1 2 #include <petsc/private/matimpl.h> 3 #include <petsc/private/pcimpl.h> 4 #include <petsc/private/dmimpl.h> 5 #include <petscksp.h> /*I "petscksp.h" I*/ 6 #include <petscdm.h> 7 #include <petscdmda.h> 8 #include <petscdmshell.h> 9 10 #include "../src/ksp/pc/impls/telescope/telescope.h" 11 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"; 32 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; 42 43 44 PetscErrorCode PCTelescopeSetUp_scatters_CoarseDM(PC pc,PC_Telescope sred,PC_Telescope_CoarseDMCtx *ctx) 45 { 46 PetscErrorCode ierr; 47 Vec xred,yred,xtmp,x,xp; 48 VecScatter scatter; 49 IS isin; 50 Mat B; 51 PetscInt m,bs,st,ed; 52 MPI_Comm comm; 53 54 PetscFunctionBegin; 55 ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr); 56 ierr = PCGetOperators(pc,NULL,&B);CHKERRQ(ierr); 57 ierr = MatCreateVecs(B,&x,NULL);CHKERRQ(ierr); 58 ierr = MatGetBlockSize(B,&bs);CHKERRQ(ierr); 59 ierr = VecDuplicate(x,&xp);CHKERRQ(ierr); 60 m = 0; 61 xred = NULL; 62 yred = NULL; 63 if (PCTelescope_isActiveRank(sred)) { 64 ierr = DMCreateGlobalVector(ctx->dm_coarse,&xred);CHKERRQ(ierr); 65 ierr = VecDuplicate(xred,&yred);CHKERRQ(ierr); 66 ierr = VecGetOwnershipRange(xred,&st,&ed);CHKERRQ(ierr); 67 ierr = ISCreateStride(comm,ed-st,st,1,&isin);CHKERRQ(ierr); 68 ierr = VecGetLocalSize(xred,&m);CHKERRQ(ierr); 69 } else { 70 ierr = VecGetOwnershipRange(x,&st,&ed);CHKERRQ(ierr); 71 ierr = ISCreateStride(comm,0,st,1,&isin);CHKERRQ(ierr); 72 } 73 ierr = ISSetBlockSize(isin,bs);CHKERRQ(ierr); 74 ierr = VecCreate(comm,&xtmp);CHKERRQ(ierr); 75 ierr = VecSetSizes(xtmp,m,PETSC_DECIDE);CHKERRQ(ierr); 76 ierr = VecSetBlockSize(xtmp,bs);CHKERRQ(ierr); 77 ierr = VecSetType(xtmp,((PetscObject)x)->type_name);CHKERRQ(ierr); 78 ierr = VecScatterCreate(x,isin,xtmp,NULL,&scatter);CHKERRQ(ierr); 79 sred->xred = xred; 80 sred->yred = yred; 81 sred->isin = isin; 82 sred->scatter = scatter; 83 sred->xtmp = xtmp; 84 ctx->xp = xp; 85 ierr = VecDestroy(&x);CHKERRQ(ierr); 86 PetscFunctionReturn(0); 87 } 88 89 PetscErrorCode PCTelescopeSetUp_CoarseDM(PC pc,PC_Telescope sred) 90 { 91 PC_Telescope_CoarseDMCtx *ctx; 92 DM dm,dm_coarse = NULL; 93 MPI_Comm comm; 94 PetscBool has_perm,has_kspcomputeoperators,using_kspcomputeoperators; 95 PetscErrorCode ierr; 96 97 PetscFunctionBegin; 98 ierr = PetscInfo(pc,"PCTelescope: setup (CoarseDM)\n");CHKERRQ(ierr); 99 ierr = PetscNew(&ctx);CHKERRQ(ierr); 100 sred->dm_ctx = (void*)ctx; 101 102 ierr = PetscObjectGetComm((PetscObject)pc,&comm);CHKERRQ(ierr); 103 ierr = PCGetDM(pc,&dm);CHKERRQ(ierr); 104 ierr = DMGetCoarseDM(dm,&dm_coarse);CHKERRQ(ierr); 105 ctx->dm_fine = dm; 106 ctx->dm_coarse = dm_coarse; 107 108 /* attach coarse dm to ksp on sub communicator */ 109 if (PCTelescope_isActiveRank(sred)) { 110 ierr = KSPSetDM(sred->ksp,ctx->dm_coarse);CHKERRQ(ierr); 111 if (sred->ignore_kspcomputeoperators) { 112 ierr = KSPSetDMActive(sred->ksp,PETSC_FALSE);CHKERRQ(ierr); 113 } 114 } 115 116 /* check if there is a method to provide a permutation */ 117 has_perm = PETSC_FALSE; 118 has_kspcomputeoperators = PETSC_FALSE; 119 using_kspcomputeoperators = PETSC_FALSE; 120 121 /* if no permutation is provided, we must rely