Date: 2016-07-24T16:49:03+00:00

Actual source code: vscat.c
petsc-3.7.3 2016-07-24
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      2: /*
      3:      Code for creating scatters between vectors. This file
      4:   includes the code for scattering between sequential vectors and
      5:   some special cases for parallel scatters.
      6: */

      8: #include <petsc/private/isimpl.h>
      9: #include <petsc/private/vecimpl.h>    /*I   "petscvec.h"    I*/

     11: #if defined(PETSC_HAVE_CUSP)
     12: PETSC_INTERN PetscErrorCode VecScatterCUSPIndicesCreate_PtoP(PetscInt,PetscInt*,PetscInt,PetscInt*,PetscCUSPIndices*);
     13: PETSC_INTERN PetscErrorCode VecScatterCUSPIndicesCreate_StoS(PetscInt,PetscInt,PetscInt,PetscInt,PetscInt,PetscInt*,PetscInt*,PetscCUSPIndices*);
     14: PETSC_INTERN PetscErrorCode VecScatterCUSPIndicesDestroy(PetscCUSPIndices*);
     15: PETSC_INTERN PetscErrorCode VecScatterCUSP_StoS(Vec,Vec,PetscCUSPIndices,InsertMode,ScatterMode);
     16: #elif defined(PETSC_HAVE_VECCUDA)
     17: PETSC_INTERN PetscErrorCode VecScatterCUDAIndicesCreate_PtoP(PetscInt,PetscInt*,PetscInt,PetscInt*,PetscCUDAIndices*);
     18: PETSC_INTERN PetscErrorCode VecScatterCUDAIndicesCreate_StoS(PetscInt,PetscInt,PetscInt,PetscInt,PetscInt,PetscInt*,PetscInt*,PetscCUDAIndices*);
     19: PETSC_INTERN PetscErrorCode VecScatterCUDAIndicesDestroy(PetscCUDAIndices*);
     20: PETSC_INTERN PetscErrorCode VecScatterCUDA_StoS(Vec,Vec,PetscCUDAIndices,InsertMode,ScatterMode);
     21: #endif

     23: /* Logging support */
     24: PetscClassId VEC_SCATTER_CLASSID;

     26: #if defined(PETSC_USE_DEBUG)
     27: /*
     28:      Checks if any indices are less than zero and generates an error
     29: */
     32: static PetscErrorCode VecScatterCheckIndices_Private(PetscInt nmax,PetscInt n,const PetscInt *idx)
     33: {
     34:   PetscInt i;

     37:   for (i=0; i<n; i++) {
     38:     if (idx[i] < 0)     SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Negative index %D at %D location",idx[i],i);
     39:     if (idx[i] >= nmax) SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Index %D at %D location greater than max %D",idx[i],i,nmax);
     40:   }
     41:   return(0);
     42: }
     43: #endif

     45: /*
     46:       This is special scatter code for when the entire parallel vector is copied to each processor.

     48:    This code was written by Cameron Cooper, Occidental College, Fall 1995,
     49:    will working at ANL as a SERS student.
     50: */
     53: PetscErrorCode VecScatterBegin_MPI_ToAll(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
     54: {
     56:   PetscInt       yy_n,xx_n;
     57:   PetscScalar    *xv,*yv;

     60:   VecGetLocalSize(y,&yy_n);
     61:   VecGetLocalSize(x,&xx_n);
     62:   VecGetArrayPair(x,y,&xv,&yv);

     64:   if (mode & SCATTER_REVERSE) {
     65:     PetscScalar          *xvt,*xvt2;
     66:     VecScatter_MPI_ToAll *scat = (VecScatter_MPI_ToAll*)ctx->todata;
     67:     PetscInt             i;
     68:     PetscMPIInt          *disply = scat->displx;

     70:     if (addv == INSERT_VALUES) {
     71:       PetscInt rstart,rend;
     72:       /*
     73:          copy the correct part of the local vector into the local storage of
     74:          the MPI one.  Note: this operation only makes sense if all the local
     75:          vectors have the same values
     76:       */
     77:       VecGetOwnershipRange(y,&rstart,&rend);
     78:       PetscMemcpy(yv,xv+rstart,yy_n*sizeof(PetscScalar));
     79:     } else {
     80:       MPI_Comm    comm;
     81:       PetscMPIInt rank;
     82:       PetscObjectGetComm((PetscObject)y,&comm);
     83:       MPI_Comm_rank(comm,&rank);
     84:       if (scat->work1) xvt = scat->work1;
     85:       else {
     86:         PetscMalloc1(xx_n,&xvt);
     87:         scat->work1 = xvt;
     88:       }
     89:       if (!rank) { /* I am the zeroth processor, values are accumulated here */
     90:         if   (scat->work2) xvt2 = scat->work2;
     91:         else {
     92:           PetscMalloc1(xx_n,&xvt2);
     93:           scat->work2 = xvt2;
     94:         }
     95:         MPI_Gatherv(yv,yy_n,MPIU_SCALAR,xvt2,scat->count,disply,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
     96:         MPI_Reduce(xv,xvt,xx_n,MPIU_SCALAR,MPIU_SUM,0,PetscObjectComm((PetscObject)ctx));
     97:         if (addv == ADD_VALUES) {
     98:           for (i=0; i<xx_n; i++) xvt[i] += xvt2[i];
     99: #if !defined(PETSC_USE_COMPLEX)
    100:         } else if (addv == MAX_VALUES) {
    101:           for (i=0; i<xx_n; i++) xvt[i] = PetscMax(xvt[i],xvt2[i]);
    102: #endif
    103:         } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    104:         MPI_Scatterv(xvt,scat->count,disply,MPIU_SCALAR,yv,yy_n,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
    105:       } else {
    106:         MPI_Gatherv(yv,yy_n,MPIU_SCALAR,0, 0,0,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
    107:         MPI_Reduce(xv,xvt,xx_n,MPIU_SCALAR,MPIU_SUM,0,PetscObjectComm((PetscObject)ctx));
    108:         MPI_Scatterv(0,scat->count,disply,MPIU_SCALAR,yv,yy_n,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
    109:       }
    110:     }
    111:   } else {
    112:     PetscScalar          *yvt;
    113:     VecScatter_MPI_ToAll *scat = (VecScatter_MPI_ToAll*)ctx->todata;
    114:     PetscInt             i;
    115:     PetscMPIInt          *displx = scat->displx;

    117:     if (addv == INSERT_VALUES) {
    118:       MPI_Allgatherv(xv,xx_n,MPIU_SCALAR,yv,scat->count,displx,MPIU_SCALAR,PetscObjectComm((PetscObject)ctx));
    119:     } else {
    120:       if (scat->work1) yvt = scat->work1;
    121:       else {
    122:         PetscMalloc1(yy_n,&yvt);
    123:         scat->work1 = yvt;
    124:       }
    125:       MPI_Allgatherv(xv,xx_n,MPIU_SCALAR,yvt,scat->count,displx,MPIU_SCALAR,PetscObjectComm((PetscObject)ctx));
    126:       if (addv == ADD_VALUES) {
    127:         for (i=0; i<yy_n; i++) yv[i] += yvt[i];
    128: #if !defined(PETSC_USE_COMPLEX)
    129:       } else if (addv == MAX_VALUES) {
    130:         for (i=0; i<yy_n; i++) yv[i] = PetscMax(yv[i],yvt[i]);
    131: #endif
    132:       } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    133:     }
    134:   }
    135:   VecRestoreArrayPair(x,y,&xv,&yv);
    136:   return(0);
    137: }

    141: PetscErrorCode VecScatterView_MPI_ToAll(VecScatter in,PetscViewer viewer)
    142: {
    144:   PetscBool      isascii;

    147:   PetscObjectTypeCompare((PetscObject)in,PETSCVIEWERASCII,&isascii);
    148:   if (isascii) {
    149:     PetscViewerASCIIPrintf(viewer,"Entire parallel vector is copied to each process\n");
    150:   }
    151:   return(0);
    152: }

    154: /*
    155:       This is special scatter code for when the entire parallel vector is  copied to processor 0.

    157: */
    160: PetscErrorCode VecScatterBegin_MPI_ToOne(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    161: {
    162:   PetscErrorCode    ierr;
    163:   PetscMPIInt       rank;
    164:   PetscInt          yy_n,xx_n;
    165:   PetscScalar       *yv;
    166:   const PetscScalar *xv;
    167:   MPI_Comm          comm;

    170:   VecGetLocalSize(y,&yy_n);
    171:   VecGetLocalSize(x,&xx_n);
    172:   VecGetArrayRead(x,&xv);
    173:   VecGetArray(y,&yv);

    175:   PetscObjectGetComm((PetscObject)x,&comm);
    176:   MPI_Comm_rank(comm,&rank);

    178:   /* --------  Reverse scatter; spread from processor 0 to other processors */
    179:   if (mode & SCATTER_REVERSE) {
    180:     PetscScalar          *yvt;
    181:     VecScatter_MPI_ToAll *scat = (VecScatter_MPI_ToAll*)ctx->todata;
    182:     PetscInt             i;
    183:     PetscMPIInt          *disply = scat->displx;

    185:     if (addv == INSERT_VALUES) {
    186:       MPI_Scatterv((PetscScalar*)xv,scat->count,disply,MPIU_SCALAR,yv,yy_n,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
    187:     } else {
    188:       if (scat->work2) yvt = scat->work2;
    189:       else {
    190:         PetscMalloc1(xx_n,&yvt);
    191:         scat->work2 = yvt;
    192:       }
    193:       MPI_Scatterv((PetscScalar*)xv,scat->count,disply,MPIU_SCALAR,yvt,yy_n,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
    194:       if (addv == ADD_VALUES) {
    195:         for (i=0; i<yy_n; i++) yv[i] += yvt[i];
    196: #if !defined(PETSC_USE_COMPLEX)
    197:       } else if (addv == MAX_VALUES) {
    198:         for (i=0; i<yy_n; i++) yv[i] = PetscMax(yv[i],yvt[i]);
    199: #endif
    200:       } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    201:     }
    202:   /* ---------  Forward scatter; gather all values onto processor 0 */
    203:   } else {
    204:     PetscScalar          *yvt  = 0;
    205:     VecScatter_MPI_ToAll *scat = (VecScatter_MPI_ToAll*)ctx->todata;
    206:     PetscInt             i;
    207:     PetscMPIInt          *displx = scat->displx;

    209:     if (addv == INSERT_VALUES) {
    210:       MPI_Gatherv((PetscScalar*)xv,xx_n,MPIU_SCALAR,yv,scat->count,displx,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
    211:     } else {
    212:       if (!rank) {
    213:         if (scat->work1) yvt = scat->work1;
    214:         else {
    215:           PetscMalloc1(yy_n,&yvt);
    216:           scat->work1 = yvt;
    217:         }
    218:       }
    219:       MPI_Gatherv((PetscScalar*)xv,xx_n,MPIU_SCALAR,yvt,scat->count,displx,MPIU_SCALAR,0,PetscObjectComm((PetscObject)ctx));
    220:       if (!rank) {
    221:         if (addv == ADD_VALUES) {
    222:           for (i=0; i<yy_n; i++) yv[i] += yvt[i];
    223: #if !defined(PETSC_USE_COMPLEX)
    224:         } else if (addv == MAX_VALUES) {
    225:           for (i=0; i<yy_n; i++) yv[i] = PetscMax(yv[i],yvt[i]);
    226: #endif
    227:         }  else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    228:       }
    229:     }
    230:   }
    231:   VecRestoreArrayRead(x,&xv);
    232:   VecRestoreArray(y,&yv);
    233:   return(0);
    234: }

    236: /*
    237:        The follow to are used for both VecScatterBegin_MPI_ToAll() and VecScatterBegin_MPI_ToOne()
    238: */
    241: PetscErrorCode VecScatterDestroy_MPI_ToAll(VecScatter ctx)
    242: {
    243:   VecScatter_MPI_ToAll *scat = (VecScatter_MPI_ToAll*)ctx->todata;
    244:   PetscErrorCode       ierr;

    247:   PetscFree(scat->work1);
    248:   PetscFree(scat->work2);
    249:   PetscFree3(ctx->todata,scat->count,scat->displx);
    250:   return(0);
    251: }

    255: PetscErrorCode VecScatterDestroy_SGToSG(VecScatter ctx)
    256: {

    260:   PetscFree2(((VecScatter_Seq_General*)ctx->todata)->vslots,((VecScatter_Seq_General*)ctx->fromdata)->vslots);
    261:   PetscFree2(ctx->todata,ctx->fromdata);
    262:   return(0);
    263: }

    267: PetscErrorCode VecScatterDestroy_SGToSS(VecScatter ctx)
    268: {

    272:   PetscFree(((VecScatter_Seq_General*)ctx->fromdata)->vslots);
    273:   PetscFree2(ctx->todata,ctx->fromdata);
    274:   return(0);
    275: }

    279: PetscErrorCode VecScatterDestroy_SSToSG(VecScatter ctx)
    280: {

    284:   PetscFree(((VecScatter_Seq_General*)ctx->todata)->vslots);
    285:   PetscFree2(ctx->todata,ctx->fromdata);
    286:   return(0);
    287: }

