Actual source code: telescope_coarsedm.c


  2: #include <petsc/private/matimpl.h>
  3: #include <petsc/private/pcimpl.h>
  4: #include <petsc/private/dmimpl.h>
  5: #include <petscksp.h>
  6: #include <petscdm.h>
  7: #include <petscdmda.h>
  8: #include <petscdmshell.h>

 10: #include "../src/ksp/pc/impls/telescope/telescope.h"

 12: static PetscBool  cited = PETSC_FALSE;
 13: static const char citation[] =
 14: "@inproceedings{MaySananRuppKnepleySmith2016,\n"
 15: "  title     = {Extreme-Scale Multigrid Components within PETSc},\n"
 16: "  author    = {Dave A. May and Patrick Sanan and Karl Rupp and Matthew G. Knepley and Barry F. Smith},\n"
 17: "  booktitle = {Proceedings of the Platform for Advanced Scientific Computing Conference},\n"
 18: "  series    = {PASC '16},\n"
 19: "  isbn      = {978-1-4503-4126-4},\n"
 20: "  location  = {Lausanne, Switzerland},\n"
 21: "  pages     = {5:1--5:12},\n"
 22: "  articleno = {5},\n"
 23: "  numpages  = {12},\n"
 24: "  url       = {https://doi.acm.org/10.1145/2929908.2929913},\n"
 25: "  doi       = {10.1145/2929908.2929913},\n"
 26: "  acmid     = {2929913},\n"
 27: "  publisher = {ACM},\n"
 28: "  address   = {New York, NY, USA},\n"
 29: "  keywords  = {GPU, HPC, agglomeration, coarse-level solver, multigrid, parallel computing, preconditioning},\n"
 30: "  year      = {2016}\n"
 31: "}\n";

 33: typedef struct {
 34:   DM              dm_fine,dm_coarse; /* these DM's should be topologically identical but use different communicators */
 35:   Mat             permutation;
 36:   Vec             xp;
 37:   PetscErrorCode  (*fp_dm_field_scatter)(DM,Vec,ScatterMode,DM,Vec);
 38:   PetscErrorCode  (*fp_dm_state_scatter)(DM,ScatterMode,DM);
 39:   void            *dmksp_context_determined;
 40:   void            *dmksp_context_user;
 41: } PC_Telescope_CoarseDMCtx;

 43: PetscErrorCode PCTelescopeSetUp_scatters_CoarseDM(PC pc,PC_Telescope sred,PC_Telescope_CoarseDMCtx *ctx)
 44: {
 46:   Vec            xred,yred,xtmp,x,xp;
 47:   VecScatter     scatter;
 48:   IS             isin;
 49:   Mat            B;
 50:   PetscInt       m,bs,st,ed;
 51:   MPI_Comm       comm;

 54:   PetscObjectGetComm((PetscObject)pc,&comm);
 55:   PCGetOperators(pc,NULL,&B);
 56:   MatCreateVecs(B,&x,NULL);
 57:   MatGetBlockSize(B,&bs);
 58:   VecDuplicate(x,&xp);
 59:   m = 0;
 60:   xred = NULL;
 61:   yred = NULL;
 62:   if (PCTelescope_isActiveRank(sred)) {
 63:     DMCreateGlobalVector(ctx->dm_coarse,&xred);
 64:     VecDuplicate(xred,&yred);
 65:     VecGetOwnershipRange(xred,&st,&ed);
 66:     ISCreateStride(comm,ed-st,st,1,&isin);
 67:     VecGetLocalSize(xred,&m);
 68:   } else {
 69:     VecGetOwnershipRange(x,&st,&ed);
 70:     ISCreateStride(comm,0,st,1,&isin);
 71:   }
 72:   ISSetBlockSize(isin,bs);
 73:   VecCreate(comm,&xtmp);
 74:   VecSetSizes(xtmp,m,PETSC_DECIDE);
 75:   VecSetBlockSize(xtmp,bs);
 76:   VecSetType(xtmp,((PetscObject)x)->type_name);
 77:   VecScatterCreate(x,isin,xtmp,NULL,&scatter);
 78:   sred->xred    = xred;
 79:   sred->yred    = yred;
 80:   sred->isin    = isin;
 81:   sred->scatter = scatter;
 82:   sred->xtmp    = xtmp;
 83:   ctx->xp       = xp;
 84:   VecDestroy(&x);
 85:   return(0);
 86: }