on KSPSetComputeOperators */ 122 { 123 PetscErrorCode (*dmfine_kspfunc)(KSP,Mat,Mat,void*) = NULL; 124 void *dmfine_kspctx = NULL,*dmcoarse_kspctx = NULL; 125 void *dmfine_appctx = NULL,*dmcoarse_appctx = NULL; 126 void *dmfine_shellctx = NULL,*dmcoarse_shellctx = NULL; 127 128 ierr = DMKSPGetComputeOperators(dm,&dmfine_kspfunc,&dmfine_kspctx);CHKERRQ(ierr); 129 if (dmfine_kspfunc) { has_kspcomputeoperators = PETSC_TRUE; } 130 131 ierr = DMGetApplicationContext(ctx->dm_fine,&dmfine_appctx);CHKERRQ(ierr); 132 ierr = DMShellGetContext(ctx->dm_fine,&dmfine_shellctx);CHKERRQ(ierr); 133 134 /* need to define dmcoarse_kspctx */ 135 if (dmfine_kspfunc && !sred->ignore_kspcomputeoperators) { 136 137 ierr = PetscInfo(pc,"PCTelescope: KSPSetComputeOperators fetched from parent DM\n");CHKERRQ(ierr); 138 if (PCTelescope_isActiveRank(sred)) { 139 ierr = DMGetApplicationContext(ctx->dm_coarse,&dmcoarse_appctx);CHKERRQ(ierr); 140 ierr = DMShellGetContext(ctx->dm_coarse,&dmcoarse_shellctx);CHKERRQ(ierr); 141 } 142 143 /* Assume that if the fine operator didn't require any context, neither will the coarse */ 144 if (!dmfine_kspctx) { 145 dmcoarse_kspctx = NULL; 146 ierr = PetscInfo(pc,"PCTelescope: KSPSetComputeOperators using NULL context\n");CHKERRQ(ierr); 147 } else { 148 149 ierr = PetscInfo(pc,"PCTelescope: KSPSetComputeOperators detected non-NULL context from parent DM \n");CHKERRQ(ierr); 150 if (PCTelescope_isActiveRank(sred)) { 151 152 if (dmfine_kspctx == dmfine_appctx) { 153 dmcoarse_kspctx = dmcoarse_appctx; 154 ierr = PetscInfo(pc,"PCTelescope: KSPSetComputeOperators using context from DM->ApplicationContext\n");CHKERRQ(ierr); 155 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"); 156 } else if (dmfine_kspctx == dmfine_shellctx) { 157 dmcoarse_kspctx = dmcoarse_shellctx; 158 ierr = PetscInfo(pc,"PCTelescope: KSPSetComputeOperators using context from DMShell->Context\n");CHKERRQ(ierr); 159 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"); 160 } 161 ctx->dmksp_context_determined = dmcoarse_kspctx; 162 163 /* look for user provided method to fetch the context */ 164 { 165 PetscErrorCode (*fp_get_coarsedm_context)(DM,void**) = NULL; 166 void *dmcoarse_context_user = NULL; 167 char dmcoarse_method[PETSC_MAX_PATH_LEN]; 168 169 ierr = PetscSNPrintf(dmcoarse_method,sizeof(dmcoarse_method),"PCTelescopeGetCoarseDMKSPContext");CHKERRQ(ierr); 170 ierr = PetscObjectQueryFunction((PetscObject)ctx->dm_coarse,dmcoarse_method,&fp_get_coarsedm_context);CHKERRQ(ierr); 171 if (fp_get_coarsedm_context) { 172 ierr = PetscInfo(pc,"PCTelescope: Found composed method PCTelescopeGetCoarseDMKSPContext from coarse DM\n");CHKERRQ(ierr); 173 ierr = fp_get_coarsedm_context(ctx->dm_coarse,&dmcoarse_context_user);CHKERRQ(ierr); 174 ctx->dmksp_context_user = dmcoarse_context_user; 175 dmcoarse_kspctx = dmcoarse_context_user; 176 } else { 177 ierr = PetscInfo(pc,"PCTelescope: Failed to find composed method PCTelescopeGetCoarseDMKSPContext from coarse DM\n");CHKERRQ(ierr); 178 } 179 } 180 181 if (!dmcoarse_kspctx) { 182 ierr = PetscInfo(pc,"PCTelescope: KSPSetComputeOperators failed to determine the context to use on sub-communicator\n");CHKERRQ(ierr); 