Actual source code: scotch.c

petsc-3.8.3 2017-12-09
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  2:  #include <../src/mat/impls/adj/mpi/mpiadj.h>

  4: EXTERN_C_BEGIN
  5: #include <ptscotch.h>
  6: EXTERN_C_END

  8: typedef struct {
  9:   double     imbalance;
 10:   SCOTCH_Num strategy;
 11: } MatPartitioning_PTScotch;

 13: /*@
 14:    MatPartitioningPTScotchSetImbalance - Sets the value of the load imbalance
 15:    ratio to be used during strategy selection.

 17:    Collective on MatPartitioning

 19:    Input Parameters:
 20: +  part - the partitioning context
 21: -  imb  - the load imbalance ratio

 23:    Options Database:
 24: .  -mat_partitioning_ptscotch_imbalance <imb>

 26:    Note:
 27:    Must be in the range [0,1]. The default value is 0.01.

 29:    Level: advanced

 31: .seealso: MatPartitioningPTScotchSetStrategy(), MatPartitioningPTScotchGetImbalance()
 32: @*/
 33: PetscErrorCode MatPartitioningPTScotchSetImbalance(MatPartitioning part,PetscReal imb)
 34: {

 40:   PetscTryMethod(part,"MatPartitioningPTScotchSetImbalance_C",(MatPartitioning,PetscReal),(part,imb));
 41:   return(0);
 42: }

 44: PetscErrorCode MatPartitioningPTScotchSetImbalance_PTScotch(MatPartitioning part,PetscReal imb)
 45: {
 46:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;

 49:   if (imb==PETSC_DEFAULT) scotch->imbalance = 0.01;
 50:   else {
 51:     if (imb<0.0 || imb>1.0) SETERRQ(PetscObjectComm((PetscObject)part),PETSC_ERR_ARG_OUTOFRANGE,"Illegal value of imb. Must be in range [0,1]");
 52:     scotch->imbalance = (double)imb;
 53:   }
 54:   return(0);
 55: }

 57: /*@
 58:    MatPartitioningPTScotchGetImbalance - Gets the value of the load imbalance
 59:    ratio used during strategy selection.

 61:    Not Collective

 63:    Input Parameter:
 64: .  part - the partitioning context

 66:    Output Parameter:
 67: .  imb  - the load imbalance ratio

 69:    Level: advanced

 71: .seealso: MatPartitioningPTScotchSetImbalance()
 72: @*/
 73: PetscErrorCode MatPartitioningPTScotchGetImbalance(MatPartitioning part,PetscReal *imb)
 74: {

 80:   PetscUseMethod(part,"MatPartitioningPTScotchGetImbalance_C",(MatPartitioning,PetscReal*),(part,imb));
 81:   return(0);
 82: }

 84: PetscErrorCode MatPartitioningPTScotchGetImbalance_PTScotch(MatPartitioning part,PetscReal *imb)
 85: {
 86:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;

 89:   *imb = scotch->imbalance;
 90:   return(0);
 91: }

 93: /*@
 94:    MatPartitioningPTScotchSetStrategy - Sets the strategy to be used in PTScotch.

 96:    Collective on MatPartitioning

 98:    Input Parameters:
 99: +  part - the partitioning context
100: -  strategy - the strategy, one of
101: .vb
102:      MP_PTSCOTCH_QUALITY     - Prioritize quality over speed
103:      MP_PTSCOTCH_SPEED       - Prioritize speed over quality
104:      MP_PTSCOTCH_BALANCE     - Enforce load balance
105:      MP_PTSCOTCH_SAFETY      - Avoid methods that may fail
106:      MP_PTSCOTCH_SCALABILITY - Favor scalability as much as possible
107: .ve

109:    Options Database:
110: .  -mat_partitioning_ptscotch_strategy [quality,speed,balance,safety,scalability] - strategy

112:    Level: advanced

114:    Notes:
115:    The default is MP_SCOTCH_QUALITY. See the PTScotch documentation for more information.

