Actual source code: pbvec.c

  1: /*
  2:    This file contains routines for Parallel vector operations.
  3:  */
  4: #include <petscsys.h>
  5: #include <../src/vec/vec/impls/mpi/pvecimpl.h>

  7: PETSC_INTERN PetscErrorCode VecView_MPI_Draw(Vec, PetscViewer);

  9: PetscErrorCode VecPlaceArray_MPI(Vec vin, const PetscScalar *a)
 10: {
 11:   Vec_MPI *v = (Vec_MPI *)vin->data;

 13:   PetscFunctionBegin;
 14:   PetscCheck(!v->unplacedarray, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "VecPlaceArray() was already called on this vector, without a call to VecResetArray()");
 15:   v->unplacedarray = v->array; /* save previous array so reset can bring it back */
 16:   v->array         = (PetscScalar *)a;
 17:   if (v->localrep) PetscCall(VecPlaceArray(v->localrep, a));
 18:   PetscFunctionReturn(PETSC_SUCCESS);
 19: }

 21: PetscErrorCode VecDuplicate_MPI(Vec win, Vec *v)
 22: {
 23:   Vec_MPI     *vw, *w = (Vec_MPI *)win->data;
 24:   PetscScalar *array;

 26:   PetscFunctionBegin;
 27:   PetscCall(VecCreateWithLayout_Private(win->map, v));

 29:   PetscCall(VecCreate_MPI_Private(*v, PETSC_TRUE, w->nghost, NULL));
 30:   vw           = (Vec_MPI *)(*v)->data;
 31:   (*v)->ops[0] = win->ops[0];

 33:   /* save local representation of the parallel vector (and scatter) if it exists */
 34:   if (w->localrep) {
 35:     PetscCall(VecGetArray(*v, &array));
 36:     PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, PetscAbs(win->map->bs), win->map->n + w->nghost, array, &vw->localrep));
 37:     vw->localrep->ops[0] = w->localrep->ops[0];
 38:     PetscCall(VecRestoreArray(*v, &array));

 40:     vw->localupdate = w->localupdate;
 41:     if (vw->localupdate) PetscCall(PetscObjectReference((PetscObject)vw->localupdate));

 43:     vw->ghost = w->ghost;
 44:     if (vw->ghost) PetscCall(PetscObjectReference((PetscObject)vw->ghost));
 45:   }

 47:   /* New vector should inherit stashing property of parent */
 48:   (*v)->stash.donotstash   = win->stash.donotstash;
 49:   (*v)->stash.ignorenegidx = win->stash.ignorenegidx;

 51:   PetscCall(PetscObjectListDuplicate(((PetscObject)win)->olist, &((PetscObject)*v)->olist));
 52:   PetscCall(PetscFunctionListDuplicate(((PetscObject)win)->qlist, &((PetscObject)*v)->qlist));

 54:   (*v)->bstash.bs = win->bstash.bs;
 55:   PetscFunctionReturn(PETSC_SUCCESS);
 56: }

 58: static PetscErrorCode VecDuplicateVecs_MPI_GEMV(Vec w, PetscInt m, Vec *V[])
 59: {
 60:   Vec_MPI *wmpi = (Vec_MPI *)w->data;

 62:   PetscFunctionBegin;
 63:   // Currently only do GEMV for vectors without ghosts. Note w might be a VECMPI subclass object.
 64:   // This routine relies on the duplicate operation being VecDuplicate_MPI. If not, bail out to the default.
 65:   if (wmpi->localrep || w->ops->duplicate != VecDuplicate_MPI) {
 66:     w->ops->duplicatevecs = VecDuplicateVecs_Default;
 67:     PetscCall(VecDuplicateVecs(w, m, V));
 68:   } else {
 69:     PetscScalar *array;
 70:     PetscInt64   lda; // use 64-bit as we will do "m * lda"

 72:     PetscCall(PetscMalloc1(m, V));
 73:     VecGetLocalSizeAligned(w, 64, &lda); // get in lda the 64-bytes aligned local size

 75:     PetscCall(PetscCalloc1(m * lda, &array));
 76:     for (PetscInt i = 0; i < m; i++) {
 77:       Vec v;
 78:       PetscCall(VecCreateMPIWithLayoutAndArray_Private(w->map, PetscSafePointerPlusOffset(array, i * lda), &v));
 79:       PetscCall(PetscObjectListDuplicate(((PetscObject)w)->olist, &((PetscObject)v)->olist));
 80:       PetscCall(PetscFunctionListDuplicate(((PetscObject)w)->qlist, &((PetscObject)v)->qlist));
 81:       v->ops->view          = w->ops->view;
 82:       v->stash.donotstash   = w->stash.donotstash;
 83:       v->stash.ignorenegidx = w->stash.ignorenegidx;
 84:       v->stash.bs           = w->stash.bs;
 85:       (*V)[i]               = v;
 86:     }
 87:     // So when the first vector is destroyed it will destroy the array
 88:     if (m) ((Vec_MPI *)(*V)[0]->data)->array_allocated = array;
 89:     // disable replacearray of the first vector, as freeing its memory also frees others in the group.
 90:     // But replacearray of others is ok, as they don't own their array.
 91:     if (m > 1) (*V)[0]->ops->replacearray = VecReplaceArray_Default_GEMV_Error;
 92:   }
 93:   PetscFunctionReturn(PETSC_SUCCESS);
 94: }

 96: static PetscErrorCode VecSetOption_MPI(Vec V, VecOption op, PetscBool flag)
 97: {
 98:   Vec_MPI *v = (Vec_MPI *)V->data;

100:   PetscFunctionBegin;
101:   switch (op) {
102:   case VEC_IGNORE_OFF_PROC_ENTRIES:
103:     V->stash.donotstash = flag;
104:     break;
105:   case VEC_IGNORE_NEGATIVE_INDICES:
106:     V->stash.ignorenegidx = flag;
107:     break;
108:   case VEC_SUBSET_OFF_PROC_ENTRIES:
109:     v->assembly_subset = flag;              /* See the same logic in MatAssembly wrt MAT_SUBSET_OFF_PROC_ENTRIES */
110:     if (!v->assembly_subset) {              /* User indicates "do not reuse the communication pattern" */
111:       PetscCall(VecAssemblyReset_MPI(V));   /* Reset existing pattern to free memory */
112:       v->first_assembly_done = PETSC_FALSE; /* Mark the first assembly is not done */
113:     }
114:     break;
115:   }
116:   PetscFunctionReturn(PETSC_SUCCESS);
117: }

119: PetscErrorCode VecResetArray_MPI(Vec vin)
120: {
121:   Vec_MPI *v = (Vec_MPI *)vin->data;

123:   PetscFunctionBegin;
124:   v->array         = v->unplacedarray;
125:   v->unplacedarray = NULL;
126:   if (v->localrep) PetscCall(VecResetArray(v->localrep));
127:   PetscFunctionReturn(PETSC_SUCCESS);
128: }

130: static PetscErrorCode VecAssemblySend_MPI_Private(MPI_Comm comm, const PetscMPIInt tag[], PetscMPIInt rankid, PetscMPIInt rank, void *sdata, MPI_Request req[], void *ctx)
131: {
132:   Vec                X   = (Vec)ctx;
133:   Vec_MPI           *x   = (Vec_MPI *)X->data;
134:   VecAssemblyHeader *hdr = (VecAssemblyHeader *)sdata;
135:   PetscInt           bs  = X->map->bs;

