap->n / bs, &nnz);
54: for (i = 0; i < aij->B->rmap->n / bs; i++) {
55: for (j = aijB->i[i]; j < aijB->i[i + 1]; j++) {
56: if (garrayCMap[aijB->j[j]]) nnz[i]++;
57: }
58: }
59: MatMPIBAIJSetPreallocation(*(subMat), bs, 0, NULL, 0, nnz);
61: /* reuse diag block with the new submat */
62: MatDestroy(&((Mat_MPIBAIJ *)((*subMat)->data))->A);
64: ((Mat_MPIBAIJ *)((*subMat)->data))->A = aij->A;
66: PetscObjectReference((PetscObject)aij->A);
67: } else if (((Mat_MPIBAIJ *)(*subMat)->data)->A != aij->A) {
68: PetscObject obj = (PetscObject)((Mat_MPIBAIJ *)((*subMat)->data))->A;
70: PetscObjectReference((PetscObject)obj);
72: ((Mat_MPIBAIJ *)((*subMat)->data))->A = aij->A;
74: PetscObjectReference((PetscObject)aij->A);
75: }
77: /* Now traverse aij->B and insert values into subMat */
78: PetscMalloc3(bs, &newbRow, bs, &newbCol, bs * bs, &vals);
79: for (i = 0; i < aij->B->rmap->n / bs; i++) {
80: newRow = (*subMat)->rmap->range[subCommRank] + i * bs;
81: for (j = aijB->i[i]; j < aijB->i[i + 1]; j++) {
82: newCol = garrayCMap[aijB->j[j]];
83: if (newCol) {
84: newCol--; /* remove the increment */
85: newCol *= bs;
86: for (k = 0; k < bs; k++) {
87: newbRow[k] = newRow + k;
88: newbCol[k] = newCol + k;
89: }
90: /* copy column-oriented aijB->a into row-oriented vals */
91: aijBvals = aijB->a + j * bs * bs;
92: for (k1 = 0; k1 < bs; k1++) {
93: for (k = 0; k < bs; k++) vals[k1 + k * bs] = *aijBvals++;
94: }
95: MatSetValues(*subMat, bs, newbRow, bs, newbCol, vals, INSERT_VALUES);
96: }
97: }
98: }
99: MatAssemblyBegin(*subMat, MAT_FINAL_ASSEMBLY);
100: MatAssemblyEnd(*subMat, MAT_FINAL_ASSEMBLY);
102: /* deallocate temporary data */
103: PetscFree3(newbRow, newbCol, vals);
104: PetscFree(commRankMap);
105: PetscFree(garrayCMap);
106: if (scall == MAT_INITIAL_MATRIX) PetscFree(nnz);
107: return 0;
108: }