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: }