137:   PetscFunctionBegin;
138:   /* x->first_assembly_done indicates we are reusing a communication network. In that case, some
139:      messages can be empty, but we have to send them this time if we sent them before because the
140:      receiver is expecting them.
141:    */
142:   if (hdr->count || (x->first_assembly_done && x->sendptrs[rankid].ints)) {
143:     PetscCallMPI(MPI_Isend(x->sendptrs[rankid].ints, hdr->count, MPIU_INT, rank, tag[0], comm, &req[0]));
144:     PetscCallMPI(MPI_Isend(x->sendptrs[rankid].scalars, hdr->count, MPIU_SCALAR, rank, tag[1], comm, &req[1]));
145:   }
146:   if (hdr->bcount || (x->first_assembly_done && x->sendptrs[rankid].intb)) {
147:     PetscCallMPI(MPI_Isend(x->sendptrs[rankid].intb, hdr->bcount, MPIU_INT, rank, tag[2], comm, &req[2]));
148:     PetscCallMPI(MPI_Isend(x->sendptrs[rankid].scalarb, hdr->bcount * bs, MPIU_SCALAR, rank, tag[3], comm, &req[3]));
149:   }
150:   PetscFunctionReturn(PETSC_SUCCESS);
151: }

153: static PetscErrorCode VecAssemblyRecv_MPI_Private(MPI_Comm comm, const PetscMPIInt tag[], PetscMPIInt rank, void *rdata, MPI_Request req[], void *ctx)
154: {
155:   Vec                X   = (Vec)ctx;
156:   Vec_MPI           *x   = (Vec_MPI *)X->data;
157:   VecAssemblyHeader *hdr = (VecAssemblyHeader *)rdata;
158:   PetscInt           bs  = X->map->bs;
159:   VecAssemblyFrame  *frame;

161:   PetscFunctionBegin;
162:   PetscCall(PetscSegBufferGet(x->segrecvframe, 1, &frame));

164:   if (hdr->count) {
165:     PetscCall(PetscSegBufferGet(x->segrecvint, hdr->count, &frame->ints));
166:     PetscCallMPI(MPI_Irecv(frame->ints, hdr->count, MPIU_INT, rank, tag[0], comm, &req[0]));
167:     PetscCall(PetscSegBufferGet(x->segrecvscalar, hdr->count, &frame->scalars));
168:     PetscCallMPI(MPI_Irecv(frame->scalars, hdr->count, MPIU_SCALAR, rank, tag[1], comm, &req[1]));
169:     frame->pendings = 2;
170:   } else {
171:     frame->ints     = NULL;
172:     frame->scalars  = NULL;
173:     frame->pendings = 0;
174:   }

176:   if (hdr->bcount) {
177:     PetscCall(PetscSegBufferGet(x->segrecvint, hdr->bcount, &frame->intb));
178:     PetscCallMPI(MPI_Irecv(frame->intb, hdr->bcount, MPIU_INT, rank, tag[2], comm, &req[2]));
179:     PetscCall(PetscSegBufferGet(x->segrecvscalar, hdr->bcount * bs, &frame->scalarb));
180:     PetscCallMPI(MPI_Irecv(frame->scalarb, hdr->bcount * bs, MPIU_SCALAR, rank, tag[3], comm, &req[3]));
181:     frame->pendingb = 2;
182:   } else {
183:     frame->intb     = NULL;
184:     frame->scalarb  = NULL;
185:     frame->pendingb = 0;
186:   }
187:   PetscFunctionReturn(PETSC_SUCCESS);
188: }

190: static PetscErrorCode VecAssemblyBegin_MPI_BTS(Vec X)
191: {
192:   Vec_MPI *x = (Vec_MPI *)X->data;
193:   MPI_Comm comm;
194:   PetscInt i, j, jb, bs;

196:   PetscFunctionBegin;
197:   if (X->stash.donotstash) PetscFunctionReturn(PETSC_SUCCESS);

199:   PetscCall(PetscObjectGetComm((PetscObject)X, &comm));
200:   PetscCall(VecGetBlockSize(X, &bs));
201:   if (PetscDefined(USE_DEBUG)) {
202:     InsertMode addv;
203:     PetscCall(MPIU_Allreduce((PetscEnum *)&X->stash.insertmode, (PetscEnum *)&addv, 1, MPIU_ENUM, MPI_BOR, comm));
204:     PetscCheck(addv != (ADD_VALUES | INSERT_VALUES), comm, PETSC_ERR_ARG_NOTSAMETYPE, "Some processors inserted values while others added");
205:   }
206:   X->bstash.insertmode = X->stash.insertmode; /* Block stash implicitly tracks InsertMode of scalar stash */

208:   PetscCall(VecStashSortCompress_Private(&X->stash));
209:   PetscCall(VecStashSortCompress_Private(&X->bstash));

211:   if (!x->sendranks) {
212:     PetscMPIInt nowners, bnowners, *owners, *bowners;
213:     PetscInt    ntmp;
214:     PetscCall(VecStashGetOwnerList_Private(&X->stash, X->map, &nowners, &owners));
215:     PetscCall(VecStashGetOwnerList_Private(&X->bstash, X->map, &bnowners, &bowners));
216:     PetscCall(PetscMergeMPIIntArray(nowners, owners, bnowners, bowners, &ntmp, &x->sendranks));
217:     x->nsendranks = ntmp;
218:     PetscCall(PetscFree(owners));
219:     PetscCall(PetscFree(bowners));
220:     PetscCall(PetscMalloc1(x->nsendranks, &x->sendhdr));
221:     PetscCall(PetscCalloc1(x->nsendranks, &x->sendptrs));
222:   }
223:   for (i = 0, j = 0, jb = 0; i < x->nsendranks; i++) {
224:     PetscMPIInt rank         = x->sendranks[i];
225:     x->sendhdr[i].insertmode = X->stash.insertmode;
226:     /* Initialize pointers for non-empty stashes the first time around.  Subsequent assemblies with
227:      * VEC_SUBSET_OFF_PROC_ENTRIES will leave the old pointers (dangling because the stash has been collected) when
228:      * there is nothing new to send, so that size-zero messages get sent instead. */
229:     x->sendhdr[i].count = 0;
230:     if (X->stash.n) {
231:       x->sendptrs[i].ints    = &X->stash.idx[j];
232:       x->sendptrs[i].scalars = &X->stash.array[j];
233:       for (; j < X->stash.n && X->stash.idx[j] < X->map->range[rank + 1]; j++) x->sendhdr[i].count++;
234:     }
235:     x->sendhdr[i].bcount = 0;
236:     if (X->bstash.n) {
237:       x->sendptrs[i].intb    = &X->bstash.idx[jb];
238:       x->sendptrs[i].scalarb = &X->bstash.array[jb * bs];
239:       for (; jb < X->bstash.n && X->bstash.idx[jb] * bs < X->map->range[rank + 1]; jb++) x->sendhdr[i].bcount++;
240:     }
241:   }

