Date: 2021-03-03T22:26:48+00:00

Actual source code: sliced.c
petsc-3.14.5 2021-03-03
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      1: #include <petscdmsliced.h>
      2: #include <petscmat.h>
      3: #include <petsc/private/dmimpl.h>

      5: /* CSR storage of the nonzero structure of a bs*bs matrix */
      6: typedef struct {
      7:   PetscInt bs,nz,*i,*j;
      8: } DMSlicedBlockFills;

     10: typedef struct  {
     11:   PetscInt           bs,n,N,Nghosts,*ghosts;
     12:   PetscInt           d_nz,o_nz,*d_nnz,*o_nnz;
     13:   DMSlicedBlockFills *dfill,*ofill;
     14: } DM_Sliced;

     16: PetscErrorCode  DMCreateMatrix_Sliced(DM dm, Mat *J)
     17: {
     18:   PetscErrorCode         ierr;
     19:   PetscInt               *globals,*sd_nnz,*so_nnz,rstart,bs,i;
     20:   ISLocalToGlobalMapping lmap;
     21:   void                   (*aij)(void) = NULL;
     22:   DM_Sliced              *slice = (DM_Sliced*)dm->data;

     25:   bs   = slice->bs;
     26:   MatCreate(PetscObjectComm((PetscObject)dm),J);
     27:   MatSetSizes(*J,slice->n*bs,slice->n*bs,PETSC_DETERMINE,PETSC_DETERMINE);
     28:   MatSetBlockSize(*J,bs);
     29:   MatSetType(*J,dm->mattype);
     30:   MatSeqBAIJSetPreallocation(*J,bs,slice->d_nz,slice->d_nnz);
     31:   MatMPIBAIJSetPreallocation(*J,bs,slice->d_nz,slice->d_nnz,slice->o_nz,slice->o_nnz);
     32:   /* In general, we have to do extra work to preallocate for scalar (AIJ) matrices so we check whether it will do any
     33:   * good before going on with it. */
     34:   PetscObjectQueryFunction((PetscObject)*J,"MatMPIAIJSetPreallocation_C",&aij);
     35:   if (!aij) {
     36:     PetscObjectQueryFunction((PetscObject)*J,"MatSeqAIJSetPreallocation_C",&aij);
     37:   }
     38:   if (aij) {
     39:     if (bs == 1) {
     40:       MatSeqAIJSetPreallocation(*J,slice->d_nz,slice->d_nnz);
     41:       MatMPIAIJSetPreallocation(*J,slice->d_nz,slice->d_nnz,slice->o_nz,slice->o_nnz);
     42:     } else if (!slice->d_nnz) {
     43:       MatSeqAIJSetPreallocation(*J,slice->d_nz*bs,NULL);
     44:       MatMPIAIJSetPreallocation(*J,slice->d_nz*bs,NULL,slice->o_nz*bs,NULL);
     45:     } else {
     46:       /* The user has provided preallocation per block-row, convert it to per scalar-row respecting DMSlicedSetBlockFills() if applicable */
     47:       PetscMalloc2(slice->n*bs,&sd_nnz,(!!slice->o_nnz)*slice->n*bs,&so_nnz);
     48:       for (i=0; i<slice->n*bs; i++) {
     49:         sd_nnz[i] = (slice->d_nnz[i/bs]-1) * (slice->ofill ? slice->ofill->i[i%bs+1]-slice->ofill->i[i%bs] : bs)
     50:                                            + (slice->dfill ? slice->dfill->i[i%bs+1]-slice->dfill->i[i%bs] : bs);
     51:         if (so_nnz) {
     52:           so_nnz[i] = slice->o_nnz[i/bs] * (slice->ofill ? slice->ofill->i[i%bs+1]-slice->ofill->i[i%bs] : bs);
     53:         }
     54:       }
     55:       MatSeqAIJSetPreallocation(*J,slice->d_nz*bs,sd_nnz);
     56:       MatMPIAIJSetPreallocation(*J,slice->d_nz*bs,sd_nnz,slice->o_nz*bs,so_nnz);
     57:       PetscFree2(sd_nnz,so_nnz);
     58:     }
     59:   }