    291: PetscErrorCode VecScatterDestroy_SSToSS(VecScatter ctx)
    292: {

    296:   PetscFree2(ctx->todata,ctx->fromdata);
    297:   return(0);
    298: }

    300: /* -------------------------------------------------------------------------*/
    303: PetscErrorCode VecScatterCopy_MPI_ToAll(VecScatter in,VecScatter out)
    304: {
    305:   VecScatter_MPI_ToAll *in_to = (VecScatter_MPI_ToAll*)in->todata,*sto;
    306:   PetscErrorCode       ierr;
    307:   PetscMPIInt          size,*count,*displx;
    308:   PetscInt             i;

    311:   out->ops->begin   = in->ops->begin;
    312:   out->ops->end     = in->ops->end;
    313:   out->ops->copy    = in->ops->copy;
    314:   out->ops->destroy = in->ops->destroy;
    315:   out->ops->view    = in->ops->view;

    317:   MPI_Comm_size(PetscObjectComm((PetscObject)out),&size);
    318:   PetscMalloc3(1,&sto,size,&count,size,&displx);
    319:   sto->type   = in_to->type;
    320:   sto->count  = count;
    321:   sto->displx = displx;
    322:   for (i=0; i<size; i++) {
    323:     sto->count[i]  = in_to->count[i];
    324:     sto->displx[i] = in_to->displx[i];
    325:   }
    326:   sto->work1    = 0;
    327:   sto->work2    = 0;
    328:   out->todata   = (void*)sto;
    329:   out->fromdata = (void*)0;
    330:   return(0);
    331: }

    333: /* --------------------------------------------------------------------------------------*/
    334: /*
    335:         Scatter: sequential general to sequential general
    336: */
    339: PetscErrorCode VecScatterBegin_SGToSG(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    340: {
    341:   VecScatter_Seq_General *gen_to   = (VecScatter_Seq_General*)ctx->todata;
    342:   VecScatter_Seq_General *gen_from = (VecScatter_Seq_General*)ctx->fromdata;
    343:   PetscErrorCode         ierr;
    344:   PetscInt               i,n = gen_from->n,*fslots,*tslots;
    345:   PetscScalar            *xv,*yv;

    348: #if defined(PETSC_HAVE_CUSP)
    349:   if (x->valid_GPU_array == PETSC_CUSP_GPU) {
    350:     /* create the scatter indices if not done already */
    351:     if (!ctx->spptr) {
    352:       PetscInt tofirst = 0,tostep = 0,fromfirst = 0,fromstep = 0;
    353:       fslots = gen_from->vslots;
    354:       tslots = gen_to->vslots;
    355:       VecScatterCUSPIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUSPIndices*)&(ctx->spptr));
    356:     }
    357:     /* next do the scatter */
    358:     VecScatterCUSP_StoS(x,y,(PetscCUSPIndices)ctx->spptr,addv,mode);
    359:     return(0);
    360:   }
    361: #elif defined(PETSC_HAVE_VECCUDA)
    362:   if (x->valid_GPU_array == PETSC_CUDA_GPU) {
    363:     /* create the scatter indices if not done already */
    364:     if (!ctx->spptr) {
    365:       PetscInt tofirst = 0,tostep = 0,fromfirst = 0,fromstep = 0;
    366:       fslots = gen_from->vslots;
    367:       tslots = gen_to->vslots;
    368:       VecScatterCUDAIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUDAIndices*)&(ctx->spptr));
    369:     }
    370:     /* next do the scatter */
    371:     VecScatterCUDA_StoS(x,y,(PetscCUDAIndices)ctx->spptr,addv,mode);
    372:     return(0);
    373:   }
    374: #endif

    376:   VecGetArrayPair(x,y,&xv,&yv);
    377:   if (mode & SCATTER_REVERSE) {
    378:     gen_to   = (VecScatter_Seq_General*)ctx->fromdata;
    379:     gen_from = (VecScatter_Seq_General*)ctx->todata;
    380:   }
    381:   fslots = gen_from->vslots;
    382:   tslots = gen_to->vslots;

    384:   if (addv == INSERT_VALUES) {
    385:     for (i=0; i<n; i++) yv[tslots[i]]  = xv[fslots[i]];
    386:   } else if (addv == ADD_VALUES) {
    387:     for (i=0; i<n; i++) yv[tslots[i]] += xv[fslots[i]];
    388: #if !defined(PETSC_USE_COMPLEX)
    389:   } else if (addv == MAX_VALUES) {
    390:     for (i=0; i<n; i++) yv[tslots[i]] = PetscMax(yv[tslots[i]],xv[fslots[i]]);
    391: #endif
    392:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    393:   VecRestoreArrayPair(x,y,&xv,&yv);
    394:   return(0);
    395: }

    397: /*
    398:     Scatter: sequential general to sequential stride 1
    399: */
    402: PetscErrorCode VecScatterBegin_SGToSS_Stride1(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    403: {
    404:   VecScatter_Seq_Stride  *gen_to   = (VecScatter_Seq_Stride*)ctx->todata;
    405:   VecScatter_Seq_General *gen_from = (VecScatter_Seq_General*)ctx->fromdata;
    406:   PetscInt               i,n = gen_from->n,*fslots = gen_from->vslots;
    407:   PetscErrorCode         ierr;
    408:   PetscInt               first = gen_to->first;
    409:   PetscScalar            *xv,*yv;

    412: #if defined(PETSC_HAVE_CUSP)
    413:   if (x->valid_GPU_array == PETSC_CUSP_GPU) {
    414:     /* create the scatter indices if not done already */
    415:     if (!ctx->spptr) {
    416:       PetscInt tofirst = first,tostep = 1,fromfirst = 0,fromstep = 0;
    417:       PetscInt *tslots = 0;
    418:       VecScatterCUSPIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUSPIndices*)&(ctx->spptr));
    419:     }
    420:     /* next do the scatter */
    421:     VecScatterCUSP_StoS(x,y,(PetscCUSPIndices)ctx->spptr,addv,mode);
    422:     return(0);
    423:   }
    424: #elif defined(PETSC_HAVE_VECCUDA)
    425:   if (x->valid_GPU_array == PETSC_CUDA_GPU) {
    426:     /* create the scatter indices if not done already */
    427:     if (!ctx->spptr) {
    428:       PetscInt tofirst = first,tostep = 1,fromfirst = 0,fromstep = 0;
    429:       PetscInt *tslots = 0;
    430:       VecScatterCUDAIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUDAIndices*)&(ctx->spptr));
    431:     }
    432:     /* next do the scatter */
    433:     VecScatterCUDA_StoS(x,y,(PetscCUDAIndices)ctx->spptr,addv,mode);
    434:     return(0);
    435:   }
    436: #endif

    438:   VecGetArrayPair(x,y,&xv,&yv);
    439:   if (mode & SCATTER_REVERSE) {
    440:     xv += first;
    441:     if (addv == INSERT_VALUES) {
    442:       for (i=0; i<n; i++) yv[fslots[i]] = xv[i];
    443:     } else if (addv == ADD_VALUES) {
    444:       for (i=0; i<n; i++) yv[fslots[i]] += xv[i];
    445: #if !defined(PETSC_USE_COMPLEX)
    446:     } else if (addv == MAX_VALUES) {
    447:       for (i=0; i<n; i++) yv[fslots[i]] = PetscMax(yv[fslots[i]],xv[i]);
    448: #endif
    449:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    450:   } else {
    451:     yv += first;
    452:     if (addv == INSERT_VALUES) {
    453:       for (i=0; i<n; i++) yv[i] = xv[fslots[i]];
    454:     } else if (addv == ADD_VALUES) {
    455:       for (i=0; i<n; i++) yv[i] += xv[fslots[i]];
    456: #if !defined(PETSC_USE_COMPLEX)
    457:     } else if (addv == MAX_VALUES) {
    458:       for (i=0; i<n; i++) yv[i] = PetscMax(yv[i],xv[fslots[i]]);
    459: #endif
    460:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    461:   }
    462:   VecRestoreArrayPair(x,y,&xv,&yv);
    463:   return(0);
    464: }

    466: /*
    467:    Scatter: sequential general to sequential stride
    468: */
    471: PetscErrorCode VecScatterBegin_SGToSS(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    472: {
    473:   VecScatter_Seq_Stride  *gen_to   = (VecScatter_Seq_Stride*)ctx->todata;
    474:   VecScatter_Seq_General *gen_from = (VecScatter_Seq_General*)ctx->fromdata;
    475:   PetscInt               i,n = gen_from->n,*fslots = gen_from->vslots;
    476:   PetscErrorCode         ierr;
    477:   PetscInt               first = gen_to->first,step = gen_to->step;
    478:   PetscScalar            *xv,*yv;

    481: #if defined(PETSC_HAVE_CUSP)
    482:   if (x->valid_GPU_array == PETSC_CUSP_GPU) {
    483:     /* create the scatter indices if not done already */
    484:     if (!ctx->spptr) {
    485:       PetscInt tofirst = first,tostep = step,fromfirst = 0,fromstep = 0;
    486:       PetscInt * tslots = 0;
    487:       VecScatterCUSPIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUSPIndices*)&(ctx->spptr));
    488:     }
    489:     /* next do the scatter */
    490:     VecScatterCUSP_StoS(x,y,(PetscCUSPIndices)ctx->spptr,addv,mode);
    491:     return(0);
    492:   }
    493: #elif defined(PETSC_HAVE_VECCUDA)
    494:   if (x->valid_GPU_array == PETSC_CUDA_GPU) {
    495:     /* create the scatter indices if not done already */
    496:     if (!ctx->spptr) {
    497:       PetscInt tofirst = first,tostep = step,fromfirst = 0,fromstep = 0;
    498:       PetscInt * tslots = 0;
    499:       VecScatterCUDAIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUDAIndices*)&(ctx->spptr));
    500:     }
    501:     /* next do the scatter */
    502:     VecScatterCUDA_StoS(x,y,(PetscCUDAIndices)ctx->spptr,addv,mode);
    503:     return(0);
    504:   }
    505: #endif

    507:   VecGetArrayPair(x,y,&xv,&yv);
    508:   if (mode & SCATTER_REVERSE) {
    509:     if (addv == INSERT_VALUES) {
    510:       for (i=0; i<n; i++) yv[fslots[i]] = xv[first + i*step];
    511:     } else if (addv == ADD_VALUES) {
    512:       for (i=0; i<n; i++) yv[fslots[i]] += xv[first + i*step];
    513: #if !defined(PETSC_USE_COMPLEX)
    514:     } else if (addv == MAX_VALUES) {
    515:       for (i=0; i<n; i++) yv[fslots[i]] = PetscMax(yv[fslots[i]],xv[first + i*step]);
    516: #endif
    517:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    518:   } else {
    519:     if (addv == INSERT_VALUES) {
    520:       for (i=0; i<n; i++) yv[first + i*step] = xv[fslots[i]];
    521:     } else if (addv == ADD_VALUES) {
    522:       for (i=0; i<n; i++) yv[first + i*step] += xv[fslots[i]];
    523: #if !defined(PETSC_USE_COMPLEX)
    524:     } else if (addv == MAX_VALUES) {
    525:       for (i=0; i<n; i++) yv[first + i*step] = PetscMax(yv[first + i*step],xv[fslots[i]]);
    526: #endif
    527:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    528:   }
    529:   VecRestoreArrayPair(x,y,&xv,&yv);
    530:   return(0);
    531: }

    533: /*
    534:     Scatter: sequential stride 1 to sequential general
    535: */
    538: PetscErrorCode VecScatterBegin_SSToSG_Stride1(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    539: {
    540:   VecScatter_Seq_Stride  *gen_from = (VecScatter_Seq_Stride*)ctx->fromdata;
    541:   VecScatter_Seq_General *gen_to   = (VecScatter_Seq_General*)ctx->todata;
    542:   PetscInt               i,n = gen_from->n,*tslots = gen_to->vslots;
    543:   PetscErrorCode         ierr;
    544:   PetscInt               first = gen_from->first;
    545:   PetscScalar            *xv,*yv;

    548: #if defined(PETSC_HAVE_CUSP)
    549:   if (x->valid_GPU_array == PETSC_CUSP_GPU) {
    550:     /* create the scatter indices if not done already */
    551:     if (!ctx->spptr) {
    552:       PetscInt tofirst = 0,tostep = 0,fromfirst = first,fromstep = 1;
    553:       PetscInt *fslots = 0;
    554:       VecScatterCUSPIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUSPIndices*)&(ctx->spptr));
    555:     }
    556:     /* next do the scatter */
    557:     VecScatterCUSP_StoS(x,y,(PetscCUSPIndices)ctx->spptr,addv,mode);
    558:     return(0);
    559:   }
    560: #elif defined(PETSC_HAVE_VECCUDA)
    561:   if (x->valid_GPU_array == PETSC_CUDA_GPU) {
    562:     /* create the scatter indices if not done already */
    563:     if (!ctx->spptr) {
    564:       PetscInt tofirst = 0,tostep = 0,fromfirst = first,fromstep = 1;
    565:       PetscInt *fslots = 0;
    566:       VecScatterCUDAIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUDAIndices*)&(ctx->spptr));
    567:     }
    568:     /* next do the scatter */
    569:     VecScatterCUDA_StoS(x,y,(PetscCUDAIndices)ctx->spptr,addv,mode);
    570:     return(0);
    571:   }
    572: #endif