 88: PetscErrorCode PCTelescopeSetUp_CoarseDM(PC pc,PC_Telescope sred)
 89: {
 90:   PC_Telescope_CoarseDMCtx *ctx;
 91:   DM                       dm,dm_coarse = NULL;
 92:   MPI_Comm                 comm;
 93:   PetscBool                has_perm,has_kspcomputeoperators,using_kspcomputeoperators;
 94:   PetscErrorCode           ierr;

 97:   PetscInfo(pc,"PCTelescope: setup (CoarseDM)\n");
 98:   PetscNew(&ctx);
 99:   sred->dm_ctx = (void*)ctx;

101:   PetscObjectGetComm((PetscObject)pc,&comm);
102:   PCGetDM(pc,&dm);
103:   DMGetCoarseDM(dm,&dm_coarse);
104:   ctx->dm_fine   = dm;
105:   ctx->dm_coarse = dm_coarse;

107:   /* attach coarse dm to ksp on sub communicator */
108:   if (PCTelescope_isActiveRank(sred)) {
109:     KSPSetDM(sred->ksp,ctx->dm_coarse);
110:     if (sred->ignore_kspcomputeoperators) {
111:       KSPSetDMActive(sred->ksp,PETSC_FALSE);
112:     }
113:   }

115:   /* check if there is a method to provide a permutation */
116:   has_perm = PETSC_FALSE;
117:   has_kspcomputeoperators = PETSC_FALSE;
118:   using_kspcomputeoperators = PETSC_FALSE;

120:   /* if no permutation is provided, we must rely on KSPSetComputeOperators */
121:   {
122:     PetscErrorCode (*dmfine_kspfunc)(KSP,Mat,Mat,void*) = NULL;
123:     void           *dmfine_kspctx = NULL,*dmcoarse_kspctx = NULL;
124:     void           *dmfine_appctx = NULL,*dmcoarse_appctx = NULL;
125:     void           *dmfine_shellctx = NULL,*dmcoarse_shellctx = NULL;

127:     DMKSPGetComputeOperators(dm,&dmfine_kspfunc,&dmfine_kspctx);
128:     if (dmfine_kspfunc) { has_kspcomputeoperators = PETSC_TRUE; }

130:     DMGetApplicationContext(ctx->dm_fine,&dmfine_appctx);
131:     DMShellGetContext(ctx->dm_fine,&dmfine_shellctx);

133:     /* need to define dmcoarse_kspctx */
134:     if (dmfine_kspfunc && !sred->ignore_kspcomputeoperators) {

136:       PetscInfo(pc,"PCTelescope: KSPSetComputeOperators fetched from parent DM\n");
137:       if (PCTelescope_isActiveRank(sred)) {
138:         DMGetApplicationContext(ctx->dm_coarse,&dmcoarse_appctx);
139:         DMShellGetContext(ctx->dm_coarse,&dmcoarse_shellctx);
140:       }

142:       /* Assume that if the fine operator didn't require any context, neither will the coarse */
143:       if (!dmfine_kspctx) {
144:         dmcoarse_kspctx = NULL;
145:         PetscInfo(pc,"PCTelescope: KSPSetComputeOperators using NULL context\n");
146:       } else {

148:         PetscInfo(pc,"PCTelescope: KSPSetComputeOperators detected non-NULL context from parent DM \n");
149:         if (PCTelescope_isActiveRank(sred)) {

151:           if (dmfine_kspctx == dmfine_appctx) {
152:             dmcoarse_kspctx = dmcoarse_appctx;
153:             PetscInfo(pc,"PCTelescope: KSPSetComputeOperators using context from DM->ApplicationContext\n");
154:             if (!dmcoarse_kspctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Non NULL dmfine->kspctx == dmfine->appctx. NULL dmcoarse->appctx found. Likely this is an error");
155:           } else if (dmfine_kspctx == dmfine_shellctx) {
156:             dmcoarse_kspctx = dmcoarse_shellctx;
157:             PetscInfo(pc,"PCTelescope: KSPSetComputeOperators using context from DMShell->Context\n");
158:             if (!dmcoarse_kspctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Non NULL dmfine->kspctx == dmfine.shell->ctx. NULL dmcoarse.shell->ctx found. Likely this is an error");
159:           }
160:           ctx->dmksp_context_determined = dmcoarse_kspctx;

162:           /* look for user provided method to fetch the context */
163:           {
164:             PetscErrorCode (*fp_get_coarsedm_context)(DM,void**) = NULL;
165:             void *dmcoarse_context_user = NULL;
166:             char dmcoarse_method[PETSC_MAX_PATH_LEN];

