Actual source code: bjacobi.c

  1: /*
  2:    Defines a block Jacobi preconditioner.
  3: */

  5: #include <../src/ksp/pc/impls/bjacobi/bjacobi.h>

  7: static PetscErrorCode PCSetUp_BJacobi_Singleblock(PC, Mat, Mat);
  8: static PetscErrorCode PCSetUp_BJacobi_Multiblock(PC, Mat, Mat);
  9: static PetscErrorCode PCSetUp_BJacobi_Multiproc(PC);

 11: static PetscErrorCode PCSetUp_BJacobi(PC pc)
 12: {
 13:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;
 14:   Mat         mat = pc->mat, pmat = pc->pmat;
 15:   PetscBool   hasop;
 16:   PetscInt    N, M, start, i, sum, end;
 17:   PetscInt    bs, i_start = -1, i_end = -1;
 18:   PetscMPIInt rank, size;

 20:   PetscFunctionBegin;
 21:   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank));
 22:   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)pc), &size));
 23:   PetscCall(MatGetLocalSize(pc->pmat, &M, &N));
 24:   PetscCall(MatGetBlockSize(pc->pmat, &bs));

 26:   if (jac->n > 0 && jac->n < size) {
 27:     PetscCall(PCSetUp_BJacobi_Multiproc(pc));
 28:     PetscFunctionReturn(PETSC_SUCCESS);
 29:   }

 31:   /*    Determines the number of blocks assigned to each processor */
 32:   /*   local block count  given */
 33:   if (jac->n_local > 0 && jac->n < 0) {
 34:     PetscCall(MPIU_Allreduce(&jac->n_local, &jac->n, 1, MPIU_INT, MPI_SUM, PetscObjectComm((PetscObject)pc)));
 35:     if (jac->l_lens) { /* check that user set these correctly */
 36:       sum = 0;
 37:       for (i = 0; i < jac->n_local; i++) {
 38:         PetscCheck(jac->l_lens[i] / bs * bs == jac->l_lens[i], PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Mat blocksize doesn't match block Jacobi layout");
 39:         sum += jac->l_lens[i];
 40:       }
 41:       PetscCheck(sum == M, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Local lens set incorrectly");
 42:     } else {
 43:       PetscCall(PetscMalloc1(jac->n_local, &jac->l_lens));
 44:       for (i = 0; i < jac->n_local; i++) jac->l_lens[i] = bs * ((M / bs) / jac->n_local + (((M / bs) % jac->n_local) > i));
 45:     }
 46:   } else if (jac->n > 0 && jac->n_local < 0) { /* global block count given */
 47:     /* global blocks given: determine which ones are local */
 48:     if (jac->g_lens) {
 49:       /* check if the g_lens is has valid entries */
 50:       for (i = 0; i < jac->n; i++) {
 51:         PetscCheck(jac->g_lens[i], PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Zero block not allowed");
 52:         PetscCheck(jac->g_lens[i] / bs * bs == jac->g_lens[i], PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Mat blocksize doesn't match block Jacobi layout");
 53:       }
 54:       if (size == 1) {
 55:         jac->n_local = jac->n;
 56:         PetscCall(PetscMalloc1(jac->n_local, &jac->l_lens));
 57:         PetscCall(PetscArraycpy(jac->l_lens, jac->g_lens, jac->n_local));
 58:         /* check that user set these correctly */
 59:         sum = 0;
 60:         for (i = 0; i < jac->n_local; i++) sum += jac->l_lens[i];
 61:         PetscCheck(sum == M, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Global lens set incorrectly");
 62:       } else {
 63:         PetscCall(MatGetOwnershipRange(pc->pmat, &start, &end));
 64:         /* loop over blocks determining first one owned by me */
 65:         sum = 0;
 66:         for (i = 0; i < jac->n + 1; i++) {
 67:           if (sum == start) {
 68:             i_start = i;
 69:             goto start_1;
 70:           }
 71:           if (i < jac->n) sum += jac->g_lens[i];
 72:         }
 73:         SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Block sizes used in PCBJacobiSetTotalBlocks()\nare not compatible with parallel matrix layout");
 74:       start_1:
 75:         for (i = i_start; i < jac->n + 1; i++) {
 76:           if (sum == end) {
 77:             i_end = i;
 78:             goto end_1;
 79:           }
 80:           if (i < jac->n) sum += jac->g_lens[i];
 81:         }
 82:         SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Block sizes used in PCBJacobiSetTotalBlocks()\nare not compatible with parallel matrix layout");
 83:       end_1:
 84:         jac->n_local = i_end - i_start;
 85:         PetscCall(PetscMalloc1(jac->n_local, &jac->l_lens));
 86:         PetscCall(PetscArraycpy(jac->l_lens, jac->g_lens + i_start, jac->n_local));
 87:       }
 88:     } else { /* no global blocks given, determine then using default layout */
 89:       jac->n_local = jac->n / size + ((jac->n % size) > rank);
 90:       PetscCall(PetscMalloc1(jac->n_local, &jac->l_lens));
 91:       for (i = 0; i < jac->n_local; i++) {
 92:         jac->l_lens[i] = ((M / bs) / jac->n_local + (((M / bs) % jac->n_local) > i)) * bs;
 93:         PetscCheck(jac->l_lens[i], PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Too many blocks given");
 94:       }
 95:     }
 96:   } else if (jac->n < 0 && jac->n_local < 0) { /* no blocks given */
 97:     jac->n       = size;
 98:     jac->n_local = 1;
 99:     PetscCall(PetscMalloc1(1, &jac->l_lens));
100:     jac->l_lens[0] = M;
101:   } else { /* jac->n > 0 && jac->n_local > 0 */
102:     if (!jac->l_lens) {
103:       PetscCall(PetscMalloc1(jac->n_local, &jac->l_lens));
104:       for (i = 0; i < jac->n_local; i++) jac->l_lens[i] = bs * ((M / bs) / jac->n_local + (((M / bs) % jac->n_local) > i));
105:     }
106:   }
107:   PetscCheck(jac->n_local >= 1, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Number of blocks is less than number of processors");