     61:   /* Set up the local to global map.  For the scalar map, we have to translate to entry-wise indexing instead of block-wise. */
     62:   PetscMalloc1(slice->n+slice->Nghosts,&globals);
     63:   MatGetOwnershipRange(*J,&rstart,NULL);
     64:   for (i=0; i<slice->n; i++) globals[i] = rstart/bs + i;

     66:   for (i=0; i<slice->Nghosts; i++) {
     67:     globals[slice->n+i] = slice->ghosts[i];
     68:   }
     69:   ISLocalToGlobalMappingCreate(PETSC_COMM_SELF,bs,slice->n+slice->Nghosts,globals,PETSC_OWN_POINTER,&lmap);
     70:   MatSetLocalToGlobalMapping(*J,lmap,lmap);
     71:   ISLocalToGlobalMappingDestroy(&lmap);
     72:   MatSetDM(*J,dm);
     73:   return(0);
     74: }

     76: /*@C
     77:     DMSlicedSetGhosts - Sets the global indices of other processes elements that will
     78:       be ghosts on this process

     80:     Not Collective

     82:     Input Parameters:
     83: +    slice - the DM object
     84: .    bs - block size
     85: .    nlocal - number of local (owned, non-ghost) blocks
     86: .    Nghosts - number of ghost blocks on this process
     87: -    ghosts - global indices of each ghost block

     89:     Level: advanced

     91: .seealso DMDestroy(), DMCreateGlobalVector()

     93: @*/
     94: PetscErrorCode  DMSlicedSetGhosts(DM dm,PetscInt bs,PetscInt nlocal,PetscInt Nghosts,const PetscInt ghosts[])
     95: {
     97:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    101:   PetscFree(slice->ghosts);
    102:   PetscMalloc1(Nghosts,&slice->ghosts);
    103:   PetscArraycpy(slice->ghosts,ghosts,Nghosts);
    104:   slice->bs      = bs;
    105:   slice->n       = nlocal;
    106:   slice->Nghosts = Nghosts;
    107:   return(0);
    108: }

    110: /*@C
    111:     DMSlicedSetPreallocation - sets the matrix memory preallocation for matrices computed by DMSliced

    113:     Not Collective

    115:     Input Parameters:
    116: +    slice - the DM object
    117: .    d_nz  - number of block nonzeros per block row in diagonal portion of local
    118:            submatrix  (same for all local rows)
    119: .    d_nnz - array containing the number of block nonzeros in the various block rows
    120:            of the in diagonal portion of the local (possibly different for each block
    121:            row) or NULL.
    122: .    o_nz  - number of block nonzeros per block row in the off-diagonal portion of local
    123:            submatrix (same for all local rows).
    124: -    o_nnz - array containing the number of nonzeros in the various block rows of the
    125:            off-diagonal portion of the local submatrix (possibly different for
    126:            each block row) or NULL.

    128:     Notes:
    129:     See MatMPIBAIJSetPreallocation() for more details on preallocation.  If a scalar matrix (AIJ) is
    130:     obtained with DMSlicedGetMatrix(), the correct preallocation will be set, respecting DMSlicedSetBlockFills().

    132:     Level: advanced

    134: .seealso DMDestroy(), DMCreateGlobalVector(), MatMPIAIJSetPreallocation(),
    135:          MatMPIBAIJSetPreallocation(), DMSlicedGetMatrix(), DMSlicedSetBlockFills()

    137: @*/
    138: PetscErrorCode  DMSlicedSetPreallocation(DM dm,PetscInt d_nz,const PetscInt d_nnz[],PetscInt o_nz,const PetscInt o_nnz[])
    139: {
    140:   DM_Sliced *slice = (DM_Sliced*)dm->data;

