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++) {
 94:             vals[k1+k*bs] = *aijBvals++;
 95:           }
 96:         }
 97:         MatSetValues(*subMat,bs,newbRow,bs,newbCol,vals,INSERT_VALUES);
 98:       }
 99:     }
100:   }
101:   MatAssemblyBegin(*subMat,MAT_FINAL_ASSEMBLY);
102:   MatAssemblyEnd(*subMat,MAT_FINAL_ASSEMBLY);

104:   /* deallocate temporary data */
105:   PetscFree3(newbRow,newbCol,vals);
106:   PetscFree(commRankMap);
107:   PetscFree(garrayCMap);
108:   if (scall == MAT_INITIAL_MATRIX) {
109:     PetscFree(nnz);
110:   }
111:   return 0;
112: }