109:   /*    Determines mat and pmat */
110:   PetscCall(MatHasOperation(pc->mat, MATOP_GET_DIAGONAL_BLOCK, &hasop));
111:   if (!hasop && size == 1) {
112:     mat  = pc->mat;
113:     pmat = pc->pmat;
114:   } else {
115:     if (pc->useAmat) {
116:       /* use block from Amat matrix, not Pmat for local MatMult() */
117:       PetscCall(MatGetDiagonalBlock(pc->mat, &mat));
118:     }
119:     if (pc->pmat != pc->mat || !pc->useAmat) {
120:       PetscCall(MatGetDiagonalBlock(pc->pmat, &pmat));
121:     } else pmat = mat;
122:   }

124:   /*
125:      Setup code depends on the number of blocks
126:   */
127:   if (jac->n_local == 1) {
128:     PetscCall(PCSetUp_BJacobi_Singleblock(pc, mat, pmat));
129:   } else {
130:     PetscCall(PCSetUp_BJacobi_Multiblock(pc, mat, pmat));
131:   }
132:   PetscFunctionReturn(PETSC_SUCCESS);
133: }

135: /* Default destroy, if it has never been setup */
136: static PetscErrorCode PCDestroy_BJacobi(PC pc)
137: {
138:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;

140:   PetscFunctionBegin;
141:   PetscCall(PetscFree(jac->g_lens));
142:   PetscCall(PetscFree(jac->l_lens));
143:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiGetSubKSP_C", NULL));
144:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiSetTotalBlocks_C", NULL));
145:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiGetTotalBlocks_C", NULL));
146:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiSetLocalBlocks_C", NULL));
147:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiGetLocalBlocks_C", NULL));
148:   PetscCall(PetscFree(pc->data));
149:   PetscFunctionReturn(PETSC_SUCCESS);
150: }