243:   if (!x->segrecvint) PetscCall(PetscSegBufferCreate(sizeof(PetscInt), 1000, &x->segrecvint));
244:   if (!x->segrecvscalar) PetscCall(PetscSegBufferCreate(sizeof(PetscScalar), 1000, &x->segrecvscalar));
245:   if (!x->segrecvframe) PetscCall(PetscSegBufferCreate(sizeof(VecAssemblyFrame), 50, &x->segrecvframe));
246:   if (x->first_assembly_done) { /* this is not the first assembly */
247:     PetscMPIInt tag[4];
248:     for (i = 0; i < 4; i++) PetscCall(PetscCommGetNewTag(comm, &tag[i]));
249:     for (i = 0; i < x->nsendranks; i++) PetscCall(VecAssemblySend_MPI_Private(comm, tag, i, x->sendranks[i], x->sendhdr + i, x->sendreqs + 4 * i, X));
250:     for (i = 0; i < x->nrecvranks; i++) PetscCall(VecAssemblyRecv_MPI_Private(comm, tag, x->recvranks[i], x->recvhdr + i, x->recvreqs + 4 * i, X));
251:     x->use_status = PETSC_TRUE;
252:   } else { /* First time assembly */
253:     PetscCall(PetscCommBuildTwoSidedFReq(comm, 3, MPIU_INT, x->nsendranks, x->sendranks, (PetscInt *)x->sendhdr, &x->nrecvranks, &x->recvranks, &x->recvhdr, 4, &x->sendreqs, &x->recvreqs, VecAssemblySend_MPI_Private, VecAssemblyRecv_MPI_Private, X));
254:     x->use_status = PETSC_FALSE;
255:   }

257:   /* The first_assembly_done flag is only meaningful when x->assembly_subset is set.
258:      This line says when assembly_subset is set, then we mark that the first assembly is done.
259:    */
260:   x->first_assembly_done = x->assembly_subset;

262:   {
263:     PetscInt nstash, reallocs;
264:     PetscCall(VecStashGetInfo_Private(&X->stash, &nstash, &reallocs));
265:     PetscCall(PetscInfo(X, "Stash has %" PetscInt_FMT " entries, uses %" PetscInt_FMT " mallocs.\n", nstash, reallocs));
266:     PetscCall(VecStashGetInfo_Private(&X->bstash, &nstash, &reallocs));
267:     PetscCall(PetscInfo(X, "Block-Stash has %" PetscInt_FMT " entries, uses %" PetscInt_FMT " mallocs.\n", nstash, reallocs));
268:   }
269:   PetscFunctionReturn(PETSC_SUCCESS);
270: }

272: static PetscErrorCode VecAssemblyEnd_MPI_BTS(Vec X)
273: {
274:   Vec_MPI          *x  = (Vec_MPI *)X->data;
275:   PetscInt          bs = X->map->bs;
276:   PetscMPIInt       npending, *some_indices, r;
277:   MPI_Status       *some_statuses;
278:   PetscScalar      *xarray;
279:   VecAssemblyFrame *frame;

281:   PetscFunctionBegin;
282:   if (X->stash.donotstash) {
283:     X->stash.insertmode  = NOT_SET_VALUES;
284:     X->bstash.insertmode = NOT_SET_VALUES;
285:     PetscFunctionReturn(PETSC_SUCCESS);
286:   }

288:   PetscCheck(x->segrecvframe, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing segrecvframe! Probably you forgot to call VecAssemblyBegin() first");
289:   PetscCall(VecGetArray(X, &xarray));
290:   PetscCall(PetscSegBufferExtractInPlace(x->segrecvframe, &frame));
291:   PetscCall(PetscMalloc2(4 * x->nrecvranks, &some_indices, x->use_status ? 4 * x->nrecvranks : 0, &some_statuses));
292:   for (r = 0, npending = 0; r < x->nrecvranks; r++) npending += frame[r].pendings + frame[r].pendingb;
293:   while (npending > 0) {
294:     PetscMPIInt ndone = 0, ii;
295:     /* Filling MPI_Status fields requires some resources from the MPI library.  We skip it on the first assembly, or
296:      * when VEC_SUBSET_OFF_PROC_ENTRIES has not been set, because we could exchange exact sizes in the initial
297:      * rendezvous.  When the rendezvous is elided, however, we use MPI_Status to get actual message lengths, so that
298:      * subsequent assembly can set a proper subset of the values. */
299:     PetscCallMPI(MPI_Waitsome(4 * x->nrecvranks, x->recvreqs, &ndone, some_indices, x->use_status ? some_statuses : MPI_STATUSES_IGNORE));
300:     for (ii = 0; ii < ndone; ii++) {
301:       PetscInt     i     = some_indices[ii] / 4, j, k;
302:       InsertMode   imode = (InsertMode)x->recvhdr[i].insertmode;
303:       PetscInt    *recvint;
304:       PetscScalar *recvscalar;
305:       PetscBool    intmsg   = (PetscBool)(some_indices[ii] % 2 == 0);
306:       PetscBool    blockmsg = (PetscBool)((some_indices[ii] % 4) / 2 == 1);
307:       npending--;
308:       if (!blockmsg) { /* Scalar stash */
309:         PetscMPIInt count;
310:         if (--frame[i].pendings > 0) continue;
311:         if (x->use_status) {
312:           PetscCallMPI(MPI_Get_count(&some_statuses[ii], intmsg ? MPIU_INT : MPIU_SCALAR, &count));
313:         } else count = x->recvhdr[i].count;
314:         for (j = 0, recvint = frame[i].ints, recvscalar = frame[i].scalars; j < count; j++, recvint++) {
315:           PetscInt loc = *recvint - X->map->rstart;
316:           PetscCheck(*recvint >= X->map->rstart && X->map->rend > *recvint, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Received vector entry %" PetscInt_FMT " out of local range [%" PetscInt_FMT ",%" PetscInt_FMT ")]", *recvint, X->map->rstart, X->map->rend);
317:           switch (imode) {
318:           case ADD_VALUES:
319:             xarray[loc] += *recvscalar++;
320:             break;
321:           case INSERT_VALUES:
322:             xarray[loc] = *recvscalar++;
323:             break;
324:           default:
325:             SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Insert mode not supported 0x%x", imode);
326:           }
327:         }
328:       } else { /* Block stash */
329:         PetscMPIInt count;
330:         if (--frame[i].pendingb > 0) continue;
331:         if (x->use_status) {
332:           PetscCallMPI(MPI_Get_count(&some_statuses[ii], intmsg ? MPIU_INT : MPIU_SCALAR, &count));
333:           if (!intmsg) count /= bs; /* Convert from number of scalars to number of blocks */
334:         } else count = x->recvhdr[i].bcount;
335:         for (j = 0, recvint = frame[i].intb, recvscalar = frame[i].scalarb; j < count; j++, recvint++) {
336:           PetscInt loc = (*recvint) * bs - X->map->rstart;
337:           switch (imode) {
338:           case ADD_VALUES:
339:             for (k = loc; k < loc + bs; k++) xarray[k] += *recvscalar++;
340:             break;
341:           case INSERT_VALUES:
342:             for (k = loc; k < loc + bs; k++) xarray[k] = *recvscalar++;
343:             break;
344:           default:
345:             SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Insert mode not supported 0x%x", imode);
346:           }
347:         }
348:       }
349:     }
350:   }
351:   PetscCall(VecRestoreArray(X, &xarray));
352:   PetscCallMPI(MPI_Waitall(4 * x->nsendranks, x->sendreqs, MPI_STATUSES_IGNORE));
353:   PetscCall(PetscFree2(some_indices, some_statuses));
354:   if (x->assembly_subset) {
355:     PetscCall(PetscSegBufferExtractInPlace(x->segrecvint, NULL));
356:     PetscCall(PetscSegBufferExtractInPlace(x->segrecvscalar, NULL));
357:   } else {
358:     PetscCall(VecAssemblyReset_MPI(X));
359:   }