    574:   VecGetArrayPair(x,y,&xv,&yv);
    575:   if (mode & SCATTER_REVERSE) {
    576:     yv += first;
    577:     if (addv == INSERT_VALUES) {
    578:       for (i=0; i<n; i++) yv[i] = xv[tslots[i]];
    579:     } else  if (addv == ADD_VALUES) {
    580:       for (i=0; i<n; i++) yv[i] += xv[tslots[i]];
    581: #if !defined(PETSC_USE_COMPLEX)
    582:     } else  if (addv == MAX_VALUES) {
    583:       for (i=0; i<n; i++) yv[i] = PetscMax(yv[i],xv[tslots[i]]);
    584: #endif
    585:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    586:   } else {
    587:     xv += first;
    588:     if (addv == INSERT_VALUES) {
    589:       for (i=0; i<n; i++) yv[tslots[i]] = xv[i];
    590:     } else  if (addv == ADD_VALUES) {
    591:       for (i=0; i<n; i++) yv[tslots[i]] += xv[i];
    592: #if !defined(PETSC_USE_COMPLEX)
    593:     } else  if (addv == MAX_VALUES) {
    594:       for (i=0; i<n; i++) yv[tslots[i]] = PetscMax(yv[tslots[i]],xv[i]);
    595: #endif
    596:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    597:   }
    598:   VecRestoreArrayPair(x,y,&xv,&yv);
    599:   return(0);
    600: }

    604: /*
    605:    Scatter: sequential stride to sequential general
    606: */
    607: PetscErrorCode VecScatterBegin_SSToSG(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    608: {
    609:   VecScatter_Seq_Stride  *gen_from = (VecScatter_Seq_Stride*)ctx->fromdata;
    610:   VecScatter_Seq_General *gen_to   = (VecScatter_Seq_General*)ctx->todata;
    611:   PetscInt               i,n = gen_from->n,*tslots = gen_to->vslots;
    612:   PetscErrorCode         ierr;
    613:   PetscInt               first = gen_from->first,step = gen_from->step;
    614:   PetscScalar            *xv,*yv;

    617: #if defined(PETSC_HAVE_CUSP)
    618:   if (x->valid_GPU_array == PETSC_CUSP_GPU) {
    619:     /* create the scatter indices if not done already */
    620:     if (!ctx->spptr) {
    621:       PetscInt tofirst = 0,tostep = 0,fromfirst = first,fromstep = step;
    622:       PetscInt *fslots = 0;
    623:       VecScatterCUSPIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUSPIndices*)&(ctx->spptr));
    624:     }
    625:     /* next do the scatter */
    626:     VecScatterCUSP_StoS(x,y,(PetscCUSPIndices)ctx->spptr,addv,mode);
    627:     return(0);
    628:   }
    629: #elif defined(PETSC_HAVE_VECCUDA)
    630:   if (x->valid_GPU_array == PETSC_CUDA_GPU) {
    631:     /* create the scatter indices if not done already */
    632:     if (!ctx->spptr) {
    633:       PetscInt tofirst = 0,tostep = 0,fromfirst = first,fromstep = step;
    634:       PetscInt *fslots = 0;
    635:       VecScatterCUDAIndicesCreate_StoS(n,tofirst,fromfirst,tostep,fromstep,tslots,fslots,(PetscCUDAIndices*)&(ctx->spptr));
    636:     }
    637:     /* next do the scatter */
    638:     VecScatterCUDA_StoS(x,y,(PetscCUDAIndices)ctx->spptr,addv,mode);
    639:     return(0);
    640:   }
    641: #endif

    643:   VecGetArrayPair(x,y,&xv,&yv);
    644:   if (mode & SCATTER_REVERSE) {
    645:     if (addv == INSERT_VALUES) {
    646:       for (i=0; i<n; i++) yv[first + i*step] = xv[tslots[i]];
    647:     } else if (addv == ADD_VALUES) {
    648:       for (i=0; i<n; i++) yv[first + i*step] += xv[tslots[i]];
    649: #if !defined(PETSC_USE_COMPLEX)
    650:     } else if (addv == MAX_VALUES) {
    651:       for (i=0; i<n; i++) yv[first + i*step] = PetscMax(yv[first + i*step],xv[tslots[i]]);
    652: #endif
    653:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    654:   } else {
    655:     if (addv == INSERT_VALUES) {
    656:       for (i=0; i<n; i++) yv[tslots[i]] = xv[first + i*step];
    657:     } else if (addv == ADD_VALUES) {
    658:       for (i=0; i<n; i++) yv[tslots[i]] += xv[first + i*step];
    659: #if !defined(PETSC_USE_COMPLEX)
    660:     } else if (addv == MAX_VALUES) {
    661:       for (i=0; i<n; i++) yv[tslots[i]] = PetscMax(yv[tslots[i]],xv[first + i*step]);
    662: #endif
    663:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    664:   }
    665:   VecRestoreArrayPair(x,y,&xv,&yv);
    666:   return(0);
    667: }

    671: PetscErrorCode VecScatterView_SSToSG(VecScatter in,PetscViewer viewer)
    672: {
    673:   PetscErrorCode         ierr;
    674:   VecScatter_Seq_Stride  *in_from = (VecScatter_Seq_Stride*)in->todata;
    675:   VecScatter_Seq_General *in_to   = (VecScatter_Seq_General*)in->fromdata;
    676:   PetscInt               i;
    677:   PetscBool              isascii;

    680:   PetscObjectTypeCompare((PetscObject)in,PETSCVIEWERASCII,&isascii);
    681:   if (isascii) {
    682:     PetscViewerASCIIPrintf(viewer,"Sequential stride to general scatter\n");
    683:     for (i=0; i<in_to->n; i++) {
    684:       PetscViewerASCIIPrintf(viewer,"%D to %D\n",in_from->first + in_from->step*i,in_to->vslots[i]);
    685:     }
    686:   }
    687:   return(0);
    688: }
    689: /*
    690:      Scatter: sequential stride to sequential stride
    691: */
    694: PetscErrorCode VecScatterBegin_SSToSS(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    695: {
    696:   VecScatter_Seq_Stride *gen_to   = (VecScatter_Seq_Stride*)ctx->todata;
    697:   VecScatter_Seq_Stride *gen_from = (VecScatter_Seq_Stride*)ctx->fromdata;
    698:   PetscInt              i,n = gen_from->n,to_first = gen_to->first,to_step = gen_to->step;
    699:   PetscErrorCode        ierr;
    700:   PetscInt              from_first = gen_from->first,from_step = gen_from->step;
    701:   PetscScalar           *xv,*yv;

    704: #if defined(PETSC_HAVE_CUSP)
    705:   if (x->valid_GPU_array == PETSC_CUSP_GPU) {
    706:     /* create the scatter indices if not done already */
    707:     if (!ctx->spptr) {
    708:       PetscInt *tslots = 0,*fslots = 0;
    709:       VecScatterCUSPIndicesCreate_StoS(n,to_first,from_first,to_step,from_step,tslots,fslots,(PetscCUSPIndices*)&(ctx->spptr));
    710:     }
    711:     /* next do the scatter */
    712:     VecScatterCUSP_StoS(x,y,(PetscCUSPIndices)ctx->spptr,addv,mode);
    713:     return(0);
    714:   }
    715: #elif defined(PETSC_HAVE_VECCUDA)
    716:   if (x->valid_GPU_array == PETSC_CUDA_GPU) {
    717:     /* create the scatter indices if not done already */
    718:     if (!ctx->spptr) {
    719:       PetscInt *tslots = 0,*fslots = 0;
    720:       VecScatterCUDAIndicesCreate_StoS(n,to_first,from_first,to_step,from_step,tslots,fslots,(PetscCUDAIndices*)&(ctx->spptr));
    721:     }
    722:     /* next do the scatter */
    723:     VecScatterCUDA_StoS(x,y,(PetscCUDAIndices)ctx->spptr,addv,mode);
    724:     return(0);
    725:   }
    726: #endif

    728:   VecGetArrayPair(x,y,&xv,&yv);
    729:   if (mode & SCATTER_REVERSE) {
    730:     from_first = gen_to->first;
    731:     to_first   = gen_from->first;
    732:     from_step  = gen_to->step;
    733:     to_step    = gen_from->step;
    734:   }

    736:   if (addv == INSERT_VALUES) {
    737:     if (to_step == 1 && from_step == 1) {
    738:       PetscMemcpy(yv+to_first,xv+from_first,n*sizeof(PetscScalar));
    739:     } else  {
    740:       for (i=0; i<n; i++) yv[to_first + i*to_step] = xv[from_first+i*from_step];
    741:     }
    742:   } else if (addv == ADD_VALUES) {
    743:     if (to_step == 1 && from_step == 1) {
    744:       yv += to_first; xv += from_first;
    745:       for (i=0; i<n; i++) yv[i] += xv[i];
    746:     } else {
    747:       for (i=0; i<n; i++) yv[to_first + i*to_step] += xv[from_first+i*from_step];
    748:     }
    749: #if !defined(PETSC_USE_COMPLEX)
    750:   } else if (addv == MAX_VALUES) {
    751:     if (to_step == 1 && from_step == 1) {
    752:       yv += to_first; xv += from_first;
    753:       for (i=0; i<n; i++) yv[i] = PetscMax(yv[i],xv[i]);
    754:     } else {
    755:       for (i=0; i<n; i++) yv[to_first + i*to_step] = PetscMax(yv[to_first + i*to_step],xv[from_first+i*from_step]);
    756:     }
    757: #endif
    758:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Wrong insert option");
    759:   VecRestoreArrayPair(x,y,&xv,&yv);
    760:   return(0);
    761: }

    763: /* --------------------------------------------------------------------------*/

    768: PetscErrorCode VecScatterCopy_SGToSG(VecScatter in,VecScatter out)
    769: {
    770:   PetscErrorCode         ierr;
    771:   VecScatter_Seq_General *in_to   = (VecScatter_Seq_General*)in->todata,*out_to = NULL;
    772:   VecScatter_Seq_General *in_from = (VecScatter_Seq_General*)in->fromdata,*out_from = NULL;

    775:   out->ops->begin   = in->ops->begin;
    776:   out->ops->end     = in->ops->end;
    777:   out->ops->copy    = in->ops->copy;
    778:   out->ops->destroy = in->ops->destroy;
    779:   out->ops->view    = in->ops->view;

    781:   PetscMalloc2(1,&out_to,1,&out_from);
    782:   PetscMalloc2(in_to->n,&out_to->vslots,in_from->n,&out_from->vslots);
    783:   out_to->n                    = in_to->n;
    784:   out_to->type                 = in_to->type;
    785:   out_to->nonmatching_computed = PETSC_FALSE;
    786:   out_to->slots_nonmatching    = 0;
    787:   out_to->is_copy              = PETSC_FALSE;
    788:   PetscMemcpy(out_to->vslots,in_to->vslots,(out_to->n)*sizeof(PetscInt));

    790:   out_from->n                    = in_from->n;
    791:   out_from->type                 = in_from->type;
    792:   out_from->nonmatching_computed = PETSC_FALSE;
    793:   out_from->slots_nonmatching    = 0;
    794:   out_from->is_copy              = PETSC_FALSE;
    795:   PetscMemcpy(out_from->vslots,in_from->vslots,(out_from->n)*sizeof(PetscInt));

    797:   out->todata   = (void*)out_to;
    798:   out->fromdata = (void*)out_from;
    799:   return(0);
    800: }

    804: PetscErrorCode VecScatterView_SGToSG(VecScatter in,PetscViewer viewer)
    805: {
    806:   PetscErrorCode         ierr;
    807:   VecScatter_Seq_General *in_to   = (VecScatter_Seq_General*)in->todata;
    808:   VecScatter_Seq_General *in_from = (VecScatter_Seq_General*)in->fromdata;
    809:   PetscInt               i;
    810:   PetscBool              isascii;

    813:   PetscObjectTypeCompare((PetscObject)in,PETSCVIEWERASCII,&isascii);
    814:   if (isascii) {
    815:     PetscViewerASCIIPrintf(viewer,"Sequential general scatter\n");
    816:     for (i=0; i<in_to->n; i++) {
    817:       PetscViewerASCIIPrintf(viewer,"%D to %D\n",in_from->vslots[i],in_to->vslots[i]);
    818:     }
    819:   }
    820:   return(0);
    821: }

    826: PetscErrorCode VecScatterCopy_SGToSS(VecScatter in,VecScatter out)
    827: {
    828:   PetscErrorCode         ierr;
    829:   VecScatter_Seq_Stride  *in_to   = (VecScatter_Seq_Stride*)in->todata,*out_to = NULL;
    830:   VecScatter_Seq_General *in_from = (VecScatter_Seq_General*)in->fromdata,*out_from = NULL;

    833:   out->ops->begin   = in->ops->begin;
    834:   out->ops->end     = in->ops->end;
    835:   out->ops->copy    = in->ops->copy;
    836:   out->ops->destroy = in->ops->destroy;
    837:   out->ops->view    = in->ops->view;