168:             PetscSNPrintf(dmcoarse_method,sizeof(dmcoarse_method),"PCTelescopeGetCoarseDMKSPContext");
169:             PetscObjectQueryFunction((PetscObject)ctx->dm_coarse,dmcoarse_method,&fp_get_coarsedm_context);
170:             if (fp_get_coarsedm_context) {
171:               PetscInfo(pc,"PCTelescope: Found composed method PCTelescopeGetCoarseDMKSPContext from coarse DM\n");
172:               fp_get_coarsedm_context(ctx->dm_coarse,&dmcoarse_context_user);
173:               ctx->dmksp_context_user = dmcoarse_context_user;
174:               dmcoarse_kspctx = dmcoarse_context_user;
175:             } else {
176:               PetscInfo(pc,"PCTelescope: Failed to find composed method PCTelescopeGetCoarseDMKSPContext from coarse DM\n");
177:             }
178:           }

180:           if (!dmcoarse_kspctx) {
181:             PetscInfo(pc,"PCTelescope: KSPSetComputeOperators failed to determine the context to use on sub-communicator\n");
182:             SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Cannot determine which context with use for KSPSetComputeOperators() on sub-communicator");
183:           }
184:         }
185:       }
186:     }

188:     if (dmfine_kspfunc && !sred->ignore_kspcomputeoperators) {
189:       using_kspcomputeoperators = PETSC_TRUE;

191:       if (PCTelescope_isActiveRank(sred)) {
192:         /* sub ksp inherits dmksp_func and context provided by user */
193:         KSPSetComputeOperators(sred->ksp,dmfine_kspfunc,dmcoarse_kspctx);
194:         /*PetscObjectCopyFortranFunctionPointers((PetscObject)dm,(PetscObject)ctx->dmrepart);*/
195:         KSPSetDMActive(sred->ksp,PETSC_TRUE);
196:       }
197:     }
198:   }

200:   if (!has_perm && has_kspcomputeoperators && !using_kspcomputeoperators) SETERRQ(comm,PETSC_ERR_SUP,"No method to permute an operator was found on the parent DM. A method for KSPSetComputeOperators() was provided but it was requested to be ignored. Telescope setup cannot proceed");
201:   if (!has_perm && !has_kspcomputeoperators) SETERRQ(comm,PETSC_ERR_SUP,"No method to permute an operator was found on the parent DM. No method for KSPSetComputeOperators() was provided. Telescope setup cannot proceed");

203:   {
204:     char dmfine_method[PETSC_MAX_PATH_LEN];

206:     PetscSNPrintf(dmfine_method,sizeof(dmfine_method),"PCTelescopeFieldScatter");
207:     PetscObjectQueryFunction((PetscObject)ctx->dm_fine,dmfine_method,&ctx->fp_dm_field_scatter);

209:     PetscSNPrintf(dmfine_method,sizeof(dmfine_method),"PCTelescopeStateScatter");
210:     PetscObjectQueryFunction((PetscObject)ctx->dm_fine,dmfine_method,&ctx->fp_dm_state_scatter);
211:   }

213:   if (ctx->fp_dm_state_scatter) {
214:     PetscInfo(pc,"PCTelescope: Found composed method PCTelescopeStateScatter from parent DM\n");
215:   } else {
216:     PetscInfo(pc,"PCTelescope: Failed to find composed method PCTelescopeStateScatter from parent DM\n");
217:   }

219:   if (ctx->fp_dm_field_scatter) {
220:     PetscInfo(pc,"PCTelescope: Found composed method PCTelescopeFieldScatter from parent DM\n");
221:   } else {
222:     PetscInfo(pc,"PCTelescope: Failed to find composed method PCTelescopeFieldScatter from parent DM\n");
223:     SETERRQ(comm,PETSC_ERR_SUP,"No method to scatter fields between the parent DM and coarse DM was found. Must call PetscObjectComposeFunction() with the parent DM. Telescope setup cannot proceed");
224:   }

226:   /*PCTelescopeSetUp_permutation_CoarseDM(pc,sred,ctx);*/
227:   PCTelescopeSetUp_scatters_CoarseDM(pc,sred,ctx);
228:   return(0);
229: }

231: PetscErrorCode PCApply_Telescope_CoarseDM(PC pc,Vec x,Vec y)
232: {
233:   PC_Telescope             sred = (PC_Telescope)pc->data;
234:   PetscErrorCode           ierr;
235:   Vec                      xred,yred;
236:   PC_Telescope_CoarseDMCtx *ctx;