117: .seealso: MatPartitioningPTScotchSetImbalance(), MatPartitioningPTScotchGetStrategy()
118: @*/
119: PetscErrorCode MatPartitioningPTScotchSetStrategy(MatPartitioning part,MPPTScotchStrategyType strategy)
120: {

126:   PetscTryMethod(part,"MatPartitioningPTScotchSetStrategy_C",(MatPartitioning,MPPTScotchStrategyType),(part,strategy));
127:   return(0);
128: }

130: PetscErrorCode MatPartitioningPTScotchSetStrategy_PTScotch(MatPartitioning part,MPPTScotchStrategyType strategy)
131: {
132:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;

135:   switch (strategy) {
136:   case MP_PTSCOTCH_QUALITY:     scotch->strategy = SCOTCH_STRATQUALITY; break;
137:   case MP_PTSCOTCH_SPEED:       scotch->strategy = SCOTCH_STRATSPEED; break;
138:   case MP_PTSCOTCH_BALANCE:     scotch->strategy = SCOTCH_STRATBALANCE; break;
139:   case MP_PTSCOTCH_SAFETY:      scotch->strategy = SCOTCH_STRATSAFETY; break;
140:   case MP_PTSCOTCH_SCALABILITY: scotch->strategy = SCOTCH_STRATSCALABILITY; break;
141:   }
142:   return(0);
143: }

145: /*@
146:    MatPartitioningPTScotchGetStrategy - Gets the strategy used in PTScotch.

148:    Not Collective

150:    Input Parameter:
151: .  part - the partitioning context

153:    Output Parameter:
154: .  strategy - the strategy

156:    Level: advanced

158: .seealso: MatPartitioningPTScotchSetStrategy()
159: @*/
160: PetscErrorCode MatPartitioningPTScotchGetStrategy(MatPartitioning part,MPPTScotchStrategyType *strategy)
161: {

167:   PetscUseMethod(part,"MatPartitioningPTScotchGetStrategy_C",(MatPartitioning,MPPTScotchStrategyType*),(part,strategy));
168:   return(0);
169: }

171: PetscErrorCode MatPartitioningPTScotchGetStrategy_PTScotch(MatPartitioning part,MPPTScotchStrategyType *strategy)
172: {
173:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;

176:   switch (scotch->strategy) {
177:   case SCOTCH_STRATQUALITY:     *strategy = MP_PTSCOTCH_QUALITY; break;
178:   case SCOTCH_STRATSPEED:       *strategy = MP_PTSCOTCH_SPEED; break;
179:   case SCOTCH_STRATBALANCE:     *strategy = MP_PTSCOTCH_BALANCE; break;
180:   case SCOTCH_STRATSAFETY:      *strategy = MP_PTSCOTCH_SAFETY; break;
181:   case SCOTCH_STRATSCALABILITY: *strategy = MP_PTSCOTCH_SCALABILITY; break;
182:   }
183:   return(0);
184: }

186: PetscErrorCode MatPartitioningView_PTScotch(MatPartitioning part, PetscViewer viewer)
187: {
188:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;
189:   PetscErrorCode           ierr;
190:   PetscBool                isascii;
191:   const char               *str=0;

194:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isascii);
195:   if (isascii) {
196:     switch (scotch->strategy) {
197:     case SCOTCH_STRATQUALITY:     str = "Prioritize quality over speed"; break;
198:     case SCOTCH_STRATSPEED:       str = "Prioritize speed over quality"; break;
199:     case SCOTCH_STRATBALANCE:     str = "Enforce load balance"; break;
200:     case SCOTCH_STRATSAFETY:      str = "Avoid methods that may fail"; break;
201:     case SCOTCH_STRATSCALABILITY: str = "Favor scalability as much as possible"; break;
202:     }
203:     PetscViewerASCIIPrintf(viewer,"  Strategy=%s\n",str);
204:     PetscViewerASCIIPrintf(viewer,"  Load imbalance ratio=%g\n",scotch->imbalance);
205:   }
206:   return(0);
207: }