361:   X->stash.insertmode  = NOT_SET_VALUES;
362:   X->bstash.insertmode = NOT_SET_VALUES;
363:   PetscCall(VecStashScatterEnd_Private(&X->stash));
364:   PetscCall(VecStashScatterEnd_Private(&X->bstash));
365:   PetscFunctionReturn(PETSC_SUCCESS);
366: }

368: PetscErrorCode VecAssemblyReset_MPI(Vec X)
369: {
370:   Vec_MPI *x = (Vec_MPI *)X->data;

372:   PetscFunctionBegin;
373:   PetscCall(PetscFree(x->sendreqs));
374:   PetscCall(PetscFree(x->recvreqs));
375:   PetscCall(PetscFree(x->sendranks));
376:   PetscCall(PetscFree(x->recvranks));
377:   PetscCall(PetscFree(x->sendhdr));
378:   PetscCall(PetscFree(x->recvhdr));
379:   PetscCall(PetscFree(x->sendptrs));
380:   PetscCall(PetscSegBufferDestroy(&x->segrecvint));
381:   PetscCall(PetscSegBufferDestroy(&x->segrecvscalar));
382:   PetscCall(PetscSegBufferDestroy(&x->segrecvframe));
383:   PetscFunctionReturn(PETSC_SUCCESS);
384: }

386: static PetscErrorCode VecSetFromOptions_MPI(Vec X, PetscOptionItems *PetscOptionsObject)
387: {
388: #if !defined(PETSC_HAVE_MPIUNI)
389:   PetscBool flg = PETSC_FALSE, set;

391:   PetscFunctionBegin;
392:   PetscOptionsHeadBegin(PetscOptionsObject, "VecMPI Options");
393:   PetscCall(PetscOptionsBool("-vec_assembly_legacy", "Use MPI 1 version of assembly", "", flg, &flg, &set));
394:   if (set) {
395:     X->ops->assemblybegin = flg ? VecAssemblyBegin_MPI : VecAssemblyBegin_MPI_BTS;
396:     X->ops->assemblyend   = flg ? VecAssemblyEnd_MPI : VecAssemblyEnd_MPI_BTS;
397:   }
398:   PetscOptionsHeadEnd();
399: #else
400:   PetscFunctionBegin;
401:   X->ops->assemblybegin = VecAssemblyBegin_MPI;
402:   X->ops->assemblyend   = VecAssemblyEnd_MPI;
403: #endif
404:   PetscFunctionReturn(PETSC_SUCCESS);
405: }

407: static PetscErrorCode VecGetLocalToGlobalMapping_MPI_VecGhost(Vec X, ISLocalToGlobalMapping *ltg)
408: {
409:   PetscInt       *indices, n, nghost, rstart, i;
410:   IS              ghostis;
411:   const PetscInt *ghostidx;

413:   PetscFunctionBegin;
414:   if (X->map->mapping) {
415:     *ltg = X->map->mapping;
416:     PetscFunctionReturn(PETSC_SUCCESS);
417:   }
418:   PetscCall(VecGhostGetGhostIS(X, &ghostis));
419:   PetscCall(ISGetLocalSize(ghostis, &nghost));
420:   PetscCall(VecGetLocalSize(X, &n));
421:   PetscCall(ISGetIndices(ghostis, &ghostidx));
422:   /* set local to global mapping for ghosted vector */
423:   PetscCall(PetscMalloc1(n + nghost, &indices));
424:   PetscCall(VecGetOwnershipRange(X, &rstart, NULL));
425:   for (i = 0; i < n; i++) indices[i] = rstart + i;
426:   PetscCall(PetscArraycpy(indices + n, ghostidx, nghost));
427:   PetscCall(ISRestoreIndices(ghostis, &ghostidx));
428:   PetscCall(ISLocalToGlobalMappingCreate(PETSC_COMM_SELF, 1, n + nghost, indices, PETSC_OWN_POINTER, &X->map->mapping));
429:   *ltg = X->map->mapping;
430:   PetscFunctionReturn(PETSC_SUCCESS);
431: }