239:   ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx;
240:   xred = sred->xred;
241:   yred = sred->yred;

243:   PetscCitationsRegister(citation,&cited);

245:   if (ctx->fp_dm_state_scatter) {
246:     ctx->fp_dm_state_scatter(ctx->dm_fine,SCATTER_FORWARD,ctx->dm_coarse);
247:   }

249:   ctx->fp_dm_field_scatter(ctx->dm_fine,x,SCATTER_FORWARD,ctx->dm_coarse,xred);

251:   /* solve */
252:   if (PCTelescope_isActiveRank(sred)) {
253:     KSPSolve(sred->ksp,xred,yred);
254:   }

256:   ctx->fp_dm_field_scatter(ctx->dm_fine,y,SCATTER_REVERSE,ctx->dm_coarse,yred);
257:   return(0);
258: }

260: PetscErrorCode PCTelescopeSubNullSpaceCreate_CoarseDM(PC pc,PC_Telescope sred,MatNullSpace nullspace,MatNullSpace *sub_nullspace)
261: {
262:   PetscErrorCode           ierr;
263:   PetscBool                has_const;
264:   PetscInt                 k,n = 0;
265:   const Vec                *vecs;
266:   Vec                      *sub_vecs = NULL;
267:   MPI_Comm                 subcomm;
268:   PC_Telescope_CoarseDMCtx *ctx;

271:   ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx;
272:   subcomm = sred->subcomm;
273:   MatNullSpaceGetVecs(nullspace,&has_const,&n,&vecs);

275:   if (PCTelescope_isActiveRank(sred)) {
276:     /* create new vectors */
277:     if (n) {
278:       VecDuplicateVecs(sred->xred,n,&sub_vecs);
279:     }
280:   }

282:   /* copy entries */
283:   for (k=0; k<n; k++) {
284:     ctx->fp_dm_field_scatter(ctx->dm_fine,vecs[k],SCATTER_FORWARD,ctx->dm_coarse,sub_vecs[k]);
285:   }

287:   if (PCTelescope_isActiveRank(sred)) {
288:     /* create new (near) nullspace for redundant object */
289:     MatNullSpaceCreate(subcomm,has_const,n,sub_vecs,sub_nullspace);
290:     VecDestroyVecs(n,&sub_vecs);
291:   }
292:   return(0);
293: }

295: PetscErrorCode PCTelescopeMatNullSpaceCreate_CoarseDM(PC pc,PC_Telescope sred,Mat sub_mat)
296: {
297:   PetscErrorCode           ierr;
298:   Mat                      B;
299:   PC_Telescope_CoarseDMCtx *ctx;

302:   ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx;
303:   PCGetOperators(pc,NULL,&B);
304:   {
305:     MatNullSpace nullspace,sub_nullspace;
306:     MatGetNullSpace(B,&nullspace);
307:     if (nullspace) {
308:       PetscInfo(pc,"PCTelescope: generating nullspace (CoarseDM)\n");
309:       PCTelescopeSubNullSpaceCreate_CoarseDM(pc,sred,nullspace,&sub_nullspace);

311:       /* attach any user nullspace removal methods and contexts */
312:       if (PCTelescope_isActiveRank(sred)) {
313:         void *context = NULL;
314:         if (nullspace->remove && !nullspace->rmctx) {
315:           MatNullSpaceSetFunction(sub_nullspace,nullspace->remove,context);
316:         } else if (nullspace->remove && nullspace->rmctx) {
317:           char           dmcoarse_method[PETSC_MAX_PATH_LEN];
318:           PetscErrorCode (*fp_get_coarsedm_context)(DM,void**) = NULL;

320:           PetscSNPrintf(dmcoarse_method,sizeof(dmcoarse_method),"PCTelescopeGetCoarseDMNullSpaceUserContext");
321:           PetscObjectQueryFunction((PetscObject)ctx->dm_coarse,dmcoarse_method,&fp_get_coarsedm_context);
322:           if (!context) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"Propagation of user null-space removal method with non-NULL context requires the coarse DM be composed with a function named \"%s\"",dmcoarse_method);
323:           MatNullSpaceSetFunction(sub_nullspace,nullspace->remove,context);
324:         }
325:       }