152: static PetscErrorCode PCSetFromOptions_BJacobi(PC pc, PetscOptionItems *PetscOptionsObject)
153: {
154:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;
155:   PetscInt    blocks, i;
156:   PetscBool   flg;

158:   PetscFunctionBegin;
159:   PetscOptionsHeadBegin(PetscOptionsObject, "Block Jacobi options");
160:   PetscCall(PetscOptionsInt("-pc_bjacobi_blocks", "Total number of blocks", "PCBJacobiSetTotalBlocks", jac->n, &blocks, &flg));
161:   if (flg) PetscCall(PCBJacobiSetTotalBlocks(pc, blocks, NULL));
162:   PetscCall(PetscOptionsInt("-pc_bjacobi_local_blocks", "Local number of blocks", "PCBJacobiSetLocalBlocks", jac->n_local, &blocks, &flg));
163:   if (flg) PetscCall(PCBJacobiSetLocalBlocks(pc, blocks, NULL));
164:   if (jac->ksp) {
165:     /* The sub-KSP has already been set up (e.g., PCSetUp_BJacobi_Singleblock), but KSPSetFromOptions was not called
166:      * unless we had already been called. */
167:     for (i = 0; i < jac->n_local; i++) PetscCall(KSPSetFromOptions(jac->ksp[i]));
168:   }
169:   PetscOptionsHeadEnd();
170:   PetscFunctionReturn(PETSC_SUCCESS);
171: }

173: #include <petscdraw.h>
174: static PetscErrorCode PCView_BJacobi(PC pc, PetscViewer viewer)
175: {
176:   PC_BJacobi           *jac   = (PC_BJacobi *)pc->data;
177:   PC_BJacobi_Multiproc *mpjac = (PC_BJacobi_Multiproc *)jac->data;
178:   PetscMPIInt           rank;
179:   PetscInt              i;
180:   PetscBool             iascii, isstring, isdraw;
181:   PetscViewer           sviewer;
182:   PetscViewerFormat     format;
183:   const char           *prefix;