    839:   PetscMalloc2(1,&out_to,1,&out_from);
    840:   PetscMalloc1(in_from->n,&out_from->vslots);
    841:   out_to->n     = in_to->n;
    842:   out_to->type  = in_to->type;
    843:   out_to->first = in_to->first;
    844:   out_to->step  = in_to->step;
    845:   out_to->type  = in_to->type;

    847:   out_from->n                    = in_from->n;
    848:   out_from->type                 = in_from->type;
    849:   out_from->nonmatching_computed = PETSC_FALSE;
    850:   out_from->slots_nonmatching    = 0;
    851:   out_from->is_copy              = PETSC_FALSE;
    852:   PetscMemcpy(out_from->vslots,in_from->vslots,(out_from->n)*sizeof(PetscInt));

    854:   out->todata   = (void*)out_to;
    855:   out->fromdata = (void*)out_from;
    856:   return(0);
    857: }

    861: PetscErrorCode VecScatterView_SGToSS(VecScatter in,PetscViewer viewer)
    862: {
    863:   PetscErrorCode         ierr;
    864:   VecScatter_Seq_Stride  *in_to   = (VecScatter_Seq_Stride*)in->todata;
    865:   VecScatter_Seq_General *in_from = (VecScatter_Seq_General*)in->fromdata;
    866:   PetscInt               i;
    867:   PetscBool              isascii;

    870:   PetscObjectTypeCompare((PetscObject)in,PETSCVIEWERASCII,&isascii);
    871:   if (isascii) {
    872:     PetscViewerASCIIPrintf(viewer,"Sequential general scatter to stride\n");
    873:     for (i=0; i<in_to->n; i++) {
    874:       PetscViewerASCIIPrintf(viewer,"%D to %D\n",in_from->vslots[i],in_to->first + in_to->step*i);
    875:     }
    876:   }
    877:   return(0);
    878: }

    880: /* --------------------------------------------------------------------------*/
    881: /*
    882:     Scatter: parallel to sequential vector, sequential strides for both.
    883: */
    886: PetscErrorCode VecScatterCopy_SSToSS(VecScatter in,VecScatter out)
    887: {
    888:   VecScatter_Seq_Stride *in_to   = (VecScatter_Seq_Stride*)in->todata,*out_to = NULL;
    889:   VecScatter_Seq_Stride *in_from = (VecScatter_Seq_Stride*)in->fromdata,*out_from = NULL;
    890:   PetscErrorCode        ierr;

    893:   out->ops->begin   = in->ops->begin;
    894:   out->ops->end     = in->ops->end;
    895:   out->ops->copy    = in->ops->copy;
    896:   out->ops->destroy = in->ops->destroy;
    897:   out->ops->view    = in->ops->view;

    899:   PetscMalloc2(1,&out_to,1,&out_from);
    900:   out_to->n       = in_to->n;
    901:   out_to->type    = in_to->type;
    902:   out_to->first   = in_to->first;
    903:   out_to->step    = in_to->step;
    904:   out_to->type    = in_to->type;
    905:   out_from->n     = in_from->n;
    906:   out_from->type  = in_from->type;
    907:   out_from->first = in_from->first;
    908:   out_from->step  = in_from->step;
    909:   out_from->type  = in_from->type;
    910:   out->todata     = (void*)out_to;
    911:   out->fromdata   = (void*)out_from;
    912:   return(0);
    913: }

    917: PetscErrorCode VecScatterView_SSToSS(VecScatter in,PetscViewer viewer)
    918: {
    919:   VecScatter_Seq_Stride *in_to   = (VecScatter_Seq_Stride*)in->todata;
    920:   VecScatter_Seq_Stride *in_from = (VecScatter_Seq_Stride*)in->fromdata;
    921:   PetscErrorCode        ierr;
    922:   PetscBool             isascii;

    925:   PetscObjectTypeCompare((PetscObject)in,PETSCVIEWERASCII,&isascii);
    926:   if (isascii) {
    927:     PetscViewerASCIIPrintf(viewer,"Sequential stride count %D start %D step to start %D stride %D\n",in_to->n,in_to->first,in_to->step,in_from->first,in_from->step);
    928:   }
    929:   return(0);
    930: }

    933: extern PetscErrorCode VecScatterCreate_PtoS(PetscInt,const PetscInt*,PetscInt,const PetscInt*,Vec,Vec,PetscInt,VecScatter);
    934: extern PetscErrorCode VecScatterCreate_PtoP(PetscInt,const PetscInt*,PetscInt,const PetscInt*,Vec,Vec,PetscInt,VecScatter);
    935: extern PetscErrorCode VecScatterCreate_StoP(PetscInt,const PetscInt*,PetscInt,const PetscInt*,Vec,Vec,PetscInt,VecScatter);

    937: /* =======================================================================*/
    938: #define VEC_SEQ_ID 0
    939: #define VEC_MPI_ID 1
    940: #define IS_GENERAL_ID 0
    941: #define IS_STRIDE_ID  1
    942: #define IS_BLOCK_ID   2

    944: /*
    945:    Blocksizes we have optimized scatters for
    946: */

    948: #define VecScatterOptimizedBS(mbs) (2 <= mbs)

    953: PetscErrorCode  VecScatterCreateEmpty(MPI_Comm comm,VecScatter *newctx)
    954: {
    955:   VecScatter     ctx;

    959:   PetscHeaderCreate(ctx,VEC_SCATTER_CLASSID,"VecScatter","VecScatter","Vec",comm,VecScatterDestroy,VecScatterView);
    960:   ctx->inuse               = PETSC_FALSE;
    961:   ctx->beginandendtogether = PETSC_FALSE;
    962:   PetscOptionsGetBool(NULL,NULL,"-vecscatter_merge",&ctx->beginandendtogether,NULL);
    963:   if (ctx->beginandendtogether) {
    964:     PetscInfo(ctx,"Using combined (merged) vector scatter begin and end\n");
    965:   }
    966:   ctx->packtogether = PETSC_FALSE;
    967:   PetscOptionsGetBool(NULL,NULL,"-vecscatter_packtogether",&ctx->packtogether,NULL);
    968:   if (ctx->packtogether) {
    969:     PetscInfo(ctx,"Pack all messages before sending\n");
    970:   }
    971:   *newctx = ctx;
    972:   return(0);
    973: }

    977: /*@C
    978:    VecScatterCreate - Creates a vector scatter context.

    980:    Collective on Vec

    982:    Input Parameters:
    983: +  xin - a vector that defines the shape (parallel data layout of the vector)
    984:          of vectors from which we scatter
    985: .  yin - a vector that defines the shape (parallel data layout of the vector)
    986:          of vectors to which we scatter
    987: .  ix - the indices of xin to scatter (if NULL scatters all values)
    988: -  iy - the indices of yin to hold results (if NULL fills entire vector yin)

    990:    Output Parameter:
    991: .  newctx - location to store the new scatter context

    993:    Options Database Keys: (uses regular MPI_Sends by default)
    994: +  -vecscatter_view         - Prints detail of communications
    995: .  -vecscatter_view ::ascii_info    - Print less details about communication
    996: .  -vecscatter_ssend        - Uses MPI_Ssend_init() instead of MPI_Send_init()
    997: .  -vecscatter_rsend           - use ready receiver mode for MPI sends
    998: .  -vecscatter_merge        - VecScatterBegin() handles all of the communication, VecScatterEnd() is a nop
    999:                               eliminates the chance for overlap of computation and communication
    1000: .  -vecscatter_sendfirst    - Posts sends before receives
    1001: .  -vecscatter_packtogether - Pack all messages before sending, receive all messages before unpacking
    1002: .  -vecscatter_alltoall     - Uses MPI all to all communication for scatter
    1003: .  -vecscatter_window       - Use MPI 2 window operations to move data
    1004: .  -vecscatter_nopack       - Avoid packing to work vector when possible (if used with -vecscatter_alltoall then will use MPI_Alltoallw()
    1005: -  -vecscatter_reproduce    - insure that the order of the communications are done the same for each scatter, this under certain circumstances
    1006:                               will make the results of scatters deterministic when otherwise they are not (it may be slower also).

    1008: $
    1009: $                                                                                    --When packing is used--
    1010: $                               MPI Datatypes (no packing)  sendfirst   merge        packtogether  persistent*
    1011: $                                _nopack                   _sendfirst    _merge      _packtogether                -vecscatter_
    1012: $ ----------------------------------------------------------------------------------------------------------------------------
    1013: $    Message passing    Send       p                           X            X           X         always
    1014: $                      Ssend       p                           X            X           X         always          _ssend
    1015: $                      Rsend       p                        nonsense        X           X         always          _rsend
    1016: $    AlltoAll  v or w              X                        nonsense     always         X         nonsense        _alltoall
    1017: $    MPI_Win                       p                        nonsense        p           p         nonsense        _window
    1018: $
    1019: $   Since persistent sends and receives require a constant memory address they can only be used when data is packed into the work vector
    1020: $   because the in and out array may be different for each call to VecScatterBegin/End().
    1021: $
    1022: $    p indicates possible, but not implemented. X indicates implemented
    1023: $

    1025:     Level: intermediate

    1027:   Notes:
    1028:    In calls to VecScatter() you can use different vectors than the xin and
    1029:    yin you used above; BUT they must have the same parallel data layout, for example,
    1030:    they could be obtained from VecDuplicate().
    1031:    A VecScatter context CANNOT be used in two or more simultaneous scatters;
    1032:    that is you cannot call a second VecScatterBegin() with the same scatter
    1033:    context until the VecScatterEnd() has been called on the first VecScatterBegin().
    1034:    In this case a separate VecScatter is needed for each concurrent scatter.

    1036:    Currently the MPI_Send(), MPI_Ssend() and MPI_Rsend() all use PERSISTENT versions.
    1037:    (this unfortunately requires that the same in and out arrays be used for each use, this
    1038:     is why when not using MPI_alltoallw() we always need to pack the input into the work array before sending
    1039:     and unpack upon receeving instead of using MPI datatypes to avoid the packing/unpacking).

    1041:    Both ix and iy cannot be NULL at the same time.

    1043:    Concepts: scatter^between vectors
    1044:    Concepts: gather^between vectors

    1046: .seealso: VecScatterDestroy(), VecScatterCreateToAll(), VecScatterCreateToZero()
    1047: @*/
    1048: PetscErrorCode  VecScatterCreate(Vec xin,IS ix,Vec yin,IS iy,VecScatter *newctx)
    1049: {
    1050:   VecScatter        ctx;
    1051:   PetscErrorCode    ierr;
    1052:   PetscMPIInt       size;
    1053:   PetscInt          xin_type = VEC_SEQ_ID,yin_type = VEC_SEQ_ID,*range;
    1054:   PetscInt          ix_type  = IS_GENERAL_ID,iy_type = IS_GENERAL_ID;
    1055:   MPI_Comm          comm,ycomm;
    1056:   PetscBool         totalv,ixblock,iyblock,iystride,islocal,cando,flag;
    1057:   IS                tix = 0,tiy = 0;

    1060:   if (!ix && !iy) SETERRQ(PetscObjectComm((PetscObject)xin),PETSC_ERR_SUP,"Cannot pass default in for both input and output indices");

    1062:   /*
    1063:       Determine if the vectors are "parallel", ie. it shares a comm with other processors, or
    1064:       sequential (it does not share a comm). The difference is that parallel vectors treat the
    1065:       index set as providing indices in the global parallel numbering of the vector, with
    1066:       sequential vectors treat the index set as providing indices in the local sequential
    1067:       numbering
    1068:   */
    1069:   PetscObjectGetComm((PetscObject)xin,&comm);
    1070:   MPI_Comm_size(comm,&size);
    1071:   if (size > 1) xin_type = VEC_MPI_ID;

    1073:   PetscObjectGetComm((PetscObject)yin,&ycomm);
    1074:   MPI_Comm_size(ycomm,&size);
    1075:   if (size > 1) {comm = ycomm; yin_type = VEC_MPI_ID;}

    1077:   /* generate the Scatter context */
    1078:   PetscHeaderCreate(ctx,VEC_SCATTER_CLASSID,"VecScatter","VecScatter","Vec",comm,VecScatterDestroy,VecScatterView);
    1079:   ctx->inuse               = PETSC_FALSE;

    1081:   ctx->beginandendtogether = PETSC_FALSE;
    1082:   PetscOptionsGetBool(NULL,NULL,"-vecscatter_merge",&ctx->beginandendtogether,NULL);
    1083:   if (ctx->beginandendtogether) {
    1084:     PetscInfo(ctx,"Using combined (merged) vector scatter begin and end\n");
    1085:   }
    1086:   ctx->packtogether = PETSC_FALSE;
    1087:   PetscOptionsGetBool(NULL,NULL,"-vecscatter_packtogether",&ctx->packtogether,NULL);
    1088:   if (ctx->packtogether) {
    1089:     PetscInfo(ctx,"Pack all messages before sending\n");
    1090:   }

    1092:   VecGetLocalSize(xin,&ctx->from_n);
    1093:   VecGetLocalSize(yin,&ctx->to_n);