183 SETERRQ(PETSC_COMM_SELF,PETSC_ERR_USER,"Cannot determine which context with use for KSPSetComputeOperators() on sub-communicator"); 184 } 185 } 186 } 187 } 188 189 if (dmfine_kspfunc && !sred->ignore_kspcomputeoperators) { 190 using_kspcomputeoperators = PETSC_TRUE; 191 192 if (PCTelescope_isActiveRank(sred)) { 193 /* sub ksp inherits dmksp_func and context provided by user */ 194 ierr = KSPSetComputeOperators(sred->ksp,dmfine_kspfunc,dmcoarse_kspctx);CHKERRQ(ierr); 195 /*ierr = PetscObjectCopyFortranFunctionPointers((PetscObject)dm,(PetscObject)ctx->dmrepart);CHKERRQ(ierr);*/ 196 ierr = KSPSetDMActive(sred->ksp,PETSC_TRUE);CHKERRQ(ierr); 197 } 198 } 199 } 200 201 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"); 202 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 { 205 char dmfine_method[PETSC_MAX_PATH_LEN]; 206 207 ierr = PetscSNPrintf(dmfine_method,sizeof(dmfine_method),"PCTelescopeFieldScatter");CHKERRQ(ierr); 208 ierr = PetscObjectQueryFunction((PetscObject)ctx->dm_fine,dmfine_method,&ctx->fp_dm_field_scatter);CHKERRQ(ierr); 209 210 ierr = PetscSNPrintf(dmfine_method,sizeof(dmfine_method),"PCTelescopeStateScatter");CHKERRQ(ierr); 211 ierr = PetscObjectQueryFunction((PetscObject)ctx->dm_fine,dmfine_method,&ctx->fp_dm_state_scatter);CHKERRQ(ierr); 212 } 213 214 if (ctx->fp_dm_state_scatter) { 215 ierr = PetscInfo(pc,"PCTelescope: Found composed method PCTelescopeStateScatter from parent DM\n");CHKERRQ(ierr); 216 } else { 217 ierr = PetscInfo(pc,"PCTelescope: Failed to find composed method PCTelescopeStateScatter from parent DM\n");CHKERRQ(ierr); 218 } 219 220 if (ctx->fp_dm_field_scatter) { 221 ierr = PetscInfo(pc,"PCTelescope: Found composed method PCTelescopeFieldScatter from parent DM\n");CHKERRQ(ierr); 222 } else { 223 ierr = PetscInfo(pc,"PCTelescope: Failed to find composed method PCTelescopeFieldScatter from parent DM\n");CHKERRQ(ierr); 224 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"); 225 } 226 227 /*ierr = PCTelescopeSetUp_permutation_CoarseDM(pc,sred,ctx);CHKERRQ(ierr);*/ 228 ierr = PCTelescopeSetUp_scatters_CoarseDM(pc,sred,ctx);CHKERRQ(ierr); 229 PetscFunctionReturn(0); 230 } 231 232 PetscErrorCode PCApply_Telescope_CoarseDM(PC pc,Vec x,Vec y) 233 { 234 PC_Telescope sred = (PC_Telescope)pc->data; 235 PetscErrorCode ierr; 236 Vec xred,yred; 237 PC_Telescope_CoarseDMCtx *ctx; 238 239 PetscFunctionBegin; 240 ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx; 241 xred = sred->xred; 242 yred = sred->yred; 243 244 ierr = PetscCitationsRegister(citation,&cited);CHKERRQ(ierr); 245 246 if (ctx->fp_dm_state_scatter) { 247 ierr = ctx->fp_dm_state_scatter(ctx->dm_fine,SCATTER_FORWARD,ctx->dm_coarse);CHKERRQ(ierr); 248 } 249 250 ierr = ctx->fp_dm_field_scatter(ctx->dm_fine,x,SCATTER_FORWARD,ctx->dm_coarse,xred);CHKERRQ(ierr); 251 252 /* solve */ 253 if (PCTelescope_isActiveRank(sred)) { 254 ierr = KSPSolve(sred->ksp,xred,yred);CHKERRQ(ierr); 255 } 256 257 ierr = ctx->fp_dm_field_scatter(ctx->dm_fine,y,SCATTER_REVERSE,ctx->dm_coarse,yred);CHKERRQ(ierr); 258 PetscFunctionReturn(0); 259 } 260 261 PetscErrorCode PCTelescopeSubNullSpaceCreate_CoarseDM(PC pc,PC_Telescope