185:   PetscFunctionBegin;
186:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
187:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
188:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
189:   if (iascii) {
190:     if (pc->useAmat) PetscCall(PetscViewerASCIIPrintf(viewer, "  using Amat local matrix, number of blocks = %" PetscInt_FMT "\n", jac->n));
191:     PetscCall(PetscViewerASCIIPrintf(viewer, "  number of blocks = %" PetscInt_FMT "\n", jac->n));
192:     PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank));
193:     PetscCall(PetscViewerGetFormat(viewer, &format));
194:     if (format != PETSC_VIEWER_ASCII_INFO_DETAIL) {
195:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Local solver information for first block is in the following KSP and PC objects on rank 0:\n"));
196:       PetscCall(PCGetOptionsPrefix(pc, &prefix));
197:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Use -%sksp_view ::ascii_info_detail to display information for all blocks\n", prefix ? prefix : ""));
198:       if (jac->ksp && !jac->psubcomm) {
199:         PetscCall(PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
200:         if (rank == 0) {
201:           PetscCall(PetscViewerASCIIPushTab(sviewer));
202:           PetscCall(KSPView(jac->ksp[0], sviewer));
203:           PetscCall(PetscViewerASCIIPopTab(sviewer));
204:         }
205:         PetscCall(PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
206:         /*  extra call needed because of the two calls to PetscViewerASCIIPushSynchronized() in PetscViewerGetSubViewer() */
207:         PetscCall(PetscViewerASCIIPopSynchronized(viewer));
208:       } else if (mpjac && jac->ksp && mpjac->psubcomm) {
209:         PetscCall(PetscViewerGetSubViewer(viewer, mpjac->psubcomm->child, &sviewer));
210:         if (!mpjac->psubcomm->color) {
211:           PetscCall(PetscViewerASCIIPushTab(sviewer));
212:           PetscCall(KSPView(*jac->ksp, sviewer));
213:           PetscCall(PetscViewerASCIIPopTab(sviewer));
214:         }
215:         PetscCall(PetscViewerRestoreSubViewer(viewer, mpjac->psubcomm->child, &sviewer));
216:         /*  extra call needed because of the two calls to PetscViewerASCIIPushSynchronized() in PetscViewerGetSubViewer() */
217:         PetscCall(PetscViewerASCIIPopSynchronized(viewer));
218:       }
219:     } else {
220:       PetscInt n_global;
221:       PetscCall(MPIU_Allreduce(&jac->n_local, &n_global, 1, MPIU_INT, MPI_MAX, PetscObjectComm((PetscObject)pc)));
222:       PetscCall(PetscViewerASCIIPushSynchronized(viewer));
223:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Local solver information for each block is in the following KSP and PC objects:\n"));
224:       PetscCall(PetscViewerASCIIPushTab(viewer));
225:       PetscCall(PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
226:       PetscCall(PetscViewerASCIIPrintf(sviewer, "[%d] number of local blocks = %" PetscInt_FMT ", first local block number = %" PetscInt_FMT "\n", rank, jac->n_local, jac->first_local));
227:       for (i = 0; i < jac->n_local; i++) {
228:         PetscCall(PetscViewerASCIIPrintf(sviewer, "[%d] local block number %" PetscInt_FMT "\n", rank, i));
229:         PetscCall(KSPView(jac->ksp[i], sviewer));
230:         PetscCall(PetscViewerASCIIPrintf(sviewer, "- - - - - - - - - - - - - - - - - -\n"));
231:       }
232:       PetscCall(PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
233:       PetscCall(PetscViewerASCIIPopTab(viewer));
234:       PetscCall(PetscViewerASCIIPopSynchronized(viewer));
235:     }
236:   } else if (isstring) {
237:     PetscCall(PetscViewerStringSPrintf(viewer, " blks=%" PetscInt_FMT, jac->n));
238:     PetscCall(PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
239:     if (jac->ksp) PetscCall(KSPView(jac->ksp[0], sviewer));
240:     PetscCall(PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
241:   } else if (isdraw) {
242:     PetscDraw draw;
243:     char      str[25];
244:     PetscReal x, y, bottom, h;

246:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
247:     PetscCall(PetscDrawGetCurrentPoint(draw, &x, &y));
248:     PetscCall(PetscSNPrintf(str, 25, "Number blocks %" PetscInt_FMT, jac->n));
249:     PetscCall(PetscDrawStringBoxed(draw, x, y, PETSC_DRAW_RED, PETSC_DRAW_BLACK, str, NULL, &h));
250:     bottom = y - h;
251:     PetscCall(PetscDrawPushCurrentPoint(draw, x, bottom));
252:     /* warning the communicator on viewer is different then on ksp in parallel */
253:     if (jac->ksp) PetscCall(KSPView(jac->ksp[0], viewer));
254:     PetscCall(PetscDrawPopCurrentPoint(draw));
255:   }
256:   PetscFunctionReturn(PETSC_SUCCESS);
257: }

259: static PetscErrorCode PCBJacobiGetSubKSP_BJacobi(PC pc, PetscInt *n_local, PetscInt *first_local, KSP **ksp)
260: {
261:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;

263:   PetscFunctionBegin;
264:   PetscCheck(pc->setupcalled, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "Must call KSPSetUp() or PCSetUp() first");

266:   if (n_local) *n_local = jac->n_local;
267:   if (first_local) *first_local = jac->first_local;
268:   if (ksp) *ksp = jac->ksp;
269:   PetscFunctionReturn(PETSC_SUCCESS);
270: }

272: static PetscErrorCode PCBJacobiSetTotalBlocks_BJacobi(PC pc, PetscInt blocks, const PetscInt *lens)
273: {
274:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;