    1095:   /*
    1096:       if ix or iy is not included; assume just grabbing entire vector
    1097:   */
    1098:   if (!ix && xin_type == VEC_SEQ_ID) {
    1099:     ISCreateStride(comm,ctx->from_n,0,1,&ix);
    1100:     tix  = ix;
    1101:   } else if (!ix && xin_type == VEC_MPI_ID) {
    1102:     if (yin_type == VEC_MPI_ID) {
    1103:       PetscInt ntmp, low;
    1104:       VecGetLocalSize(xin,&ntmp);
    1105:       VecGetOwnershipRange(xin,&low,NULL);
    1106:       ISCreateStride(comm,ntmp,low,1,&ix);
    1107:     } else {
    1108:       PetscInt Ntmp;
    1109:       VecGetSize(xin,&Ntmp);
    1110:       ISCreateStride(comm,Ntmp,0,1,&ix);
    1111:     }
    1112:     tix = ix;
    1113:   } else if (!ix) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"ix not given, but not Seq or MPI vector");

    1115:   if (!iy && yin_type == VEC_SEQ_ID) {
    1116:     ISCreateStride(comm,ctx->to_n,0,1,&iy);
    1117:     tiy  = iy;
    1118:   } else if (!iy && yin_type == VEC_MPI_ID) {
    1119:     if (xin_type == VEC_MPI_ID) {
    1120:       PetscInt ntmp, low;
    1121:       VecGetLocalSize(yin,&ntmp);
    1122:       VecGetOwnershipRange(yin,&low,NULL);
    1123:       ISCreateStride(comm,ntmp,low,1,&iy);
    1124:     } else {
    1125:       PetscInt Ntmp;
    1126:       VecGetSize(yin,&Ntmp);
    1127:       ISCreateStride(comm,Ntmp,0,1,&iy);
    1128:     }
    1129:     tiy = iy;
    1130:   } else if (!iy) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"iy not given, but not Seq or MPI vector");

    1132:   /*
    1133:      Determine types of index sets
    1134:   */
    1135:   PetscObjectTypeCompare((PetscObject)ix,ISBLOCK,&flag);
    1136:   if (flag) ix_type = IS_BLOCK_ID;
    1137:   PetscObjectTypeCompare((PetscObject)iy,ISBLOCK,&flag);
    1138:   if (flag) iy_type = IS_BLOCK_ID;
    1139:   PetscObjectTypeCompare((PetscObject)ix,ISSTRIDE,&flag);
    1140:   if (flag) ix_type = IS_STRIDE_ID;
    1141:   PetscObjectTypeCompare((PetscObject)iy,ISSTRIDE,&flag);
    1142:   if (flag) iy_type = IS_STRIDE_ID;

    1144:   /* ===========================================================================================================
    1145:         Check for special cases
    1146:      ==========================================================================================================*/
    1147:   /* ---------------------------------------------------------------------------*/
    1148:   if (xin_type == VEC_SEQ_ID && yin_type == VEC_SEQ_ID) {
    1149:     if (ix_type == IS_GENERAL_ID && iy_type == IS_GENERAL_ID) {
    1150:       PetscInt               nx,ny;
    1151:       const PetscInt         *idx,*idy;
    1152:       VecScatter_Seq_General *to = NULL,*from = NULL;

    1154:       ISGetLocalSize(ix,&nx);
    1155:       ISGetLocalSize(iy,&ny);
    1156:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1157:       ISGetIndices(ix,&idx);
    1158:       ISGetIndices(iy,&idy);
    1159:       PetscMalloc2(1,&to,1,&from);
    1160:       PetscMalloc2(nx,&to->vslots,nx,&from->vslots);
    1161:       to->n = nx;
    1162: #if defined(PETSC_USE_DEBUG)
    1163:       VecScatterCheckIndices_Private(ctx->to_n,ny,idy);
    1164: #endif
    1165:       PetscMemcpy(to->vslots,idy,nx*sizeof(PetscInt));
    1166:       from->n = nx;
    1167: #if defined(PETSC_USE_DEBUG)
    1168:       VecScatterCheckIndices_Private(ctx->from_n,nx,idx);
    1169: #endif
    1170:        PetscMemcpy(from->vslots,idx,nx*sizeof(PetscInt));
    1171:       to->type          = VEC_SCATTER_SEQ_GENERAL;
    1172:       from->type        = VEC_SCATTER_SEQ_GENERAL;
    1173:       ctx->todata       = (void*)to;
    1174:       ctx->fromdata     = (void*)from;
    1175:       ctx->ops->begin   = VecScatterBegin_SGToSG;
    1176:       ctx->ops->end     = 0;
    1177:       ctx->ops->destroy = VecScatterDestroy_SGToSG;
    1178:       ctx->ops->copy    = VecScatterCopy_SGToSG;
    1179:       ctx->ops->view    = VecScatterView_SGToSG;
    1180:       PetscInfo(xin,"Special case: sequential vector general scatter\n");
    1181:       goto functionend;
    1182:     } else if (ix_type == IS_STRIDE_ID &&  iy_type == IS_STRIDE_ID) {
    1183:       PetscInt              nx,ny,to_first,to_step,from_first,from_step;
    1184:       VecScatter_Seq_Stride *from8 = NULL,*to8 = NULL;

    1186:       ISGetLocalSize(ix,&nx);
    1187:       ISGetLocalSize(iy,&ny);
    1188:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1189:       ISStrideGetInfo(iy,&to_first,&to_step);
    1190:       ISStrideGetInfo(ix,&from_first,&from_step);
    1191:       PetscMalloc2(1,&to8,1,&from8);
    1192:       to8->n            = nx;
    1193:       to8->first        = to_first;
    1194:       to8->step         = to_step;
    1195:       from8->n          = nx;
    1196:       from8->first      = from_first;
    1197:       from8->step       = from_step;
    1198:       to8->type         = VEC_SCATTER_SEQ_STRIDE;
    1199:       from8->type       = VEC_SCATTER_SEQ_STRIDE;
    1200:       ctx->todata       = (void*)to8;
    1201:       ctx->fromdata     = (void*)from8;
    1202:       ctx->ops->begin   = VecScatterBegin_SSToSS;
    1203:       ctx->ops->end     = 0;
    1204:       ctx->ops->destroy = VecScatterDestroy_SSToSS;
    1205:       ctx->ops->copy    = VecScatterCopy_SSToSS;
    1206:       ctx->ops->view    = VecScatterView_SSToSS;
    1207:       PetscInfo(xin,"Special case: sequential vector stride to stride\n");
    1208:       goto functionend;
    1209:     } else if (ix_type == IS_GENERAL_ID && iy_type == IS_STRIDE_ID) {
    1210:       PetscInt               nx,ny,first,step;
    1211:       const PetscInt         *idx;
    1212:       VecScatter_Seq_General *from9 = NULL;
    1213:       VecScatter_Seq_Stride  *to9   = NULL;

    1215:       ISGetLocalSize(ix,&nx);
    1216:       ISGetIndices(ix,&idx);
    1217:       ISGetLocalSize(iy,&ny);
    1218:       ISStrideGetInfo(iy,&first,&step);
    1219:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1220:       PetscMalloc2(1,&to9,1,&from9);
    1221:       PetscMalloc1(nx,&from9->vslots);
    1222:       to9->n     = nx;
    1223:       to9->first = first;
    1224:       to9->step  = step;
    1225:       from9->n   = nx;
    1226: #if defined(PETSC_USE_DEBUG)
    1227:       VecScatterCheckIndices_Private(ctx->from_n,nx,idx);
    1228: #endif
    1229:       PetscMemcpy(from9->vslots,idx,nx*sizeof(PetscInt));
    1230:       ctx->todata    = (void*)to9; ctx->fromdata = (void*)from9;
    1231:       if (step == 1)  ctx->ops->begin = VecScatterBegin_SGToSS_Stride1;
    1232:       else            ctx->ops->begin = VecScatterBegin_SGToSS;
    1233:       ctx->ops->destroy   = VecScatterDestroy_SGToSS;
    1234:       ctx->ops->end       = 0;
    1235:       ctx->ops->copy      = VecScatterCopy_SGToSS;
    1236:       ctx->ops->view      = VecScatterView_SGToSS;
    1237:       to9->type      = VEC_SCATTER_SEQ_STRIDE;
    1238:       from9->type    = VEC_SCATTER_SEQ_GENERAL;
    1239:       PetscInfo(xin,"Special case: sequential vector general to stride\n");
    1240:       goto functionend;
    1241:     } else if (ix_type == IS_STRIDE_ID && iy_type == IS_GENERAL_ID) {
    1242:       PetscInt               nx,ny,first,step;
    1243:       const PetscInt         *idy;
    1244:       VecScatter_Seq_General *to10 = NULL;
    1245:       VecScatter_Seq_Stride  *from10 = NULL;

    1247:       ISGetLocalSize(ix,&nx);
    1248:       ISGetIndices(iy,&idy);
    1249:       ISGetLocalSize(iy,&ny);
    1250:       ISStrideGetInfo(ix,&first,&step);
    1251:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1252:       PetscMalloc2(1,&to10,1,&from10);
    1253:       PetscMalloc1(nx,&to10->vslots);
    1254:       from10->n     = nx;
    1255:       from10->first = first;
    1256:       from10->step  = step;
    1257:       to10->n       = nx;
    1258: #if defined(PETSC_USE_DEBUG)
    1259:       VecScatterCheckIndices_Private(ctx->to_n,ny,idy);
    1260: #endif
    1261:       PetscMemcpy(to10->vslots,idy,nx*sizeof(PetscInt));
    1262:       ctx->todata   = (void*)to10;
    1263:       ctx->fromdata = (void*)from10;
    1264:       if (step == 1) ctx->ops->begin = VecScatterBegin_SSToSG_Stride1;
    1265:       else           ctx->ops->begin = VecScatterBegin_SSToSG;
    1266:       ctx->ops->destroy = VecScatterDestroy_SSToSG;
    1267:       ctx->ops->end     = 0;
    1268:       ctx->ops->copy    = 0;
    1269:       ctx->ops->view    = VecScatterView_SSToSG;
    1270:       to10->type   = VEC_SCATTER_SEQ_GENERAL;
    1271:       from10->type = VEC_SCATTER_SEQ_STRIDE;
    1272:       PetscInfo(xin,"Special case: sequential vector stride to general\n");
    1273:       goto functionend;
    1274:     } else {
    1275:       PetscInt               nx,ny;
    1276:       const PetscInt         *idx,*idy;
    1277:       VecScatter_Seq_General *to11 = NULL,*from11 = NULL;
    1278:       PetscBool              idnx,idny;

    1280:       ISGetLocalSize(ix,&nx);
    1281:       ISGetLocalSize(iy,&ny);
    1282:       if (nx != ny) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match, in %D out %D",nx,ny);

    1284:       ISIdentity(ix,&idnx);
    1285:       ISIdentity(iy,&idny);
    1286:       if (idnx && idny) {
    1287:         VecScatter_Seq_Stride *to13 = NULL,*from13 = NULL;
    1288:         PetscMalloc2(1,&to13,1,&from13);
    1289:         to13->n       = nx;
    1290:         to13->first   = 0;
    1291:         to13->step    = 1;
    1292:         from13->n     = nx;
    1293:         from13->first = 0;
    1294:         from13->step  = 1;
    1295:         to13->type    = VEC_SCATTER_SEQ_STRIDE;
    1296:         from13->type  = VEC_SCATTER_SEQ_STRIDE;
    1297:         ctx->todata   = (void*)to13;
    1298:         ctx->fromdata = (void*)from13;
    1299:         ctx->ops->begin    = VecScatterBegin_SSToSS;
    1300:         ctx->ops->end      = 0;
    1301:         ctx->ops->destroy  = VecScatterDestroy_SSToSS;
    1302:         ctx->ops->copy     = VecScatterCopy_SSToSS;
    1303:         ctx->ops->view     = VecScatterView_SSToSS;
    1304:         PetscInfo(xin,"Special case: sequential copy\n");
    1305:         goto functionend;
    1306:       }

    1308:       ISGetIndices(iy,&idy);
    1309:       ISGetIndices(ix,&idx);
    1310:       PetscMalloc2(1,&to11,1,&from11);
    1311:       PetscMalloc2(nx,&to11->vslots,nx,&from11->vslots);
    1312:       to11->n = nx;
    1313: #if defined(PETSC_USE_DEBUG)
    1314:       VecScatterCheckIndices_Private(ctx->to_n,ny,idy);
    1315: #endif
    1316:       PetscMemcpy(to11->vslots,idy,nx*sizeof(PetscInt));
    1317:       from11->n = nx;
    1318: #if defined(PETSC_USE_DEBUG)
    1319:       VecScatterCheckIndices_Private(ctx->from_n,nx,idx);
    1320: #endif
    1321:       PetscMemcpy(from11->vslots,idx,nx*sizeof(PetscInt));
    1322:       to11->type        = VEC_SCATTER_SEQ_GENERAL;
    1323:       from11->type      = VEC_SCATTER_SEQ_GENERAL;
    1324:       ctx->todata       = (void*)to11;
    1325:       ctx->fromdata     = (void*)from11;
    1326:       ctx->ops->begin   = VecScatterBegin_SGToSG;
    1327:       ctx->ops->end     = 0;
    1328:       ctx->ops->destroy = VecScatterDestroy_SGToSG;
    1329:       ctx->ops->copy    = VecScatterCopy_SGToSG;
    1330:       ctx->ops->view    = VecScatterView_SGToSG;
    1331:       ISRestoreIndices(ix,&idx);
    1332:       ISRestoreIndices(iy,&idy);
    1333:       PetscInfo(xin,"Sequential vector scatter with block indices\n");
    1334:       goto functionend;
    1335:     }
    1336:   }
    1337:   /* ---------------------------------------------------------------------------*/
    1338:   if (xin_type == VEC_MPI_ID && yin_type == VEC_SEQ_ID) {