433: static struct _VecOps DvOps = {PetscDesignatedInitializer(duplicate, VecDuplicate_MPI), /* 1 */
434:                                PetscDesignatedInitializer(duplicatevecs, VecDuplicateVecs_Default),
435:                                PetscDesignatedInitializer(destroyvecs, VecDestroyVecs_Default),
436:                                PetscDesignatedInitializer(dot, VecDot_MPI),
437:                                PetscDesignatedInitializer(mdot, VecMDot_MPI),
438:                                PetscDesignatedInitializer(norm, VecNorm_MPI),
439:                                PetscDesignatedInitializer(tdot, VecTDot_MPI),
440:                                PetscDesignatedInitializer(mtdot, VecMTDot_MPI),
441:                                PetscDesignatedInitializer(scale, VecScale_Seq),
442:                                PetscDesignatedInitializer(copy, VecCopy_Seq), /* 10 */
443:                                PetscDesignatedInitializer(set, VecSet_Seq),
444:                                PetscDesignatedInitializer(swap, VecSwap_Seq),
445:                                PetscDesignatedInitializer(axpy, VecAXPY_Seq),
446:                                PetscDesignatedInitializer(axpby, VecAXPBY_Seq),
447:                                PetscDesignatedInitializer(maxpy, VecMAXPY_Seq),
448:                                PetscDesignatedInitializer(aypx, VecAYPX_Seq),
449:                                PetscDesignatedInitializer(waxpy, VecWAXPY_Seq),
450:                                PetscDesignatedInitializer(axpbypcz, VecAXPBYPCZ_Seq),
451:                                PetscDesignatedInitializer(pointwisemult, VecPointwiseMult_Seq),
452:                                PetscDesignatedInitializer(pointwisedivide, VecPointwiseDivide_Seq),
453:                                PetscDesignatedInitializer(setvalues, VecSetValues_MPI), /* 20 */
454:                                PetscDesignatedInitializer(assemblybegin, VecAssemblyBegin_MPI_BTS),
455:                                PetscDesignatedInitializer(assemblyend, VecAssemblyEnd_MPI_BTS),
456:                                PetscDesignatedInitializer(getarray, NULL),
457:                                PetscDesignatedInitializer(getsize, VecGetSize_MPI),
458:                                PetscDesignatedInitializer(getlocalsize, VecGetSize_Seq),
459:                                PetscDesignatedInitializer(restorearray, NULL),
460:                                PetscDesignatedInitializer(max, VecMax_MPI),
461:                                PetscDesignatedInitializer(min, VecMin_MPI),
462:                                PetscDesignatedInitializer(setrandom, VecSetRandom_Seq),
463:                                PetscDesignatedInitializer(setoption, VecSetOption_MPI),
464:                                PetscDesignatedInitializer(setvaluesblocked, VecSetValuesBlocked_MPI),
465:                                PetscDesignatedInitializer(destroy, VecDestroy_MPI),
466:                                PetscDesignatedInitializer(view, VecView_MPI),
467:                                PetscDesignatedInitializer(placearray, VecPlaceArray_MPI),
468:                                PetscDesignatedInitializer(replacearray, VecReplaceArray_Seq),
469:                                PetscDesignatedInitializer(dot_local, VecDot_Seq),
470:                                PetscDesignatedInitializer(tdot_local, VecTDot_Seq),
471:                                PetscDesignatedInitializer(norm_local, VecNorm_Seq),
472:                                PetscDesignatedInitializer(mdot_local, VecMDot_Seq),
473:                                PetscDesignatedInitializer(mtdot_local, VecMTDot_Seq),
474:                                PetscDesignatedInitializer(load, VecLoad_Default),
475:                                PetscDesignatedInitializer(reciprocal, VecReciprocal_Default),
476:                                PetscDesignatedInitializer(conjugate, VecConjugate_Seq),
477:                                PetscDesignatedInitializer(setlocaltoglobalmapping, NULL),
478:                                PetscDesignatedInitializer(getlocaltoglobalmapping, VecGetLocalToGlobalMapping_MPI_VecGhost),
479:                                PetscDesignatedInitializer(setvalueslocal, NULL),
480:                                PetscDesignatedInitializer(resetarray, VecResetArray_MPI),
481:                                PetscDesignatedInitializer(setfromoptions, VecSetFromOptions_MPI), /*set from options */
482:                                PetscDesignatedInitializer(maxpointwisedivide, VecMaxPointwiseDivide_Seq),
483:                                PetscDesignatedInitializer(pointwisemax, VecPointwiseMax_Seq),
484:                                PetscDesignatedInitializer(pointwisemaxabs, VecPointwiseMaxAbs_Seq),
485:                                PetscDesignatedInitializer(pointwisemin, VecPointwiseMin_Seq),
486:                                PetscDesignatedInitializer(getvalues, VecGetValues_MPI),
487:                                PetscDesignatedInitializer(sqrt, NULL),
488:                                PetscDesignatedInitializer(abs, NULL),
489:                                PetscDesignatedInitializer(exp, NULL),
490:                                PetscDesignatedInitializer(log, NULL),
491:                                PetscDesignatedInitializer(shift, NULL),
492:                                PetscDesignatedInitializer(create, NULL), /* really? */
493:                                PetscDesignatedInitializer(stridegather, VecStrideGather_Default),
494:                                PetscDesignatedInitializer(stridescatter, VecStrideScatter_Default),
495:                                PetscDesignatedInitializer(dotnorm2, NULL),
496:                                PetscDesignatedInitializer(getsubvector, NULL),
497:                                PetscDesignatedInitializer(restoresubvector, NULL),
498:                                PetscDesignatedInitializer(getarrayread, NULL),
499:                                PetscDesignatedInitializer(restorearrayread, NULL),
500:                                PetscDesignatedInitializer(stridesubsetgather, VecStrideSubSetGather_Default),
501:                                PetscDesignatedInitializer(stridesubsetscatter, VecStrideSubSetScatter_Default),
502:                                PetscDesignatedInitializer(viewnative, VecView_MPI),
503:                                PetscDesignatedInitializer(loadnative, NULL),
504:                                PetscDesignatedInitializer(createlocalvector, NULL),
505:                                PetscDesignatedInitializer(getlocalvector, NULL),
506:                                PetscDesignatedInitializer(restorelocalvector, NULL),
507:                                PetscDesignatedInitializer(getlocalvectorread, NULL),
508:                                PetscDesignatedInitializer(restorelocalvectorread, NULL),
509:                                PetscDesignatedInitializer(bindtocpu, NULL),
510:                                PetscDesignatedInitializer(getarraywrite, NULL),
511:                                PetscDesignatedInitializer(restorearraywrite, NULL),
512:                                PetscDesignatedInitializer(getarrayandmemtype, NULL),
513:                                PetscDesignatedInitializer(restorearrayandmemtype, NULL),
514:                                PetscDesignatedInitializer(getarrayreadandmemtype, NULL),
515:                                PetscDesignatedInitializer(restorearrayreadandmemtype, NULL),
516:                                PetscDesignatedInitializer(getarraywriteandmemtype, NULL),
517:                                PetscDesignatedInitializer(restorearraywriteandmemtype, NULL),
518:                                PetscDesignatedInitializer(concatenate, NULL),
519:                                PetscDesignatedInitializer(sum, NULL),
520:                                PetscDesignatedInitializer(setpreallocationcoo, VecSetPreallocationCOO_MPI),
521:                                PetscDesignatedInitializer(setvaluescoo, VecSetValuesCOO_MPI),
522:                                PetscDesignatedInitializer(errorwnorm, NULL)};

524: /*
525:     VecCreate_MPI_Private - Basic create routine called by VecCreate_MPI() (i.e. VecCreateMPI()),
526:     VecCreateMPIWithArray(), VecCreate_Shared() (i.e. VecCreateShared()), VecCreateGhost(),
527:     VecDuplicate_MPI(), VecCreateGhostWithArray(), VecDuplicate_MPI(), and VecDuplicate_Shared()

529:     If alloc is true and array is NULL then this routine allocates the space, otherwise
530:     no space is allocated.
531: */
532: PetscErrorCode VecCreate_MPI_Private(Vec v, PetscBool alloc, PetscInt nghost, const PetscScalar array[])
533: {
534:   Vec_MPI  *s;
535:   PetscBool mdot_use_gemv  = PETSC_TRUE;
536:   PetscBool maxpy_use_gemv = PETSC_FALSE; // default is false as we saw bad performance with vendors' GEMV with tall skinny matrices.

538:   PetscFunctionBegin;
539:   PetscCall(PetscNew(&s));
540:   v->data   = (void *)s;
541:   v->ops[0] = DvOps;

543:   PetscCall(PetscOptionsGetBool(NULL, NULL, "-vec_mdot_use_gemv", &mdot_use_gemv, NULL));
544:   PetscCall(PetscOptionsGetBool(NULL, NULL, "-vec_maxpy_use_gemv", &maxpy_use_gemv, NULL));

546:   // allocate multiple vectors together
547:   if (mdot_use_gemv || maxpy_use_gemv) v->ops[0].duplicatevecs = VecDuplicateVecs_MPI_GEMV;

549:   if (mdot_use_gemv) {
550:     v->ops[0].mdot        = VecMDot_MPI_GEMV;
551:     v->ops[0].mdot_local  = VecMDot_Seq_GEMV;
552:     v->ops[0].mtdot       = VecMTDot_MPI_GEMV;
553:     v->ops[0].mtdot_local = VecMTDot_Seq_GEMV;
554:   }
555:   if (maxpy_use_gemv) v->ops[0].maxpy = VecMAXPY_Seq_GEMV;

557:   s->nghost      = nghost;
558:   v->petscnative = PETSC_TRUE;
559:   if (array) v->offloadmask = PETSC_OFFLOAD_CPU;

561:   PetscCall(PetscLayoutSetUp(v->map));