sred,MatNullSpace nullspace,MatNullSpace *sub_nullspace) 262 { 263 PetscErrorCode ierr; 264 PetscBool has_const; 265 PetscInt k,n = 0; 266 const Vec *vecs; 267 Vec *sub_vecs = NULL; 268 MPI_Comm subcomm; 269 PC_Telescope_CoarseDMCtx *ctx; 270 271 PetscFunctionBegin; 272 ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx; 273 subcomm = sred->subcomm; 274 ierr = MatNullSpaceGetVecs(nullspace,&has_const,&n,&vecs);CHKERRQ(ierr); 275 276 if (PCTelescope_isActiveRank(sred)) { 277 /* create new vectors */ 278 if (n) { 279 ierr = VecDuplicateVecs(sred->xred,n,&sub_vecs);CHKERRQ(ierr); 280 } 281 } 282 283 /* copy entries */ 284 for (k=0; k<n; k++) { 285 ierr = ctx->fp_dm_field_scatter(ctx->dm_fine,vecs[k],SCATTER_FORWARD,ctx->dm_coarse,sub_vecs[k]);CHKERRQ(ierr); 286 } 287 288 if (PCTelescope_isActiveRank(sred)) { 289 /* create new (near) nullspace for redundant object */ 290 ierr = MatNullSpaceCreate(subcomm,has_const,n,sub_vecs,sub_nullspace);CHKERRQ(ierr); 291 ierr = VecDestroyVecs(n,&sub_vecs);CHKERRQ(ierr); 292 } 293 PetscFunctionReturn(0); 294 } 295 296 PetscErrorCode PCTelescopeMatNullSpaceCreate_CoarseDM(PC pc,PC_Telescope sred,Mat sub_mat) 297 { 298 PetscErrorCode ierr; 299 Mat B; 300 PC_Telescope_CoarseDMCtx *ctx; 301 302 PetscFunctionBegin; 303 ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx; 304 ierr = PCGetOperators(pc,NULL,&B);CHKERRQ(ierr); 305 { 306 MatNullSpace nullspace,sub_nullspace; 307 ierr = MatGetNullSpace(B,&nullspace);CHKERRQ(ierr); 308 if (nullspace) { 309 ierr = PetscInfo(pc,"PCTelescope: generating nullspace (CoarseDM)\n");CHKERRQ(ierr); 310 ierr = PCTelescopeSubNullSpaceCreate_CoarseDM(pc,sred,nullspace,&sub_nullspace);CHKERRQ(ierr); 311 312 /* attach any user nullspace removal methods and contexts */ 313 if (PCTelescope_isActiveRank(sred)) { 314 void *context = NULL; 315 if (nullspace->remove && !nullspace->rmctx){ 316 ierr = MatNullSpaceSetFunction(sub_nullspace,nullspace->remove,context);CHKERRQ(ierr); 317 } else if (nullspace->remove && nullspace->rmctx) { 318 char dmcoarse_method[PETSC_MAX_PATH_LEN]; 319 PetscErrorCode (*fp_get_coarsedm_context)(DM,void**) = NULL; 320 321 ierr = PetscSNPrintf(dmcoarse_method,sizeof(dmcoarse_method),"PCTelescopeGetCoarseDMNullSpaceUserContext");CHKERRQ(ierr); 322 ierr = PetscObjectQueryFunction((PetscObject)ctx->dm_coarse,dmcoarse_method,&fp_get_coarsedm_context);CHKERRQ(ierr); 323 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); 324 ierr = MatNullSpaceSetFunction(sub_nullspace,nullspace->remove,context);CHKERRQ(ierr); 325 } 326 } 327 328 if (PCTelescope_isActiveRank(sred)) { 329 ierr = MatSetNullSpace(sub_mat,sub_nullspace);CHKERRQ(ierr); 330 ierr = MatNullSpaceDestroy(&sub_nullspace);CHKERRQ(ierr); 331 } 332 } 333 } 334 { 335 MatNullSpace nearnullspace,sub_nearnullspace; 336 ierr = MatGetNearNullSpace(B,&nearnullspace);CHKERRQ(ierr); 337 if (nearnullspace) { 338 ierr = PetscInfo(pc,"PCTelescope: generating near nullspace (CoarseDM)\n");CHKERRQ(ierr); 339 ierr = PCTelescopeSubNullSpaceCreate_CoarseDM(pc,sred,nearnullspace,&sub_nearnullspace);CHKERRQ(ierr); 340 341 /* attach any user nullspace removal methods and contexts */ 342 