    1340:     /* ===========================================================================================================
    1341:           Check for special cases
    1342:        ==========================================================================================================*/
    1343:     islocal = PETSC_FALSE;
    1344:     /* special case extracting (subset of) local portion */
    1345:     if (ix_type == IS_STRIDE_ID && iy_type == IS_STRIDE_ID) {
    1346:       PetscInt              nx,ny,to_first,to_step,from_first,from_step;
    1347:       PetscInt              start,end,min,max;
    1348:       VecScatter_Seq_Stride *from12 = NULL,*to12 = NULL;

    1350:       VecGetOwnershipRange(xin,&start,&end);
    1351:       ISGetLocalSize(ix,&nx);
    1352:       ISStrideGetInfo(ix,&from_first,&from_step);
    1353:       ISGetLocalSize(iy,&ny);
    1354:       ISStrideGetInfo(iy,&to_first,&to_step);
    1355:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1356:       ISGetMinMax(ix,&min,&max);
    1357:       if (min >= start && max < end) islocal = PETSC_TRUE;
    1358:       else islocal = PETSC_FALSE;
    1359:       /* cannot use MPIU_Allreduce() since this call matches with the MPI_Allreduce() in the else statement below */
    1360:       MPI_Allreduce(&islocal,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)xin));
    1361:       if (cando) {
    1362:         PetscMalloc2(1,&to12,1,&from12);
    1363:         to12->n            = nx;
    1364:         to12->first        = to_first;
    1365:         to12->step         = to_step;
    1366:         from12->n          = nx;
    1367:         from12->first      = from_first-start;
    1368:         from12->step       = from_step;
    1369:         to12->type         = VEC_SCATTER_SEQ_STRIDE;
    1370:         from12->type       = VEC_SCATTER_SEQ_STRIDE;
    1371:         ctx->todata        = (void*)to12;
    1372:         ctx->fromdata      = (void*)from12;
    1373:         ctx->ops->begin    = VecScatterBegin_SSToSS;
    1374:         ctx->ops->end      = 0;
    1375:         ctx->ops->destroy  = VecScatterDestroy_SSToSS;
    1376:         ctx->ops->copy     = VecScatterCopy_SSToSS;
    1377:         ctx->ops->view     = VecScatterView_SSToSS;
    1378:         PetscInfo(xin,"Special case: processors only getting local values\n");
    1379:         goto functionend;
    1380:       }
    1381:     } else {
    1382:       MPI_Allreduce(&islocal,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)xin));
    1383:     }

    1385:     /* test for special case of all processors getting entire vector */
    1386:     /* contains check that PetscMPIInt can handle the sizes needed */
    1387:     totalv = PETSC_FALSE;
    1388:     if (ix_type == IS_STRIDE_ID && iy_type == IS_STRIDE_ID) {
    1389:       PetscInt             i,nx,ny,to_first,to_step,from_first,from_step,N;
    1390:       PetscMPIInt          *count = NULL,*displx;
    1391:       VecScatter_MPI_ToAll *sto   = NULL;

    1393:       ISGetLocalSize(ix,&nx);
    1394:       ISStrideGetInfo(ix,&from_first,&from_step);
    1395:       ISGetLocalSize(iy,&ny);
    1396:       ISStrideGetInfo(iy,&to_first,&to_step);
    1397:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1398:       VecGetSize(xin,&N);
    1399:       if (nx != N) totalv = PETSC_FALSE;
    1400:       else if (from_first == 0 && from_step == 1 && from_first == to_first && from_step == to_step) totalv = PETSC_TRUE;
    1401:       else totalv = PETSC_FALSE;
    1402:       /* cannot use MPIU_Allreduce() since this call matches with the MPI_Allreduce() in the else statement below */
    1403:       MPI_Allreduce(&totalv,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)xin));

    1405: #if defined(PETSC_USE_64BIT_INDICES)
    1406:       if (cando && (yin->map->N < PETSC_MPI_INT_MAX)) {
    1407: #else
    1408:       if (cando) {
    1409: #endif
    1410:         MPI_Comm_size(PetscObjectComm((PetscObject)ctx),&size);
    1411:         PetscMalloc3(1,&sto,size,&count,size,&displx);
    1412:         range = xin->map->range;
    1413:         for (i=0; i<size; i++) {
    1414:           PetscMPIIntCast(range[i+1] - range[i],count+i);
    1415:           PetscMPIIntCast(range[i],displx+i);
    1416:         }
    1417:         sto->count        = count;
    1418:         sto->displx       = displx;
    1419:         sto->work1        = 0;
    1420:         sto->work2        = 0;
    1421:         sto->type         = VEC_SCATTER_MPI_TOALL;
    1422:         ctx->todata       = (void*)sto;
    1423:         ctx->fromdata     = 0;
    1424:         ctx->ops->begin   = VecScatterBegin_MPI_ToAll;
    1425:         ctx->ops->end     = 0;
    1426:         ctx->ops->destroy = VecScatterDestroy_MPI_ToAll;
    1427:         ctx->ops->copy    = VecScatterCopy_MPI_ToAll;
    1428:         ctx->ops->view    = VecScatterView_MPI_ToAll;
    1429:         PetscInfo(xin,"Special case: all processors get entire parallel vector\n");
    1430:         goto functionend;
    1431:       }
    1432:     } else {
    1433:       MPI_Allreduce(&totalv,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)xin));
    1434:     }

    1436:     /* test for special case of processor 0 getting entire vector */
    1437:     /* contains check that PetscMPIInt can handle the sizes needed */
    1438:     totalv = PETSC_FALSE;
    1439:     if (ix_type == IS_STRIDE_ID && iy_type == IS_STRIDE_ID) {
    1440:       PetscInt             i,nx,ny,to_first,to_step,from_first,from_step,N;
    1441:       PetscMPIInt          rank,*count = NULL,*displx;
    1442:       VecScatter_MPI_ToAll *sto = NULL;

    1444:       PetscObjectGetComm((PetscObject)xin,&comm);
    1445:       MPI_Comm_rank(comm,&rank);
    1446:       ISGetLocalSize(ix,&nx);
    1447:       ISStrideGetInfo(ix,&from_first,&from_step);
    1448:       ISGetLocalSize(iy,&ny);
    1449:       ISStrideGetInfo(iy,&to_first,&to_step);
    1450:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1451:       if (!rank) {
    1452:         VecGetSize(xin,&N);
    1453:         if (nx != N) totalv = PETSC_FALSE;
    1454:         else if (from_first == 0        && from_step == 1 &&
    1455:                  from_first == to_first && from_step == to_step) totalv = PETSC_TRUE;
    1456:         else totalv = PETSC_FALSE;
    1457:       } else {
    1458:         if (!nx) totalv = PETSC_TRUE;
    1459:         else     totalv = PETSC_FALSE;
    1460:       }
    1461:       /* cannot use MPIU_Allreduce() since this call matches with the MPI_Allreduce() in the else statement below */
    1462:       MPI_Allreduce(&totalv,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)xin));

    1464: #if defined(PETSC_USE_64BIT_INDICES)
    1465:       if (cando && (yin->map->N < PETSC_MPI_INT_MAX)) {
    1466: #else
    1467:       if (cando) {
    1468: #endif
    1469:         MPI_Comm_size(PetscObjectComm((PetscObject)ctx),&size);
    1470:         PetscMalloc3(1,&sto,size,&count,size,&displx);
    1471:         range = xin->map->range;
    1472:         for (i=0; i<size; i++) {
    1473:           PetscMPIIntCast(range[i+1] - range[i],count+i);
    1474:           PetscMPIIntCast(range[i],displx+i);
    1475:         }
    1476:         sto->count        = count;
    1477:         sto->displx       = displx;
    1478:         sto->work1        = 0;
    1479:         sto->work2        = 0;
    1480:         sto->type         = VEC_SCATTER_MPI_TOONE;
    1481:         ctx->todata       = (void*)sto;
    1482:         ctx->fromdata     = 0;
    1483:         ctx->ops->begin   = VecScatterBegin_MPI_ToOne;
    1484:         ctx->ops->end     = 0;
    1485:         ctx->ops->destroy = VecScatterDestroy_MPI_ToAll;
    1486:         ctx->ops->copy    = VecScatterCopy_MPI_ToAll;
    1487:         ctx->ops->view    = VecScatterView_MPI_ToAll;
    1488:         PetscInfo(xin,"Special case: processor zero gets entire parallel vector, rest get none\n");
    1489:         goto functionend;
    1490:       }
    1491:     } else {
    1492:       MPI_Allreduce(&totalv,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)xin));
    1493:     }

    1495:     PetscObjectTypeCompare((PetscObject)ix,ISBLOCK,&ixblock);
    1496:     PetscObjectTypeCompare((PetscObject)iy,ISBLOCK,&iyblock);
    1497:     PetscObjectTypeCompare((PetscObject)iy,ISSTRIDE,&iystride);
    1498:     if (ixblock) {
    1499:       /* special case block to block */
    1500:       if (iyblock) {
    1501:         PetscInt       nx,ny,bsx,bsy;
    1502:         const PetscInt *idx,*idy;
    1503:         ISGetBlockSize(iy,&bsy);
    1504:         ISGetBlockSize(ix,&bsx);
    1505:         if (bsx == bsy && VecScatterOptimizedBS(bsx)) {
    1506:           ISBlockGetLocalSize(ix,&nx);
    1507:           ISBlockGetIndices(ix,&idx);
    1508:           ISBlockGetLocalSize(iy,&ny);
    1509:           ISBlockGetIndices(iy,&idy);
    1510:           if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1511:           VecScatterCreate_PtoS(nx,idx,ny,idy,xin,yin,bsx,ctx);
    1512:           ISBlockRestoreIndices(ix,&idx);
    1513:           ISBlockRestoreIndices(iy,&idy);
    1514:           PetscInfo(xin,"Special case: blocked indices\n");
    1515:           goto functionend;
    1516:         }
    1517:         /* special case block to stride */
    1518:       } else if (iystride) {
    1519:         PetscInt ystart,ystride,ysize,bsx;
    1520:         ISStrideGetInfo(iy,&ystart,&ystride);
    1521:         ISGetLocalSize(iy,&ysize);
    1522:         ISGetBlockSize(ix,&bsx);
    1523:         /* see if stride index set is equivalent to block index set */
    1524:         if (VecScatterOptimizedBS(bsx) && ((ystart % bsx) == 0) && (ystride == 1) && ((ysize % bsx) == 0)) {
    1525:           PetscInt       nx,il,*idy;
    1526:           const PetscInt *idx;
    1527:           ISBlockGetLocalSize(ix,&nx);
    1528:           ISBlockGetIndices(ix,&idx);
    1529:           if (ysize != bsx*nx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1530:           PetscMalloc1(nx,&idy);
    1531:           if (nx) {
    1532:             idy[0] = ystart/bsx;
    1533:             for (il=1; il<nx; il++) idy[il] = idy[il-1] + 1;
    1534:           }
    1535:           VecScatterCreate_PtoS(nx,idx,nx,idy,xin,yin,bsx,ctx);
    1536:           PetscFree(idy);
    1537:           ISBlockRestoreIndices(ix,&idx);
    1538:           PetscInfo(xin,"Special case: blocked indices to stride\n");
    1539:           goto functionend;
    1540:         }
    1541:       }
    1542:     }
    1543:     /* left over general case */
    1544:     {
    1545:       PetscInt       nx,ny;
    1546:       const PetscInt *idx,*idy;
    1547:       ISGetLocalSize(ix,&nx);
    1548:       ISGetIndices(ix,&idx);
    1549:       ISGetLocalSize(iy,&ny);
    1550:       ISGetIndices(iy,&idy);
    1551:       if (nx != ny) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match (%d %d)",nx,ny);
    1552:       VecScatterCreate_PtoS(nx,idx,ny,idy,xin,yin,1,ctx);
    1553:       ISRestoreIndices(ix,&idx);
    1554:       ISRestoreIndices(iy,&idy);
    1555:       PetscInfo(xin,"General case: MPI to Seq\n");
    1556:       goto functionend;
    1557:     }
    1558:   }
    1559:   /* ---------------------------------------------------------------------------*/
    1560:   if (xin_type == VEC_SEQ_ID && yin_type == VEC_MPI_ID) {
    1561:     /* ===========================================================================================================
    1562:           Check for special cases
    1563:        ==========================================================================================================*/
    1564:     /* special case local copy portion */
    1565:     islocal = PETSC_FALSE;
    1566:     if (ix_type == IS_STRIDE_ID && iy_type == IS_STRIDE_ID) {
    1567:       PetscInt              nx,ny,to_first,to_step,from_step,start,end,from_first,min,max;
    1568:       VecScatter_Seq_Stride *from = NULL,*to = NULL;