563:   s->array           = (PetscScalar *)array;
564:   s->array_allocated = NULL;
565:   if (alloc && !array) {
566:     PetscInt n = v->map->n + nghost;
567:     PetscCall(PetscCalloc1(n, &s->array));
568:     s->array_allocated = s->array;
569:     PetscCall(PetscObjectComposedDataSetReal((PetscObject)v, NormIds[NORM_2], 0));
570:     PetscCall(PetscObjectComposedDataSetReal((PetscObject)v, NormIds[NORM_1], 0));
571:     PetscCall(PetscObjectComposedDataSetReal((PetscObject)v, NormIds[NORM_INFINITY], 0));
572:   }

574:   /* By default parallel vectors do not have local representation */
575:   s->localrep    = NULL;
576:   s->localupdate = NULL;
577:   s->ghost       = NULL;

579:   v->stash.insertmode  = NOT_SET_VALUES;
580:   v->bstash.insertmode = NOT_SET_VALUES;
581:   /* create the stashes. The block-size for bstash is set later when
582:      VecSetValuesBlocked is called.
583:   */
584:   PetscCall(VecStashCreate_Private(PetscObjectComm((PetscObject)v), 1, &v->stash));
585:   PetscCall(VecStashCreate_Private(PetscObjectComm((PetscObject)v), PetscAbs(v->map->bs), &v->bstash));

587: #if defined(PETSC_HAVE_MATLAB)
588:   PetscCall(PetscObjectComposeFunction((PetscObject)v, "PetscMatlabEnginePut_C", VecMatlabEnginePut_Default));
589:   PetscCall(PetscObjectComposeFunction((PetscObject)v, "PetscMatlabEngineGet_C", VecMatlabEngineGet_Default));
590: #endif
591:   PetscCall(PetscObjectChangeTypeName((PetscObject)v, VECMPI));
592:   PetscFunctionReturn(PETSC_SUCCESS);
593: }

595: /*
596:   Create a VECMPI with the given layout and array

598:   Collective

600:   Input Parameter:
601: + map   - the layout
602: - array - the array on host

604:   Output Parameter:
605: . V  - The vector object
606: */
607: PetscErrorCode VecCreateMPIWithLayoutAndArray_Private(PetscLayout map, const PetscScalar array[], Vec *V)
608: {
609:   PetscFunctionBegin;
610:   PetscCall(VecCreateWithLayout_Private(map, V));
611:   PetscCall(VecCreate_MPI_Private(*V, PETSC_FALSE, 0, array));
612:   PetscFunctionReturn(PETSC_SUCCESS);
613: }

615: /*MC
616:    VECMPI - VECMPI = "mpi" - The basic parallel vector

618:    Options Database Key:
619: . -vec_type mpi - sets the vector type to `VECMPI` during a call to `VecSetFromOptions()`

621:   Level: beginner

623: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreate()`, `VecSetType()`, `VecSetFromOptions()`, `VecCreateMPIWithArray()`, `VECMPI`, `VecType`, `VecCreateMPI()`, `VecCreateMPI()`
624: M*/

626: PetscErrorCode VecCreate_MPI(Vec vv)
627: {
628:   PetscFunctionBegin;
629:   PetscCall(VecCreate_MPI_Private(vv, PETSC_TRUE, 0, NULL));
630:   PetscFunctionReturn(PETSC_SUCCESS);
631: }

633: /*MC
634:    VECSTANDARD = "standard" - A `VECSEQ` on one process and `VECMPI` on more than one process

636:    Options Database Key:
637: . -vec_type standard - sets a vector type to standard on calls to `VecSetFromOptions()`

639:   Level: beginner

641: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreateSeq()`, `VecCreateMPI()`
642: M*/

644: PETSC_EXTERN PetscErrorCode VecCreate_Standard(Vec v)
645: {
646:   PetscMPIInt size;

648:   PetscFunctionBegin;
649:   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)v), &size));
650:   if (size == 1) {
651:     PetscCall(VecSetType(v, VECSEQ));
652:   } else {
653:     PetscCall(VecSetType(v, VECMPI));
654:   }
655:   PetscFunctionReturn(PETSC_SUCCESS);
656: }

658: /*@C
659:   VecCreateMPIWithArray - Creates a parallel, array-style vector,
660:   where the user provides the array space to store the vector values.

662:   Collective

664:   Input Parameters:
665: + comm  - the MPI communicator to use
666: . bs    - block size, same meaning as `VecSetBlockSize()`
667: . n     - local vector length, cannot be `PETSC_DECIDE`
668: . N     - global vector length (or `PETSC_DETERMINE` to have calculated)
669: - array - the user provided array to store the vector values

671:   Output Parameter:
672: . vv - the vector

674:   Level: intermediate

676:   Notes:
677:   Use `VecDuplicate()` or `VecDuplicateVecs()` to form additional vectors of the
678:   same type as an existing vector.

680:   If the user-provided array is `NULL`, then `VecPlaceArray()` can be used
681:   at a later stage to SET the array for storing the vector values.

683:   PETSc does NOT free `array` when the vector is destroyed via `VecDestroy()`.

685:   The user should not free `array` until the vector is destroyed.

687: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreateSeqWithArray()`, `VecCreate()`, `VecDuplicate()`, `VecDuplicateVecs()`, `VecCreateGhost()`,
688:           `VecCreateMPI()`, `VecCreateGhostWithArray()`, `VecPlaceArray()`
689: @*/
690: PetscErrorCode VecCreateMPIWithArray(MPI_Comm comm, PetscInt bs, PetscInt n, PetscInt N, const PetscScalar array[], Vec *vv)
691: {
692:   PetscFunctionBegin;
693:   PetscCheck(n != PETSC_DECIDE, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Must set local size of vector");
694:   PetscCall(PetscSplitOwnership(comm, &n, &N));
695:   PetscCall(VecCreate(comm, vv));
696:   PetscCall(VecSetSizes(*vv, n, N));
697:   PetscCall(VecSetBlockSize(*vv, bs));
698:   PetscCall(VecCreate_MPI_Private(*vv, PETSC_FALSE, 0, array));
699:   PetscFunctionReturn(PETSC_SUCCESS);
700: }

702: /*@C
703:   VecCreateGhostWithArray - Creates a parallel vector with ghost padding on each processor;
704:   the caller allocates the array space.

706:   Collective

708:   Input Parameters:
709: + comm   - the MPI communicator to use
710: . n      - local vector length
711: . N      - global vector length (or `PETSC_DETERMINE` to have calculated if `n` is given)
712: . nghost - number of local ghost points
713: . ghosts - global indices of ghost points (or `NULL` if not needed), these do not need to be in increasing order (sorted)
714: - array  - the space to store the vector values (as long as n + nghost)

716:   Output Parameter:
717: . vv - the global vector representation (without ghost points as part of vector)

719:   Level: advanced

721:   Notes:
722:   Use `VecGhostGetLocalForm()` to access the local, ghosted representation
723:   of the vector.

725:   This also automatically sets the `ISLocalToGlobalMapping()` for this vector.