276:   PetscFunctionBegin;
277:   PetscCheck(pc->setupcalled <= 0 || jac->n == blocks, PetscObjectComm((PetscObject)pc), PETSC_ERR_ORDER, "Cannot alter number of blocks after PCSetUp()/KSPSetUp() has been called");
278:   jac->n = blocks;
279:   if (!lens) jac->g_lens = NULL;
280:   else {
281:     PetscCall(PetscMalloc1(blocks, &jac->g_lens));
282:     PetscCall(PetscArraycpy(jac->g_lens, lens, blocks));
283:   }
284:   PetscFunctionReturn(PETSC_SUCCESS);
285: }

287: static PetscErrorCode PCBJacobiGetTotalBlocks_BJacobi(PC pc, PetscInt *blocks, const PetscInt *lens[])
288: {
289:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;

291:   PetscFunctionBegin;
292:   *blocks = jac->n;
293:   if (lens) *lens = jac->g_lens;
294:   PetscFunctionReturn(PETSC_SUCCESS);
295: }

297: static PetscErrorCode PCBJacobiSetLocalBlocks_BJacobi(PC pc, PetscInt blocks, const PetscInt lens[])
298: {
299:   PC_BJacobi *jac;

301:   PetscFunctionBegin;
302:   jac = (PC_BJacobi *)pc->data;

304:   jac->n_local = blocks;
305:   if (!lens) jac->l_lens = NULL;
306:   else {
307:     PetscCall(PetscMalloc1(blocks, &jac->l_lens));
308:     PetscCall(PetscArraycpy(jac->l_lens, lens, blocks));
309:   }
310:   PetscFunctionReturn(PETSC_SUCCESS);
311: }

313: static PetscErrorCode PCBJacobiGetLocalBlocks_BJacobi(PC pc, PetscInt *blocks, const PetscInt *lens[])
314: {
315:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;

317:   PetscFunctionBegin;
318:   *blocks = jac->n_local;
319:   if (lens) *lens = jac->l_lens;
320:   PetscFunctionReturn(PETSC_SUCCESS);
321: }

323: /*@C
324:   PCBJacobiGetSubKSP - Gets the local `KSP` contexts for all blocks on
325:   this processor.

327:   Not Collective

329:   Input Parameter:
330: . pc - the preconditioner context

332:   Output Parameters:
333: + n_local     - the number of blocks on this processor, or NULL
334: . first_local - the global number of the first block on this processor, or NULL
335: - ksp         - the array of KSP contexts

337:   Notes:
338:   After `PCBJacobiGetSubKSP()` the array of `KSP` contexts is not to be freed.

340:   Currently for some matrix implementations only 1 block per processor
341:   is supported.

343:   You must call `KSPSetUp()` or `PCSetUp()` before calling `PCBJacobiGetSubKSP()`.

345:   Fortran Notes:
346:   You must pass in a `KSP` array that is large enough to contain all the local `KSP`s.

348:   You can call `PCBJacobiGetSubKSP`(pc,nlocal,firstlocal,`PETSC_NULL_KSP`,ierr) to determine how large the
349:   `KSP` array must be.

351:   Level: advanced

353: .seealso: [](ch_ksp), `PCBJACOBI`, `PCASM`, `PCASMGetSubKSP()`
354: @*/
355: PetscErrorCode PCBJacobiGetSubKSP(PC pc, PetscInt *n_local, PetscInt *first_local, KSP *ksp[])
356: {
357:   PetscFunctionBegin;
359:   PetscUseMethod(pc, "PCBJacobiGetSubKSP_C", (PC, PetscInt *, PetscInt *, KSP **), (pc, n_local, first_local, ksp));
360:   PetscFunctionReturn(PETSC_SUCCESS);
361: }

363: /*@
364:   PCBJacobiSetTotalBlocks - Sets the global number of blocks for the block
365:   Jacobi preconditioner.

367:   Collective

369:   Input Parameters:
370: + pc     - the preconditioner context
371: . blocks - the number of blocks
372: - lens   - [optional] integer array containing the size of each block

374:   Options Database Key:
375: . -pc_bjacobi_blocks <blocks> - Sets the number of global blocks

377:   Note:
378:   Currently only a limited number of blocking configurations are supported.
379:   All processors sharing the `PC` must call this routine with the same data.