    1570:       VecGetOwnershipRange(yin,&start,&end);
    1571:       ISGetLocalSize(ix,&nx);
    1572:       ISStrideGetInfo(ix,&from_first,&from_step);
    1573:       ISGetLocalSize(iy,&ny);
    1574:       ISStrideGetInfo(iy,&to_first,&to_step);
    1575:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1576:       ISGetMinMax(iy,&min,&max);
    1577:       if (min >= start && max < end) islocal = PETSC_TRUE;
    1578:       else islocal = PETSC_FALSE;
    1579:       /* cannot use MPIU_Allreduce() since this call matches with the MPI_Allreduce() in the else statement below */
    1580:       MPI_Allreduce(&islocal,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)yin));
    1581:       if (cando) {
    1582:         PetscMalloc2(1,&to,1,&from);
    1583:         to->n             = nx;
    1584:         to->first         = to_first-start;
    1585:         to->step          = to_step;
    1586:         from->n           = nx;
    1587:         from->first       = from_first;
    1588:         from->step        = from_step;
    1589:         to->type          = VEC_SCATTER_SEQ_STRIDE;
    1590:         from->type        = VEC_SCATTER_SEQ_STRIDE;
    1591:         ctx->todata       = (void*)to;
    1592:         ctx->fromdata     = (void*)from;
    1593:         ctx->ops->begin   = VecScatterBegin_SSToSS;
    1594:         ctx->ops->end     = 0;
    1595:         ctx->ops->destroy = VecScatterDestroy_SSToSS;
    1596:         ctx->ops->copy    = VecScatterCopy_SSToSS;
    1597:         ctx->ops->view    = VecScatterView_SSToSS;
    1598:         PetscInfo(xin,"Special case: sequential stride to MPI stride\n");
    1599:         goto functionend;
    1600:       }
    1601:     } else {
    1602:       MPI_Allreduce(&islocal,&cando,1,MPIU_BOOL,MPI_LAND,PetscObjectComm((PetscObject)yin));
    1603:     }
    1604:     /* special case block to stride */
    1605:     if (ix_type == IS_BLOCK_ID && iy_type == IS_STRIDE_ID) {
    1606:       PetscInt ystart,ystride,ysize,bsx;
    1607:       ISStrideGetInfo(iy,&ystart,&ystride);
    1608:       ISGetLocalSize(iy,&ysize);
    1609:       ISGetBlockSize(ix,&bsx);
    1610:       /* see if stride index set is equivalent to block index set */
    1611:       if (VecScatterOptimizedBS(bsx) && ((ystart % bsx) == 0) && (ystride == 1) && ((ysize % bsx) == 0)) {
    1612:         PetscInt       nx,il,*idy;
    1613:         const PetscInt *idx;
    1614:         ISBlockGetLocalSize(ix,&nx);
    1615:         ISBlockGetIndices(ix,&idx);
    1616:         if (ysize != bsx*nx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1617:         PetscMalloc1(nx,&idy);
    1618:         if (nx) {
    1619:           idy[0] = ystart/bsx;
    1620:           for (il=1; il<nx; il++) idy[il] = idy[il-1] + 1;
    1621:         }
    1622:         VecScatterCreate_StoP(nx,idx,nx,idy,xin,yin,bsx,ctx);
    1623:         PetscFree(idy);
    1624:         ISBlockRestoreIndices(ix,&idx);
    1625:         PetscInfo(xin,"Special case: Blocked indices to stride\n");
    1626:         goto functionend;
    1627:       }
    1628:     }

    1630:     /* general case */
    1631:     {
    1632:       PetscInt       nx,ny;
    1633:       const PetscInt *idx,*idy;
    1634:       ISGetLocalSize(ix,&nx);
    1635:       ISGetIndices(ix,&idx);
    1636:       ISGetLocalSize(iy,&ny);
    1637:       ISGetIndices(iy,&idy);
    1638:       if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1639:       VecScatterCreate_StoP(nx,idx,ny,idy,xin,yin,1,ctx);
    1640:       ISRestoreIndices(ix,&idx);
    1641:       ISRestoreIndices(iy,&idy);
    1642:       PetscInfo(xin,"General case: Seq to MPI\n");
    1643:       goto functionend;
    1644:     }
    1645:   }
    1646:   /* ---------------------------------------------------------------------------*/
    1647:   if (xin_type == VEC_MPI_ID && yin_type == VEC_MPI_ID) {
    1648:     /* no special cases for now */
    1649:     PetscInt       nx,ny;
    1650:     const PetscInt *idx,*idy;
    1651:     ISGetLocalSize(ix,&nx);
    1652:     ISGetIndices(ix,&idx);
    1653:     ISGetLocalSize(iy,&ny);
    1654:     ISGetIndices(iy,&idy);
    1655:     if (nx != ny) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Local scatter sizes don't match");
    1656:     VecScatterCreate_PtoP(nx,idx,ny,idy,xin,yin,1,ctx);
    1657:     ISRestoreIndices(ix,&idx);
    1658:     ISRestoreIndices(iy,&idy);
    1659:     PetscInfo(xin,"General case: MPI to MPI\n");
    1660:     goto functionend;
    1661:   }

    1663:   functionend:
    1664:   *newctx = ctx;
    1665:   ISDestroy(&tix);
    1666:   ISDestroy(&tiy);
    1667:   VecScatterViewFromOptions(ctx,NULL,"-vecscatter_view");
    1668:   return(0);
    1669: }

    1671: /* ------------------------------------------------------------------*/
    1674: /*@
    1675:    VecScatterGetMerged - Returns true if the scatter is completed in the VecScatterBegin()
    1676:       and the VecScatterEnd() does nothing

    1678:    Not Collective

    1680:    Input Parameter:
    1681: .   ctx - scatter context created with VecScatterCreate()

    1683:    Output Parameter:
    1684: .   flg - PETSC_TRUE if the VecScatterBegin/End() are all done during the VecScatterBegin()

    1686:    Level: developer

    1688: .seealso: VecScatterCreate(), VecScatterEnd(), VecScatterBegin()
    1689: @*/
    1690: PetscErrorCode  VecScatterGetMerged(VecScatter ctx,PetscBool  *flg)
    1691: {
    1694:   *flg = ctx->beginandendtogether;
    1695:   return(0);
    1696: }

    1700: /*@
    1701:    VecScatterBegin - Begins a generalized scatter from one vector to
    1702:    another. Complete the scattering phase with VecScatterEnd().

    1704:    Neighbor-wise Collective on VecScatter and Vec

    1706:    Input Parameters:
    1707: +  inctx - scatter context generated by VecScatterCreate()
    1708: .  x - the vector from which we scatter
    1709: .  y - the vector to which we scatter
    1710: .  addv - either ADD_VALUES or INSERT_VALUES, with INSERT_VALUES mode any location
    1711:           not scattered to retains its old value; i.e. the vector is NOT first zeroed.
    1712: -  mode - the scattering mode, usually SCATTER_FORWARD.  The available modes are:
    1713:     SCATTER_FORWARD or SCATTER_REVERSE

    1716:    Level: intermediate

    1718:    Options Database: See VecScatterCreate()

    1720:    Notes:
    1721:    The vectors x and y need not be the same vectors used in the call
    1722:    to VecScatterCreate(), but x must have the same parallel data layout
    1723:    as that passed in as the x to VecScatterCreate(), similarly for the y.
    1724:    Most likely they have been obtained from VecDuplicate().

    1726:    You cannot change the values in the input vector between the calls to VecScatterBegin()
    1727:    and VecScatterEnd().

    1729:    If you use SCATTER_REVERSE the two arguments x and y should be reversed, from
    1730:    the SCATTER_FORWARD.

    1732:    y[iy[i]] = x[ix[i]], for i=0,...,ni-1

    1734:    This scatter is far more general than the conventional
    1735:    scatter, since it can be a gather or a scatter or a combination,
    1736:    depending on the indices ix and iy.  If x is a parallel vector and y
    1737:    is sequential, VecScatterBegin() can serve to gather values to a
    1738:    single processor.  Similarly, if y is parallel and x sequential, the
    1739:    routine can scatter from one processor to many processors.

    1741:    Concepts: scatter^between vectors
    1742:    Concepts: gather^between vectors

    1744: .seealso: VecScatterCreate(), VecScatterEnd()
    1745: @*/
    1746: PetscErrorCode  VecScatterBegin(VecScatter inctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    1747: {
    1749: #if defined(PETSC_USE_DEBUG)
    1750:   PetscInt       to_n,from_n;
    1751: #endif
    1756:   if (inctx->inuse) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE," Scatter ctx already in use");

    1758: #if defined(PETSC_USE_DEBUG)
    1759:   /*
    1760:      Error checking to make sure these vectors match the vectors used
    1761:    to create the vector scatter context. -1 in the from_n and to_n indicate the
    1762:    vector lengths are unknown (for example with mapped scatters) and thus
    1763:    no error checking is performed.
    1764:   */
    1765:   if (inctx->from_n >= 0 && inctx->to_n >= 0) {
    1766:     VecGetLocalSize(x,&from_n);
    1767:     VecGetLocalSize(y,&to_n);
    1768:     if (mode & SCATTER_REVERSE) {
    1769:       if (to_n != inctx->from_n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Vector wrong size %D for scatter %D (scatter reverse and vector to != ctx from size)",to_n,inctx->from_n);
    1770:       if (from_n != inctx->to_n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Vector wrong size %D for scatter %D (scatter reverse and vector from != ctx to size)",from_n,inctx->to_n);
    1771:     } else {
    1772:       if (to_n != inctx->to_n)     SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Vector wrong size %D for scatter %D (scatter forward and vector to != ctx to size)",to_n,inctx->to_n);
    1773:       if (from_n != inctx->from_n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Vector wrong size %D for scatter %D (scatter forward and vector from != ctx from size)",from_n,inctx->from_n);
    1774:     }
    1775:   }
    1776: #endif

    1778:   inctx->inuse = PETSC_TRUE;
    1779:   PetscLogEventBarrierBegin(VEC_ScatterBarrier,0,0,0,0,PetscObjectComm((PetscObject)inctx));
    1780:   (*inctx->ops->begin)(inctx,x,y,addv,mode);
    1781:   if (inctx->beginandendtogether && inctx->ops->end) {
    1782:     inctx->inuse = PETSC_FALSE;
    1783:     (*inctx->ops->end)(inctx,x,y,addv,mode);
    1784:   }
    1785:   PetscLogEventBarrierEnd(VEC_ScatterBarrier,0,0,0,0,PetscObjectComm((PetscObject)inctx));
    1786:   return(0);
    1787: }

    1789: /* --------------------------------------------------------------------*/
    1792: /*@
    1793:    VecScatterEnd - Ends a generalized scatter from one vector to another.  Call
    1794:    after first calling VecScatterBegin().

    1796:    Neighbor-wise Collective on VecScatter and Vec

    1798:    Input Parameters:
    1799: +  ctx - scatter context generated by VecScatterCreate()
    1800: .  x - the vector from which we scatter
    1801: .  y - the vector to which we scatter
    1802: .  addv - either ADD_VALUES or INSERT_VALUES.
    1803: -  mode - the scattering mode, usually SCATTER_FORWARD.  The available modes are:
    1804:      SCATTER_FORWARD, SCATTER_REVERSE

    1806:    Level: intermediate

    1808:    Notes:
    1809:    If you use SCATTER_REVERSE the arguments x and y should be reversed, from the SCATTER_FORWARD.

    1811:    y[iy[i]] = x[ix[i]], for i=0,...,ni-1

    1813: .seealso: VecScatterBegin(), VecScatterCreate()
    1814: @*/
    1815: PetscErrorCode  VecScatterEnd(VecScatter ctx,Vec x,Vec y,InsertMode addv,ScatterMode mode)
    1816: {

    1823:   ctx->inuse = PETSC_FALSE;
    1824:   if (!ctx->ops->end) return(0);
    1825:   if (!ctx->beginandendtogether) {
    1826:     PetscLogEventBegin(VEC_ScatterEnd,ctx,x,y,0);
    1827:     (*(ctx)->ops->end)(ctx,x,y,addv,mode);
    1828:     PetscLogEventEnd(VEC_ScatterEnd,ctx,x,y,0);
    1829:   }
    1830:   return(0);
    1831: }

    1835: /*@C
    1836:    VecScatterDestroy - Destroys a scatter context created by
    1837:    VecScatterCreate().