727: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreate()`, `VecGhostGetLocalForm()`, `VecGhostRestoreLocalForm()`,
728:           `VecCreateGhost()`, `VecCreateSeqWithArray()`, `VecCreateMPIWithArray()`,
729:           `VecCreateGhostBlock()`, `VecCreateGhostBlockWithArray()`, `VecMPISetGhost()`
730: @*/
731: PetscErrorCode VecCreateGhostWithArray(MPI_Comm comm, PetscInt n, PetscInt N, PetscInt nghost, const PetscInt ghosts[], const PetscScalar array[], Vec *vv)
732: {
733:   Vec_MPI     *w;
734:   PetscScalar *larray;
735:   IS           from, to;

737:   PetscFunctionBegin;
738:   *vv = NULL;
739:   PetscCheck(nghost != PETSC_DECIDE, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Must set local ghost size");
740:   PetscCheck(nghost >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Ghost length must be >= 0");
741:   PetscCall(PetscSplitOwnership(comm, &n, &N));
742:   /* Create global representation */
743:   PetscCall(VecCreate(comm, vv));
744:   PetscCall(VecSetSizes(*vv, n, N));
745:   PetscCall(VecCreate_MPI_Private(*vv, PETSC_TRUE, nghost, array));
746:   w = (Vec_MPI *)(*vv)->data;
747:   /* Create local representation */
748:   PetscCall(VecGetArray(*vv, &larray));
749:   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, n + nghost, larray, &w->localrep));
750:   PetscCall(VecRestoreArray(*vv, &larray));

752:   /*
753:        Create scatter context for scattering (updating) ghost values
754:   */
755:   PetscCall(ISCreateGeneral(comm, nghost, ghosts, PETSC_COPY_VALUES, &from));
756:   PetscCall(ISCreateStride(PETSC_COMM_SELF, nghost, n, 1, &to));
757:   PetscCall(VecScatterCreate(*vv, from, w->localrep, to, &w->localupdate));
758:   PetscCall(ISDestroy(&to));

760:   w->ghost                            = from;
761:   (*vv)->ops->getlocaltoglobalmapping = VecGetLocalToGlobalMapping_MPI_VecGhost;
762:   PetscFunctionReturn(PETSC_SUCCESS);
763: }

765: /*@
766:   VecGhostGetGhostIS - Return ghosting indices of a ghost vector

768:   Input Parameters:
769: . X - ghost vector

771:   Output Parameter:
772: . ghost - ghosting indices

774:   Level: beginner

776: .seealso: `VecCreateGhostWithArray()`, `VecCreateMPIWithArray()`
777: @*/
778: PetscErrorCode VecGhostGetGhostIS(Vec X, IS *ghost)
779: {
780:   Vec_MPI  *w;
781:   PetscBool flg;

783:   PetscFunctionBegin;
785:   PetscAssertPointer(ghost, 2);
786:   PetscCall(PetscObjectTypeCompare((PetscObject)X, VECMPI, &flg));
787:   PetscCheck(flg, PetscObjectComm((PetscObject)X), PETSC_ERR_ARG_WRONGSTATE, "VecGhostGetGhostIS was not supported for vec type %s", ((PetscObject)X)->type_name);
788:   w      = (Vec_MPI *)(X)->data;
789:   *ghost = w->ghost;
790:   PetscFunctionReturn(PETSC_SUCCESS);
791: }

793: /*@
794:   VecCreateGhost - Creates a parallel vector with ghost padding on each processor.

796:   Collective

798:   Input Parameters:
799: + comm   - the MPI communicator to use
800: . n      - local vector length
801: . N      - global vector length (or `PETSC_DETERMINE` to have calculated if `n` is given)
802: . nghost - number of local ghost points
803: - ghosts - global indices of ghost points, these do not need to be in increasing order (sorted)

805:   Output Parameter:
806: . vv - the global vector representation (without ghost points as part of vector)

808:   Level: advanced

810:   Notes:
811:   Use `VecGhostGetLocalForm()` to access the local, ghosted representation
812:   of the vector.

814:   This also automatically sets the `ISLocalToGlobalMapping()` for this vector.

816: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreateSeq()`, `VecCreate()`, `VecDuplicate()`, `VecDuplicateVecs()`, `VecCreateMPI()`,
817:           `VecGhostGetLocalForm()`, `VecGhostRestoreLocalForm()`, `VecGhostUpdateBegin()`,
818:           `VecCreateGhostWithArray()`, `VecCreateMPIWithArray()`, `VecGhostUpdateEnd()`,
819:           `VecCreateGhostBlock()`, `VecCreateGhostBlockWithArray()`, `VecMPISetGhost()`

821: @*/
822: PetscErrorCode VecCreateGhost(MPI_Comm comm, PetscInt n, PetscInt N, PetscInt nghost, const PetscInt ghosts[], Vec *vv)
823: {
824:   PetscFunctionBegin;
825:   PetscCall(VecCreateGhostWithArray(comm, n, N, nghost, ghosts, NULL, vv));
826:   PetscFunctionReturn(PETSC_SUCCESS);
827: }

829: /*@
830:   VecMPISetGhost - Sets the ghost points for an MPI ghost vector

832:   Collective

834:   Input Parameters:
835: + vv     - the MPI vector
836: . nghost - number of local ghost points
837: - ghosts - global indices of ghost points, these do not need to be in increasing order (sorted)

839:   Level: advanced

841:   Notes:
842:   Use `VecGhostGetLocalForm()` to access the local, ghosted representation
843:   of the vector.

845:   This also automatically sets the `ISLocalToGlobalMapping()` for this vector.

847:   You must call this AFTER you have set the type of the vector (with` VecSetType()`) and the size (with `VecSetSizes()`).

849: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreateSeq()`, `VecCreate()`, `VecDuplicate()`, `VecDuplicateVecs()`, `VecCreateMPI()`,
850:           `VecGhostGetLocalForm()`, `VecGhostRestoreLocalForm()`, `VecGhostUpdateBegin()`,
851:           `VecCreateGhostWithArray()`, `VecCreateMPIWithArray()`, `VecGhostUpdateEnd()`,
852:           `VecCreateGhostBlock()`, `VecCreateGhostBlockWithArray()`
853: @*/
854: PetscErrorCode VecMPISetGhost(Vec vv, PetscInt nghost, const PetscInt ghosts[])
855: {
856:   PetscBool flg;

858:   PetscFunctionBegin;
859:   PetscCall(PetscObjectTypeCompare((PetscObject)vv, VECMPI, &flg));
860:   /* if already fully existent VECMPI then basically destroy it and rebuild with ghosting */
861:   if (flg) {
862:     PetscInt     n, N;
863:     Vec_MPI     *w;
864:     PetscScalar *larray;
865:     IS           from, to;
866:     MPI_Comm     comm;

868:     PetscCall(PetscObjectGetComm((PetscObject)vv, &comm));
869:     n = vv->map->n;
870:     N = vv->map->N;
871:     PetscUseTypeMethod(vv, destroy);
872:     PetscCall(VecSetSizes(vv, n, N));
873:     PetscCall(VecCreate_MPI_Private(vv, PETSC_TRUE, nghost, NULL));
874:     w = (Vec_MPI *)(vv)->data;
875:     /* Create local representation */
876:     PetscCall(VecGetArray(vv, &larray));
877:     PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, n + nghost, larray, &w->localrep));
878:     PetscCall(VecRestoreArray(vv, &larray));