381:   Level: intermediate

383: .seealso: [](ch_ksp), `PCBJACOBI`, `PCSetUseAmat()`, `PCBJacobiSetLocalBlocks()`
384: @*/
385: PetscErrorCode PCBJacobiSetTotalBlocks(PC pc, PetscInt blocks, const PetscInt lens[])
386: {
387:   PetscFunctionBegin;
389:   PetscCheck(blocks > 0, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_OUTOFRANGE, "Must have positive blocks");
390:   PetscTryMethod(pc, "PCBJacobiSetTotalBlocks_C", (PC, PetscInt, const PetscInt[]), (pc, blocks, lens));
391:   PetscFunctionReturn(PETSC_SUCCESS);
392: }

394: /*@C
395:   PCBJacobiGetTotalBlocks - Gets the global number of blocks for the block
396:   Jacobi, `PCBJACOBI`, preconditioner.

398:   Not Collective

400:   Input Parameter:
401: . pc - the preconditioner context

403:   Output Parameters:
404: + blocks - the number of blocks
405: - lens   - integer array containing the size of each block

407:   Level: intermediate

409: .seealso: [](ch_ksp), `PCBJACOBI`, `PCSetUseAmat()`, `PCBJacobiGetLocalBlocks()`
410: @*/
411: PetscErrorCode PCBJacobiGetTotalBlocks(PC pc, PetscInt *blocks, const PetscInt *lens[])
412: {
413:   PetscFunctionBegin;
415:   PetscAssertPointer(blocks, 2);
416:   PetscUseMethod(pc, "PCBJacobiGetTotalBlocks_C", (PC, PetscInt *, const PetscInt *[]), (pc, blocks, lens));
417:   PetscFunctionReturn(PETSC_SUCCESS);
418: }

420: /*@
421:   PCBJacobiSetLocalBlocks - Sets the local number of blocks for the block
422:   Jacobi, `PCBJACOBI`,  preconditioner.

424:   Not Collective

426:   Input Parameters:
427: + pc     - the preconditioner context
428: . blocks - the number of blocks
429: - lens   - [optional] integer array containing size of each block

431:   Options Database Key:
432: . -pc_bjacobi_local_blocks <blocks> - Sets the number of local blocks

434:   Note:
435:   Currently only a limited number of blocking configurations are supported.

437:   Level: intermediate

439: .seealso: [](ch_ksp), `PCBJACOBI`, `PCSetUseAmat()`, `PCBJacobiSetTotalBlocks()`
440: @*/
441: PetscErrorCode PCBJacobiSetLocalBlocks(PC pc, PetscInt blocks, const PetscInt lens[])
442: {
443:   PetscFunctionBegin;
445:   PetscCheck(blocks >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Must have nonegative blocks");
446:   PetscTryMethod(pc, "PCBJacobiSetLocalBlocks_C", (PC, PetscInt, const PetscInt[]), (pc, blocks, lens));
447:   PetscFunctionReturn(PETSC_SUCCESS);
448: }

450: /*@C
451:   PCBJacobiGetLocalBlocks - Gets the local number of blocks for the block
452:   Jacobi, `PCBJACOBI`, preconditioner.

454:   Not Collective

456:   Input Parameters:
457: + pc     - the preconditioner context
458: . blocks - the number of blocks
459: - lens   - [optional] integer array containing size of each block

461:   Note:
462:   Currently only a limited number of blocking configurations are supported.

464:   Level: intermediate

466: .seealso: [](ch_ksp), `PCBJACOBI`, `PCSetUseAmat()`, `PCBJacobiGetTotalBlocks()`
467: @*/
468: PetscErrorCode PCBJacobiGetLocalBlocks(PC pc, PetscInt *blocks, const PetscInt *lens[])
469: {
470:   PetscFunctionBegin;
472:   PetscAssertPointer(blocks, 2);
473:   PetscUseMethod(pc, "PCBJacobiGetLocalBlocks_C", (PC, PetscInt *, const PetscInt *[]), (pc, blocks, lens));
474:   PetscFunctionReturn(PETSC_SUCCESS);
475: }

477: /*MC
478:    PCBJACOBI - Use block Jacobi preconditioning, each block is (approximately) solved with
479:            its own `KSP` object.