327:       if (PCTelescope_isActiveRank(sred)) {
328:         MatSetNullSpace(sub_mat,sub_nullspace);
329:         MatNullSpaceDestroy(&sub_nullspace);
330:       }
331:     }
332:   }
333:   {
334:     MatNullSpace nearnullspace,sub_nearnullspace;
335:     MatGetNearNullSpace(B,&nearnullspace);
336:     if (nearnullspace) {
337:       PetscInfo(pc,"PCTelescope: generating near nullspace (CoarseDM)\n");
338:       PCTelescopeSubNullSpaceCreate_CoarseDM(pc,sred,nearnullspace,&sub_nearnullspace);

340:       /* attach any user nullspace removal methods and contexts */
341:       if (PCTelescope_isActiveRank(sred)) {
342:         void *context = NULL;
343:         if (nearnullspace->remove && !nearnullspace->rmctx) {
344:           MatNullSpaceSetFunction(sub_nearnullspace,nearnullspace->remove,context);
345:         } else if (nearnullspace->remove && nearnullspace->rmctx) {
346:           char           dmcoarse_method[PETSC_MAX_PATH_LEN];
347:           PetscErrorCode (*fp_get_coarsedm_context)(DM,void**) = NULL;

349:           PetscSNPrintf(dmcoarse_method,sizeof(dmcoarse_method),"PCTelescopeGetCoarseDMNearNullSpaceUserContext");
350:           PetscObjectQueryFunction((PetscObject)ctx->dm_coarse,dmcoarse_method,&fp_get_coarsedm_context);
351:           if (!context) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"Propagation of user near null-space removal method with non-NULL context requires the coarse DM be composed with a function named \"%s\"",dmcoarse_method);
352:           MatNullSpaceSetFunction(sub_nearnullspace,nearnullspace->remove,context);
353:         }
354:       }

356:       if (PCTelescope_isActiveRank(sred)) {
357:         MatSetNearNullSpace(sub_mat,sub_nearnullspace);
358:         MatNullSpaceDestroy(&sub_nearnullspace);
359:       }
360:     }
361:   }
362:   return(0);
363: }

365: PetscErrorCode PCReset_Telescope_CoarseDM(PC pc)
366: {
367:   PetscErrorCode           ierr;
368:   PC_Telescope             sred = (PC_Telescope)pc->data;
369:   PC_Telescope_CoarseDMCtx *ctx;

372:   ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx;
373:   ctx->dm_fine = NULL; /* since I did not increment the ref counter we set these to NULL */
374:   ctx->dm_coarse = NULL; /* since I did not increment the ref counter we set these to NULL */
375:   ctx->permutation = NULL; /* this will be fetched from the dm so no need to call destroy */
376:   VecDestroy(&ctx->xp);
377:   ctx->fp_dm_field_scatter = NULL;
378:   ctx->fp_dm_state_scatter = NULL;
379:   ctx->dmksp_context_determined = NULL;
380:   ctx->dmksp_context_user = NULL;
381:   return(0);
382: }

384: PetscErrorCode PCApplyRichardson_Telescope_CoarseDM(PC pc,Vec x,Vec y,Vec w,PetscReal rtol,PetscReal abstol,PetscReal dtol,PetscInt its,PetscBool zeroguess,PetscInt *outits,PCRichardsonConvergedReason *reason)
385: {
386:   PC_Telescope             sred = (PC_Telescope)pc->data;
387:   PetscErrorCode           ierr;
388:   Vec                      yred = NULL;
389:   PetscBool                default_init_guess_value = PETSC_FALSE;
390:   PC_Telescope_CoarseDMCtx *ctx;

393:   ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx;
394:   yred = sred->yred;

396:   if (its > 1) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PCApplyRichardson_Telescope_CoarseDM only supports max_it = 1");
397:   *reason = (PCRichardsonConvergedReason)0;

399:   if (!zeroguess) {
400:     PetscInfo(pc,"PCTelescopeCoarseDM: Scattering y for non-zero-initial guess\n");

402:     ctx->fp_dm_field_scatter(ctx->dm_fine,y,SCATTER_FORWARD,ctx->dm_coarse,yred);
403:   }

405:   if (PCTelescope_isActiveRank(sred)) {
406:     KSPGetInitialGuessNonzero(sred->ksp,&default_init_guess_value);
407:     if (!zeroguess) {KSPSetInitialGuessNonzero(sred->ksp,PETSC_TRUE);}
408:   }

410:   PCApply_Telescope_CoarseDM(pc,x,y);

412:   if (PCTelescope_isActiveRank(sred)) {
413:     KSPSetInitialGuessNonzero(sred->ksp,default_init_guess_value);
414:   }

416:   if (!*reason) *reason = PCRICHARDSON_CONVERGED_ITS;
417:   *outits = 1;
418:   return(0);
419: }