880:     /*
881:      Create scatter context for scattering (updating) ghost values
882:      */
883:     PetscCall(ISCreateGeneral(comm, nghost, ghosts, PETSC_COPY_VALUES, &from));
884:     PetscCall(ISCreateStride(PETSC_COMM_SELF, nghost, n, 1, &to));
885:     PetscCall(VecScatterCreate(vv, from, w->localrep, to, &w->localupdate));
886:     PetscCall(ISDestroy(&to));

888:     w->ghost                         = from;
889:     vv->ops->getlocaltoglobalmapping = VecGetLocalToGlobalMapping_MPI_VecGhost;
890:   } else {
891:     PetscCheck(vv->ops->create != VecCreate_MPI, PetscObjectComm((PetscObject)vv), PETSC_ERR_ARG_WRONGSTATE, "Must set local or global size before setting ghosting");
892:     PetscCheck(((PetscObject)vv)->type_name, PetscObjectComm((PetscObject)vv), PETSC_ERR_ARG_WRONGSTATE, "Must set type to VECMPI before ghosting");
893:   }
894:   PetscFunctionReturn(PETSC_SUCCESS);
895: }

897: /* ------------------------------------------------------------------------------------------*/
898: /*@C
899:   VecCreateGhostBlockWithArray - Creates a parallel vector with ghost padding on each processor;
900:   the caller allocates the array space. Indices in the ghost region are based on blocks.

902:   Collective

904:   Input Parameters:
905: + comm   - the MPI communicator to use
906: . bs     - block size
907: . n      - local vector length
908: . N      - global vector length (or `PETSC_DETERMINE` to have calculated if `n` is given)
909: . nghost - number of local ghost blocks
910: . ghosts - global indices of ghost blocks (or `NULL` if not needed), counts are by block not by index, these do not need to be in increasing order (sorted)
911: - array  - the space to store the vector values (as long as `n + nghost*bs`)

913:   Output Parameter:
914: . vv - the global vector representation (without ghost points as part of vector)

916:   Level: advanced

918:   Notes:
919:   Use `VecGhostGetLocalForm()` to access the local, ghosted representation
920:   of the vector.

922:   n is the local vector size (total local size not the number of blocks) while nghost
923:   is the number of blocks in the ghost portion, i.e. the number of elements in the ghost
924:   portion is bs*nghost

926: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreate()`, `VecGhostGetLocalForm()`, `VecGhostRestoreLocalForm()`,
927:           `VecCreateGhost()`, `VecCreateSeqWithArray()`, `VecCreateMPIWithArray()`,
928:           `VecCreateGhostWithArray()`, `VecCreateGhostBlock()`
929: @*/
930: PetscErrorCode VecCreateGhostBlockWithArray(MPI_Comm comm, PetscInt bs, PetscInt n, PetscInt N, PetscInt nghost, const PetscInt ghosts[], const PetscScalar array[], Vec *vv)
931: {
932:   Vec_MPI               *w;
933:   PetscScalar           *larray;
934:   IS                     from, to;
935:   ISLocalToGlobalMapping ltog;
936:   PetscInt               rstart, i, nb, *indices;

938:   PetscFunctionBegin;
939:   *vv = NULL;

941:   PetscCheck(n != PETSC_DECIDE, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Must set local size");
942:   PetscCheck(nghost != PETSC_DECIDE, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Must set local ghost size");
943:   PetscCheck(nghost >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Ghost length must be >= 0");
944:   PetscCheck(n % bs == 0, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Local size must be a multiple of block size");
945:   PetscCall(PetscSplitOwnership(comm, &n, &N));
946:   /* Create global representation */
947:   PetscCall(VecCreate(comm, vv));
948:   PetscCall(VecSetSizes(*vv, n, N));
949:   PetscCall(VecSetBlockSize(*vv, bs));
950:   PetscCall(VecCreate_MPI_Private(*vv, PETSC_TRUE, nghost * bs, array));
951:   w = (Vec_MPI *)(*vv)->data;
952:   /* Create local representation */
953:   PetscCall(VecGetArray(*vv, &larray));
954:   PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, bs, n + bs * nghost, larray, &w->localrep));
955:   PetscCall(VecRestoreArray(*vv, &larray));

957:   /*
958:        Create scatter context for scattering (updating) ghost values
959:   */
960:   PetscCall(ISCreateBlock(comm, bs, nghost, ghosts, PETSC_COPY_VALUES, &from));
961:   PetscCall(ISCreateStride(PETSC_COMM_SELF, bs * nghost, n, 1, &to));
962:   PetscCall(VecScatterCreate(*vv, from, w->localrep, to, &w->localupdate));
963:   PetscCall(ISDestroy(&to));
964:   PetscCall(ISDestroy(&from));

966:   /* set local to global mapping for ghosted vector */
967:   nb = n / bs;
968:   PetscCall(PetscMalloc1(nb + nghost, &indices));
969:   PetscCall(VecGetOwnershipRange(*vv, &rstart, NULL));
970:   rstart = rstart / bs;

972:   for (i = 0; i < nb; i++) indices[i] = rstart + i;
973:   for (i = 0; i < nghost; i++) indices[nb + i] = ghosts[i];

975:   PetscCall(ISLocalToGlobalMappingCreate(comm, bs, nb + nghost, indices, PETSC_OWN_POINTER, &ltog));
976:   PetscCall(VecSetLocalToGlobalMapping(*vv, ltog));
977:   PetscCall(ISLocalToGlobalMappingDestroy(&ltog));
978:   PetscFunctionReturn(PETSC_SUCCESS);
979: }

981: /*@
982:   VecCreateGhostBlock - Creates a parallel vector with ghost padding on each processor.
983:   The indicing of the ghost points is done with blocks.

985:   Collective

987:   Input Parameters:
988: + comm   - the MPI communicator to use
989: . bs     - the block size
990: . n      - local vector length
991: . N      - global vector length (or `PETSC_DETERMINE` to have calculated if `n` is given)
992: . nghost - number of local ghost blocks
993: - ghosts - global indices of ghost blocks, counts are by block, not by individual index, these do not need to be in increasing order (sorted)

995:   Output Parameter:
996: . vv - the global vector representation (without ghost points as part of vector)

998:   Level: advanced

1000:   Notes:
1001:   Use `VecGhostGetLocalForm()` to access the local, ghosted representation
1002:   of the vector.

1004:   `n` is the local vector size (total local size not the number of blocks) while `nghost`
1005:   is the number of blocks in the ghost portion, i.e. the number of elements in the ghost
1006:   portion is `bs*nghost`

1008: .seealso: [](ch_vectors), `Vec`, `VecType`, `VecCreateSeq()`, `VecCreate()`, `VecDuplicate()`, `VecDuplicateVecs()`, `VecCreateMPI()`,
1009:           `VecGhostGetLocalForm()`, `VecGhostRestoreLocalForm()`,
1010:           `VecCreateGhostWithArray()`, `VecCreateMPIWithArray()`, `VecCreateGhostBlockWithArray()`
1011: @*/
1012: PetscErrorCode VecCreateGhostBlock(MPI_Comm comm, PetscInt bs, PetscInt n, PetscInt N, PetscInt nghost, const PetscInt ghosts[], Vec *vv)
1013: {
1014:   PetscFunctionBegin;
1015:   PetscCall(VecCreateGhostBlockWithArray(comm, bs, n, N, nghost, ghosts, NULL, vv));
1016:   PetscFunctionReturn(PETSC_SUCCESS);
1017: }