if (PCTelescope_isActiveRank(sred)) { 343 void *context = NULL; 344 if (nearnullspace->remove && !nearnullspace->rmctx){ 345 ierr = MatNullSpaceSetFunction(sub_nearnullspace,nearnullspace->remove,context);CHKERRQ(ierr); 346 } else if (nearnullspace->remove && nearnullspace->rmctx) { 347 char dmcoarse_method[PETSC_MAX_PATH_LEN]; 348 PetscErrorCode (*fp_get_coarsedm_context)(DM,void**) = NULL; 349 350 ierr = PetscSNPrintf(dmcoarse_method,sizeof(dmcoarse_method),"PCTelescopeGetCoarseDMNearNullSpaceUserContext");CHKERRQ(ierr); 351 ierr = PetscObjectQueryFunction((PetscObject)ctx->dm_coarse,dmcoarse_method,&fp_get_coarsedm_context);CHKERRQ(ierr); 352 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); 353 ierr = MatNullSpaceSetFunction(sub_nearnullspace,nearnullspace->remove,context);CHKERRQ(ierr); 354 } 355 } 356 357 if (PCTelescope_isActiveRank(sred)) { 358 ierr = MatSetNearNullSpace(sub_mat,sub_nearnullspace);CHKERRQ(ierr); 359 ierr = MatNullSpaceDestroy(&sub_nearnullspace);CHKERRQ(ierr); 360 } 361 } 362 } 363 PetscFunctionReturn(0); 364 } 365 366 PetscErrorCode PCReset_Telescope_CoarseDM(PC pc) 367 { 368 PetscErrorCode ierr; 369 PC_Telescope sred = (PC_Telescope)pc->data; 370 PC_Telescope_CoarseDMCtx *ctx; 371 372 PetscFunctionBegin; 373 ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx; 374 ctx->dm_fine = NULL; /* since I did not increment the ref counter we set these to NULL */ 375 ctx->dm_coarse = NULL; /* since I did not increment the ref counter we set these to NULL */ 376 ctx->permutation = NULL; /* this will be fetched from the dm so no need to call destroy */ 377 ierr = VecDestroy(&ctx->xp);CHKERRQ(ierr); 378 ctx->fp_dm_field_scatter = NULL; 379 ctx->fp_dm_state_scatter = NULL; 380 ctx->dmksp_context_determined = NULL; 381 ctx->dmksp_context_user = NULL; 382 PetscFunctionReturn(0); 383 } 384 385 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) 386 { 387 PC_Telescope sred = (PC_Telescope)pc->data; 388 PetscErrorCode ierr; 389 Vec yred = NULL; 390 PetscBool default_init_guess_value = PETSC_FALSE; 391 PC_Telescope_CoarseDMCtx *ctx; 392 393 PetscFunctionBegin; 394 ctx = (PC_Telescope_CoarseDMCtx*)sred->dm_ctx; 395 yred = sred->yred; 396 397 if (its > 1) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PCApplyRichardson_Telescope_CoarseDM only supports max_it = 1"); 398 *reason = (PCRichardsonConvergedReason)0; 399 400 if (!zeroguess) { 401 ierr = PetscInfo(pc,"PCTelescopeCoarseDM: Scattering y for non-zero-initial guess\n");CHKERRQ(ierr); 402 403 ierr = ctx->fp_dm_field_scatter(ctx->dm_fine,y,SCATTER_FORWARD,ctx->dm_coarse,yred);CHKERRQ(ierr); 404 } 405 406 if (PCTelescope_isActiveRank(sred)) { 407 ierr = KSPGetInitialGuessNonzero(sred->ksp,&default_init_guess_value);CHKERRQ(ierr); 408 if (!zeroguess) ierr = KSPSetInitialGuessNonzero(sred->ksp,PETSC_TRUE);CHKERRQ(ierr); 409 } 410 411 ierr = PCApply_Telescope_CoarseDM(pc,x,y);CHKERRQ(ierr); 412 413 if (PCTelescope_isActiveRank(sred)) { 414 ierr = KSPSetInitialGuessNonzero(sred->ksp,default_init_guess_value);CHKERRQ(ierr); 415 } 416 417 if (!*reason) *reason = PCRICHARDSON_CONVERGED_ITS; 418 *outits = 1; 419 PetscFunctionReturn(0); 420 } 421