    1839:    Collective on VecScatter

    1841:    Input Parameter:
    1842: .  ctx - the scatter context

    1844:    Level: intermediate

    1846: .seealso: VecScatterCreate(), VecScatterCopy()
    1847: @*/
    1848: PetscErrorCode  VecScatterDestroy(VecScatter *ctx)
    1849: {

    1853:   if (!*ctx) return(0);
    1855:   if ((*ctx)->inuse) SETERRQ(((PetscObject)(*ctx))->comm,PETSC_ERR_ARG_WRONGSTATE,"Scatter context is in use");
    1856:   if (--((PetscObject)(*ctx))->refct > 0) {*ctx = 0; return(0);}

    1858:   /* if memory was published with SAWs then destroy it */
    1859:   PetscObjectSAWsViewOff((PetscObject)(*ctx));
    1860:   (*(*ctx)->ops->destroy)(*ctx);
    1861: #if defined(PETSC_HAVE_CUSP)
    1862:   VecScatterCUSPIndicesDestroy((PetscCUSPIndices*)&((*ctx)->spptr));
    1863: #elif defined(PETSC_HAVE_VECCUDA)
    1864:   VecScatterCUDAIndicesDestroy((PetscCUDAIndices*)&((*ctx)->spptr));
    1865: #endif
    1866:   PetscHeaderDestroy(ctx);
    1867:   return(0);
    1868: }

    1872: /*@
    1873:    VecScatterCopy - Makes a copy of a scatter context.

    1875:    Collective on VecScatter

    1877:    Input Parameter:
    1878: .  sctx - the scatter context

    1880:    Output Parameter:
    1881: .  ctx - the context copy

    1883:    Level: advanced

    1885: .seealso: VecScatterCreate(), VecScatterDestroy()
    1886: @*/
    1887: PetscErrorCode  VecScatterCopy(VecScatter sctx,VecScatter *ctx)
    1888: {

    1894:   if (!sctx->ops->copy) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Cannot copy this type");
    1895:   PetscHeaderCreate(*ctx,VEC_SCATTER_CLASSID,"VecScatter","VecScatter","Vec",PetscObjectComm((PetscObject)sctx),VecScatterDestroy,VecScatterView);
    1896:   (*ctx)->to_n   = sctx->to_n;
    1897:   (*ctx)->from_n = sctx->from_n;
    1898:   (*sctx->ops->copy)(sctx,*ctx);
    1899:   return(0);
    1900: }

    1903: /* ------------------------------------------------------------------*/
    1906: /*@
    1907:    VecScatterView - Views a vector scatter context.

    1909:    Collective on VecScatter

    1911:    Input Parameters:
    1912: +  ctx - the scatter context
    1913: -  viewer - the viewer for displaying the context

    1915:    Level: intermediate

    1917: @*/
    1918: PetscErrorCode  VecScatterView(VecScatter ctx,PetscViewer viewer)
    1919: {

    1924:   if (!viewer) {
    1925:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)ctx),&viewer);
    1926:   }
    1928:   if (ctx->ops->view) {
    1929:     (*ctx->ops->view)(ctx,viewer);
    1930:   }
    1931:   return(0);
    1932: }

    1936: /*@C
    1937:    VecScatterRemap - Remaps the "from" and "to" indices in a
    1938:    vector scatter context. FOR EXPERTS ONLY!

    1940:    Collective on VecScatter

    1942:    Input Parameters:
    1943: +  scat - vector scatter context
    1944: .  from - remapping for "from" indices (may be NULL)
    1945: -  to   - remapping for "to" indices (may be NULL)

    1947:    Level: developer

    1949:    Notes: In the parallel case the todata is actually the indices
    1950:           from which the data is TAKEN! The from stuff is where the
    1951:           data is finally put. This is VERY VERY confusing!

    1953:           In the sequential case the todata is the indices where the
    1954:           data is put and the fromdata is where it is taken from.
    1955:           This is backwards from the paralllel case! CRY! CRY! CRY!

    1957: @*/
    1958: PetscErrorCode  VecScatterRemap(VecScatter scat,PetscInt *rto,PetscInt *rfrom)
    1959: {
    1960:   VecScatter_Seq_General *to,*from;
    1961:   VecScatter_MPI_General *mto;
    1962:   PetscInt               i;

    1969:   from = (VecScatter_Seq_General*)scat->fromdata;
    1970:   mto  = (VecScatter_MPI_General*)scat->todata;

    1972:   if (mto->type == VEC_SCATTER_MPI_TOALL) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Not for to all scatter");

    1974:   if (rto) {
    1975:     if (mto->type == VEC_SCATTER_MPI_GENERAL) {
    1976:       /* handle off processor parts */
    1977:       for (i=0; i<mto->starts[mto->n]; i++) mto->indices[i] = rto[mto->indices[i]];

    1979:       /* handle local part */
    1980:       to = &mto->local;
    1981:       for (i=0; i<to->n; i++) to->vslots[i] = rto[to->vslots[i]];
    1982:     } else if (from->type == VEC_SCATTER_SEQ_GENERAL) {
    1983:       for (i=0; i<from->n; i++) from->vslots[i] = rto[from->vslots[i]];
    1984:     } else if (from->type == VEC_SCATTER_SEQ_STRIDE) {
    1985:       VecScatter_Seq_Stride *sto = (VecScatter_Seq_Stride*)from;

    1987:       /* if the remapping is the identity and stride is identity then skip remap */
    1988:       if (sto->step == 1 && sto->first == 0) {
    1989:         for (i=0; i<sto->n; i++) {
    1990:           if (rto[i] != i) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Unable to remap such scatters");
    1991:         }
    1992:       } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Unable to remap such scatters");
    1993:     } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Unable to remap such scatters");
    1994:   }

    1996:   if (rfrom) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Unable to remap the FROM in scatters yet");

    1998:   /*
    1999:      Mark then vector lengths as unknown because we do not know the
    2000:    lengths of the remapped vectors
    2001:   */
    2002:   scat->from_n = -1;
    2003:   scat->to_n   = -1;
    2004:   return(0);
    2005: }

    2009: /*
    2010:  VecScatterGetTypes_Private - Returns the scatter types.

    2012:  scatter - The scatter.
    2013:  from    - Upon exit this contains the type of the from scatter.
    2014:  to      - Upon exit this contains the type of the to scatter.
    2015: */
    2016: PetscErrorCode VecScatterGetTypes_Private(VecScatter scatter,VecScatterType *from,VecScatterType *to)
    2017: {
    2018:   VecScatter_Common* fromdata = (VecScatter_Common*)scatter->fromdata;
    2019:   VecScatter_Common* todata   = (VecScatter_Common*)scatter->todata;

    2022:   *from = fromdata->type;
    2023:   *to = todata->type;
    2024:   return(0);
    2025: }

    2030: /*
    2031:   VecScatterIsSequential_Private - Returns true if the scatter is sequential.

    2033:   scatter - The scatter.
    2034:   flag    - Upon exit flag is true if the scatter is of type VecScatter_Seq_General
    2035:             or VecScatter_Seq_Stride; otherwise flag is false.
    2036: */
    2037: PetscErrorCode VecScatterIsSequential_Private(VecScatter_Common *scatter,PetscBool *flag)
    2038: {
    2039:   VecScatterType scatterType = scatter->type;

    2042:   if (scatterType == VEC_SCATTER_SEQ_GENERAL || scatterType == VEC_SCATTER_SEQ_STRIDE) {
    2043:     *flag = PETSC_TRUE;
    2044:   } else {
    2045:     *flag = PETSC_FALSE;
    2046:   }
    2047:   return(0);
    2048: }

    2050: #if defined(PETSC_HAVE_CUSP) || defined(PETSC_HAVE_VECCUDA)

    2054: /*@C
    2055:    VecScatterInitializeForGPU - Initializes a generalized scatter from one vector
    2056:    to another for GPU based computation.

    2058:    Input Parameters:
    2059: +  inctx - scatter context generated by VecScatterCreate()
    2060: .  x - the vector from which we scatter
    2061: -  mode - the scattering mode, usually SCATTER_FORWARD.  The available modes are:
    2062:     SCATTER_FORWARD or SCATTER_REVERSE

    2064:   Level: intermediate

    2066:   Notes:
    2067:    Effectively, this function creates all the necessary indexing buffers and work
    2068:    vectors needed to move data only those data points in a vector which need to
    2069:    be communicated across ranks. This is done at the first time this function is
    2070:    called. Currently, this only used in the context of the parallel SpMV call in
    2071:    MatMult_MPIAIJCUSP or MatMult_MPIAIJCUSPARSE.

    2073:    This function is executed before the call to MatMult. This enables the memory
    2074:    transfers to be overlapped with the MatMult SpMV kernel call.

    2076: .seealso: VecScatterFinalizeForGPU(), VecScatterCreate(), VecScatterEnd()
    2077: @*/
    2078: PETSC_EXTERN PetscErrorCode VecScatterInitializeForGPU(VecScatter inctx,Vec x,ScatterMode mode)
    2079: {
    2081:   VecScatter_MPI_General *to,*from;
    2082:   PetscErrorCode         ierr;
    2083:   PetscInt               i,*indices,*sstartsSends,*sstartsRecvs,nrecvs,nsends,bs;
    2084:   PetscBool              isSeq1,isSeq2;

    2087:   VecScatterIsSequential_Private((VecScatter_Common*)inctx->fromdata,&isSeq1);
    2088:   VecScatterIsSequential_Private((VecScatter_Common*)inctx->todata,&isSeq2);
    2089:   if (isSeq1 || isSeq2) {
    2090:     return(0);
    2091:   }
    2092:   if (mode & SCATTER_REVERSE) {
    2093:     to     = (VecScatter_MPI_General*)inctx->fromdata;
    2094:     from   = (VecScatter_MPI_General*)inctx->todata;
    2095:   } else {
    2096:     to     = (VecScatter_MPI_General*)inctx->todata;
    2097:     from   = (VecScatter_MPI_General*)inctx->fromdata;
    2098:   }
    2099:   bs           = to->bs;
    2100:   nrecvs       = from->n;
    2101:   nsends       = to->n;
    2102:   indices      = to->indices;
    2103:   sstartsSends = to->starts;
    2104:   sstartsRecvs = from->starts;
    2105: #if defined(PETSC_HAVE_CUSP)
    2106:   if (x->valid_GPU_array != PETSC_CUSP_UNALLOCATED && (nsends>0 || nrecvs>0)) {
    2107: #else
    2108:   if (x->valid_GPU_array != PETSC_CUDA_UNALLOCATED && (nsends>0 || nrecvs>0)) {
    2109: #endif
    2110:     if (!inctx->spptr) {
    2111:       PetscInt k,*tindicesSends,*sindicesSends,*tindicesRecvs,*sindicesRecvs;
    2112:       PetscInt ns = sstartsSends[nsends],nr = sstartsRecvs[nrecvs];
    2113:       /* Here we create indices for both the senders and receivers. */
    2114:       PetscMalloc1(ns,&tindicesSends);
    2115:       PetscMalloc1(nr,&tindicesRecvs);

    2117:       PetscMemcpy(tindicesSends,indices,ns*sizeof(PetscInt));
    2118:       PetscMemcpy(tindicesRecvs,from->indices,nr*sizeof(PetscInt));

    2120:       PetscSortRemoveDupsInt(&ns,tindicesSends);
    2121:       PetscSortRemoveDupsInt(&nr,tindicesRecvs);

    2123:       PetscMalloc1(bs*ns,&sindicesSends);
    2124:       PetscMalloc1(from->bs*nr,&sindicesRecvs);

    2126:       /* sender indices */
    2127:       for (i=0; i<ns; i++) {
    2128:         for (k=0; k<bs; k++) sindicesSends[i*bs+k] = tindicesSends[i]+k;
    2129:       }
    2130:       PetscFree(tindicesSends);

    2132:       /* receiver indices */
    2133:       for (i=0; i<nr; i++) {
    2134:         for (k=0; k<from->bs; k++) sindicesRecvs[i*from->bs+k] = tindicesRecvs[i]+k;
    2135:       }
    2136:       PetscFree(tindicesRecvs);

    2138:       /* create GPU indices, work vectors, ... */
    2139: #if defined(PETSC_HAVE_CUSP)
    2140:       VecScatterCUSPIndicesCreate_PtoP(ns*bs,sindicesSends,nr*from->bs,sindicesRecvs,(PetscCUSPIndices*)&inctx->spptr);
    2141: #else
    2142:       VecScatterCUDAIndicesCreate_PtoP(ns*bs,sindicesSends,nr*from->bs,sindicesRecvs,(PetscCUDAIndices*)&inctx->spptr);
    2143: #endif
    2144:       PetscFree(sindicesSends);
    2145:       PetscFree(sindicesRecvs);
    2146:     }
    2147:   }
    2148:   return(0);
    2149: }

    2153: /*@C
    2154:    VecScatterFinalizeForGPU - Finalizes a generalized scatter from one vector to
    2155:    another for GPU based computation.

    2157:    Input Parameter:
    2158: +  inctx - scatter context generated by VecScatterCreate()

    2160:   Level: intermediate

    2162:   Notes:
    2163:    Effectively, this function resets the temporary buffer flags. Currently, this
    2164:    only used in the context of the parallel SpMV call in in MatMult_MPIAIJCUDA
    2165:    or MatMult_MPIAIJCUDAARSE. Once the MatMultAdd is finished, the GPU temporary
    2166:    buffers used for messaging are no longer valid.

    2168: .seealso: VecScatterInitializeForGPU(), VecScatterCreate(), VecScatterEnd()
    2169: @*/
    2170: PETSC_EXTERN PetscErrorCode VecScatterFinalizeForGPU(VecScatter inctx)
    2171: {
    2173:   return(0);
    2174: }

    2176: #endif