209: PetscErrorCode MatPartitioningSetFromOptions_PTScotch(PetscOptionItems *PetscOptionsObject,MatPartitioning part)
210: {
211:   PetscErrorCode           ierr;
212:   PetscBool                flag;
213:   PetscReal                r;
214:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;
215:   MPPTScotchStrategyType   strat;

218:   MatPartitioningPTScotchGetStrategy(part,&strat);
219:   PetscOptionsHead(PetscOptionsObject,"PTScotch partitioning options");
220:   PetscOptionsEnum("-mat_partitioning_ptscotch_strategy","Strategy","MatPartitioningPTScotchSetStrategy",MPPTScotchStrategyTypes,(PetscEnum)strat,(PetscEnum*)&strat,&flag);
221:   if (flag) { MatPartitioningPTScotchSetStrategy(part,strat); }
222:   PetscOptionsReal("-mat_partitioning_ptscotch_imbalance","Load imbalance ratio","MatPartitioningPTScotchSetImbalance",scotch->imbalance,&r,&flag);
223:   if (flag) { MatPartitioningPTScotchSetImbalance(part,r); }
224:   PetscOptionsTail();
225:   return(0);
226: }

228: PetscErrorCode MatPartitioningApply_PTScotch(MatPartitioning part,IS *partitioning)
229: {
230:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;
231:   PetscErrorCode           ierr;
232:   PetscMPIInt              rank;
233:   Mat                      mat  = part->adj;
234:   Mat_MPIAdj               *adj = (Mat_MPIAdj*)mat->data;
235:   PetscBool                flg;
236:   PetscInt                 i,j,wgtflag=0,bs=1,nold;
237:   PetscReal                *vwgttab,deltval;
238:   SCOTCH_Num               *locals,*velotab,*veloloctab,*edloloctab,vertlocnbr,edgelocnbr,nparts=part->n;
239:   SCOTCH_Arch              archdat;
240:   SCOTCH_Dgraph            grafdat;
241:   SCOTCH_Dmapping          mappdat;
242:   SCOTCH_Strat             stradat;

245:   MPI_Comm_rank(PetscObjectComm((PetscObject)part),&rank);
246:   PetscObjectTypeCompare((PetscObject)mat,MATMPIADJ,&flg);
247:   if (!flg) {
248:     /* bs indicates if the converted matrix is "reduced" from the original and hence the
249:        resulting partition results need to be stretched to match the original matrix */
250:     nold = mat->rmap->n;
251:     MatConvert(mat,MATMPIADJ,MAT_INITIAL_MATRIX,&mat);
252:     if (mat->rmap->n > 0) bs = nold/mat->rmap->n;
253:     adj  = (Mat_MPIAdj*)mat->data;
254:   }

256:   PetscMalloc1(mat->rmap->n+1,&locals);
257:   PetscMalloc1(nparts,&vwgttab);
258:   PetscMalloc1(nparts,&velotab);
259:   for (j=0; j<nparts; j++) {
260:     if (part->part_weights) vwgttab[j] = part->part_weights[j]*nparts;
261:     else vwgttab[j] = 1.0;
262:   }
263:   for (i=0; i<nparts; i++) {
264:     deltval = PetscAbsReal(vwgttab[i]-PetscFloorReal(vwgttab[i]+0.5));
265:     if (deltval>0.01) {
266:       for (j=0; j<nparts; j++) vwgttab[j] /= deltval;
267:     }
268:   }
269:   for (i=0; i<nparts; i++) velotab[i] = (SCOTCH_Num)(vwgttab[i] + 0.5);
270:   PetscFree(vwgttab);

272:   SCOTCH_dgraphInit(&grafdat,PetscObjectComm((PetscObject)part));

274:   vertlocnbr = mat->rmap->range[rank+1] - mat->rmap->range[rank];
275:   edgelocnbr = adj->i[vertlocnbr];
276:   veloloctab = (!part->vertex_weights && !(wgtflag & 2)) ? part->vertex_weights : NULL;
277:   edloloctab = (!adj->values && !(wgtflag & 1)) ? adj->values : NULL;