    144:   slice->d_nz  = d_nz;
    145:   slice->d_nnz = (PetscInt*)d_nnz;
    146:   slice->o_nz  = o_nz;
    147:   slice->o_nnz = (PetscInt*)o_nnz;
    148:   return(0);
    149: }

    151: static PetscErrorCode DMSlicedSetBlockFills_Private(PetscInt bs,const PetscInt *fill,DMSlicedBlockFills **inf)
    152: {
    153:   PetscErrorCode     ierr;
    154:   PetscInt           i,j,nz,*fi,*fj;
    155:   DMSlicedBlockFills *f;

    159:   if (*inf) {PetscFree3(*inf,(*inf)->i,(*inf)->j);}
    160:   if (!fill) return(0);
    161:   for (i=0,nz=0; i<bs*bs; i++) if (fill[i]) nz++;
    162:   PetscMalloc3(1,&f,bs+1,&fi,nz,&fj);
    163:   f->bs = bs;
    164:   f->nz = nz;
    165:   f->i  = fi;
    166:   f->j  = fj;
    167:   for (i=0,nz=0; i<bs; i++) {
    168:     fi[i] = nz;
    169:     for (j=0; j<bs; j++) if (fill[i*bs+j]) fj[nz++] = j;
    170:   }
    171:   fi[i] = nz;
    172:   *inf  = f;
    173:   return(0);
    174: }

    176: /*@C
    177:     DMSlicedSetBlockFills - Sets the fill pattern in each block for a multi-component problem
    178:     of the matrix returned by DMSlicedGetMatrix().

    180:     Logically Collective on dm

    182:     Input Parameter:
    183: +   sliced - the DM object
    184: .   dfill - the fill pattern in the diagonal block (may be NULL, means use dense block)
    185: -   ofill - the fill pattern in the off-diagonal blocks

    187:     Notes:
    188:     This only makes sense for multicomponent problems using scalar matrix formats (AIJ).
    189:     See DMDASetBlockFills() for example usage.

    191:     Level: advanced

    193: .seealso DMSlicedGetMatrix(), DMDASetBlockFills()
    194: @*/
    195: PetscErrorCode  DMSlicedSetBlockFills(DM dm,const PetscInt *dfill,const PetscInt *ofill)
    196: {
    197:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    202:   DMSlicedSetBlockFills_Private(slice->bs,dfill,&slice->dfill);
    203:   DMSlicedSetBlockFills_Private(slice->bs,ofill,&slice->ofill);
    204:   return(0);
    205: }

    207: static PetscErrorCode  DMDestroy_Sliced(DM dm)
    208: {
    210:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    213:   PetscFree(slice->ghosts);
    214:   if (slice->dfill) {PetscFree3(slice->dfill,slice->dfill->i,slice->dfill->j);}
    215:   if (slice->ofill) {PetscFree3(slice->ofill,slice->ofill->i,slice->ofill->j);}
    216:   /* This was originally freed in DMDestroy(), but that prevents reference counting of backend objects */
    217:   PetscFree(slice);
    218:   return(0);
    219: }

    221: static PetscErrorCode  DMCreateGlobalVector_Sliced(DM dm,Vec *gvec)
    222: {
    224:   DM_Sliced      *slice = (DM_Sliced*)dm->data;

    229:   *gvec = NULL;
    230:   VecCreateGhostBlock(PetscObjectComm((PetscObject)dm),slice->bs,slice->n*slice->bs,PETSC_DETERMINE,slice->Nghosts,slice->ghosts,gvec);
    231:   VecSetDM(*gvec,dm);
    232:   return(0);
    233: }

    235: static PetscErrorCode  DMGlobalToLocalBegin_Sliced(DM da,Vec g,InsertMode mode,Vec l)
    236: {
    238:   PetscBool      flg;

    241:   VecGhostIsLocalForm(g,l,&flg);
    242:   if (!flg) SETERRQ(PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_WRONG,"Local vector is not local form of global vector");
    243:   VecGhostUpdateEnd(g,mode,SCATTER_FORWARD);
    244:   VecGhostUpdateBegin(g,mode,SCATTER_FORWARD);
    245:   return(0);
    246: }