279:   SCOTCH_dgraphBuild(&grafdat,0,vertlocnbr,vertlocnbr,adj->i,adj->i+1,veloloctab,
280:                             NULL,edgelocnbr,edgelocnbr,adj->j,NULL,edloloctab);

282: #if defined(PETSC_USE_DEBUG)
283:   SCOTCH_dgraphCheck(&grafdat);
284: #endif

286:   SCOTCH_archInit(&archdat);
287:   SCOTCH_stratInit(&stradat);
288:   SCOTCH_stratDgraphMapBuild(&stradat,scotch->strategy,nparts,nparts,scotch->imbalance);

290:   SCOTCH_archCmpltw(&archdat,nparts,velotab);
291:   SCOTCH_dgraphMapInit(&grafdat,&mappdat,&archdat,locals);
292:   SCOTCH_dgraphMapCompute(&grafdat,&mappdat,&stradat);

294:   SCOTCH_dgraphMapExit (&grafdat,&mappdat);
295:   SCOTCH_archExit(&archdat);
296:   SCOTCH_stratExit(&stradat);
297:   SCOTCH_dgraphExit(&grafdat);
298:   PetscFree(velotab);

300:   if (bs > 1) {
301:     PetscInt *newlocals;
302:     PetscMalloc1(bs*mat->rmap->n,&newlocals);
303:     for (i=0;i<mat->rmap->n;i++) {
304:       for (j=0;j<bs;j++) {
305:         newlocals[bs*i+j] = locals[i];
306:       }
307:     }
308:     PetscFree(locals);
309:     ISCreateGeneral(PetscObjectComm((PetscObject)part),bs*mat->rmap->n,newlocals,PETSC_OWN_POINTER,partitioning);
310:   } else {
311:     ISCreateGeneral(PetscObjectComm((PetscObject)part),mat->rmap->n,locals,PETSC_OWN_POINTER,partitioning);
312:   }

314:   if (!flg) {
315:     MatDestroy(&mat);
316:   }
317:   return(0);
318: }

320: PetscErrorCode MatPartitioningDestroy_PTScotch(MatPartitioning part)
321: {
322:   MatPartitioning_PTScotch *scotch = (MatPartitioning_PTScotch*)part->data;
323:   PetscErrorCode           ierr;

326:   PetscFree(scotch);
327:   /* clear composed functions */
328:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchSetImbalance_C",NULL);
329:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchGetImbalance_C",NULL);
330:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchSetStrategy_C",NULL);
331:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchGetStrategy_C",NULL);
332:   return(0);
333: }

335: /*MC
336:    MATPARTITIONINGPTSCOTCH - Creates a partitioning context via the external package SCOTCH.

338:    Level: beginner

340:    Notes: See http://www.labri.fr/perso/pelegrin/scotch/

342: .keywords: Partitioning, create, context

344: .seealso: MatPartitioningSetType(), MatPartitioningType
345: M*/

347: PETSC_EXTERN PetscErrorCode MatPartitioningCreate_PTScotch(MatPartitioning part)
348: {
349:   PetscErrorCode           ierr;
350:   MatPartitioning_PTScotch *scotch;

353:   PetscNewLog(part,&scotch);
354:   part->data = (void*)scotch;

356:   scotch->imbalance = 0.01;
357:   scotch->strategy  = SCOTCH_STRATQUALITY;

359:   part->ops->apply          = MatPartitioningApply_PTScotch;
360:   part->ops->view           = MatPartitioningView_PTScotch;
361:   part->ops->setfromoptions = MatPartitioningSetFromOptions_PTScotch;
362:   part->ops->destroy        = MatPartitioningDestroy_PTScotch;

364:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchSetImbalance_C",MatPartitioningPTScotchSetImbalance_PTScotch);
365:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchGetImbalance_C",MatPartitioningPTScotchGetImbalance_PTScotch);
366:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchSetStrategy_C",MatPartitioningPTScotchSetStrategy_PTScotch);
367:   PetscObjectComposeFunction((PetscObject)part,"MatPartitioningPTScotchGetStrategy_C",MatPartitioningPTScotchGetStrategy_PTScotch);
368:   return(0);
369: }