    248: static PetscErrorCode  DMGlobalToLocalEnd_Sliced(DM da,Vec g,InsertMode mode,Vec l)
    249: {
    251:   PetscBool      flg;

    254:   VecGhostIsLocalForm(g,l,&flg);
    255:   if (!flg) SETERRQ(PetscObjectComm((PetscObject)da),PETSC_ERR_ARG_WRONG,"Local vector is not local form of global vector");
    256:   VecGhostUpdateEnd(g,mode,SCATTER_FORWARD);
    257:   return(0);
    258: }

    260: /*MC
    261:    DMSLICED = "sliced" - A DM object that is used to manage data for a general graph. Uses VecCreateGhost() ghosted vectors for storing the fields

    263:    See DMCreateSliced() for details.

    265:   Level: intermediate

    267: .seealso: DMType, DMCOMPOSITE, DMCreateSliced(), DMCreate()
    268: M*/

    270: PETSC_EXTERN PetscErrorCode DMCreate_Sliced(DM p)
    271: {
    273:   DM_Sliced      *slice;

    276:   PetscNewLog(p,&slice);
    277:   p->data = slice;

    279:   p->ops->createglobalvector = DMCreateGlobalVector_Sliced;
    280:   p->ops->creatematrix       = DMCreateMatrix_Sliced;
    281:   p->ops->globaltolocalbegin = DMGlobalToLocalBegin_Sliced;
    282:   p->ops->globaltolocalend   = DMGlobalToLocalEnd_Sliced;
    283:   p->ops->destroy            = DMDestroy_Sliced;
    284:   return(0);
    285: }

    287: /*@C
    288:     DMSlicedCreate - Creates a DM object, used to manage data for a unstructured problem

    290:     Collective

    292:     Input Parameter:
    293: +   comm - the processors that will share the global vector
    294: .   bs - the block size
    295: .   nlocal - number of vector entries on this process
    296: .   Nghosts - number of ghost points needed on this process
    297: .   ghosts - global indices of all ghost points for this process
    298: .   d_nnz - matrix preallocation information representing coupling within this process
    299: -   o_nnz - matrix preallocation information representing coupling between this process and other processes

    301:     Output Parameters:
    302: .   slice - the slice object

    304:     Notes:
    305:         This DM does not support DMCreateLocalVector(), DMGlobalToLocalBegin(), and DMGlobalToLocalEnd() instead one directly uses
    306:         VecGhostGetLocalForm() and VecGhostRestoreLocalForm() to access the local representation and VecGhostUpdateBegin() and VecGhostUpdateEnd() to update
    307:         the ghost points.

    309:         One can use DMGlobalToLocalBegin(), and DMGlobalToLocalEnd() instead of VecGhostUpdateBegin() and VecGhostUpdateEnd().

    311:     Level: advanced

    313: .seealso DMDestroy(), DMCreateGlobalVector(), DMSetType(), DMSLICED, DMSlicedSetGhosts(), DMSlicedSetPreallocation(), VecGhostUpdateBegin(), VecGhostUpdateEnd(),
    314:          VecGhostGetLocalForm(), VecGhostRestoreLocalForm()

    316: @*/
    317: PetscErrorCode  DMSlicedCreate(MPI_Comm comm,PetscInt bs,PetscInt nlocal,PetscInt Nghosts,const PetscInt ghosts[], const PetscInt d_nnz[],const PetscInt o_nnz[],DM *dm)
    318: {

    323:   DMCreate(comm,dm);
    324:   DMSetType(*dm,DMSLICED);
    325:   DMSlicedSetGhosts(*dm,bs,nlocal,Nghosts,ghosts);
    326:   if (d_nnz) {
    327:     DMSlicedSetPreallocation(*dm,0, d_nnz,0,o_nnz);
    328:   }
    329:   return(0);
    330: }