481:    Options Database Keys:
482: +  -pc_use_amat - use Amat to apply block of operator in inner Krylov method
483: -  -pc_bjacobi_blocks <n> - use n total blocks

485:    Notes:
486:     See `PCJACOBI` for diagonal Jacobi, `PCVPBJACOBI` for variable point block, and `PCPBJACOBI` for fixed size point block

488:     Each processor can have one or more blocks, or a single block can be shared by several processes. Defaults to one block per processor.

490:      To set options on the solvers for each block append -sub_ to all the `KSP` and `PC`
491:         options database keys. For example, -sub_pc_type ilu -sub_pc_factor_levels 1 -sub_ksp_type preonly

493:      To set the options on the solvers separate for each block call `PCBJacobiGetSubKSP()`
494:          and set the options directly on the resulting `KSP` object (you can access its `PC`
495:          `KSPGetPC()`)

497:      For GPU-based vectors (`VECCUDA`, `VECViennaCL`) it is recommended to use exactly one block per MPI process for best
498:          performance.  Different block partitioning may lead to additional data transfers
499:          between host and GPU that lead to degraded performance.

501:      When multiple processes share a single block, each block encompasses exactly all the unknowns owned its set of processes.

503:    Level: beginner

505: .seealso: [](ch_ksp), `PCCreate()`, `PCSetType()`, `PCType`, `PC`, `PCType`,
506:           `PCASM`, `PCSetUseAmat()`, `PCGetUseAmat()`, `PCBJacobiGetSubKSP()`, `PCBJacobiSetTotalBlocks()`,
507:           `PCBJacobiSetLocalBlocks()`, `PCSetModifySubMatrices()`, `PCJACOBI`, `PCVPBJACOBI`, `PCPBJACOBI`
508: M*/

510: PETSC_EXTERN PetscErrorCode PCCreate_BJacobi(PC pc)
511: {
512:   PetscMPIInt rank;
513:   PC_BJacobi *jac;

515:   PetscFunctionBegin;
516:   PetscCall(PetscNew(&jac));
517:   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank));

519:   pc->ops->apply           = NULL;
520:   pc->ops->matapply        = NULL;
521:   pc->ops->applytranspose  = NULL;
522:   pc->ops->setup           = PCSetUp_BJacobi;
523:   pc->ops->destroy         = PCDestroy_BJacobi;
524:   pc->ops->setfromoptions  = PCSetFromOptions_BJacobi;
525:   pc->ops->view            = PCView_BJacobi;
526:   pc->ops->applyrichardson = NULL;

528:   pc->data         = (void *)jac;
529:   jac->n           = -1;
530:   jac->n_local     = -1;
531:   jac->first_local = rank;
532:   jac->ksp         = NULL;
533:   jac->g_lens      = NULL;
534:   jac->l_lens      = NULL;
535:   jac->psubcomm    = NULL;

537:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiGetSubKSP_C", PCBJacobiGetSubKSP_BJacobi));
538:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiSetTotalBlocks_C", PCBJacobiSetTotalBlocks_BJacobi));
539:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiGetTotalBlocks_C", PCBJacobiGetTotalBlocks_BJacobi));
540:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiSetLocalBlocks_C", PCBJacobiSetLocalBlocks_BJacobi));
541:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCBJacobiGetLocalBlocks_C", PCBJacobiGetLocalBlocks_BJacobi));
542:   PetscFunctionReturn(PETSC_SUCCESS);
543: }

545: /*
546:         These are for a single block per processor; works for AIJ, BAIJ; Seq and MPI
547: */
548: static PetscErrorCode PCReset_BJacobi_Singleblock(PC pc)
549: {
550:   PC_BJacobi             *jac  = (PC_BJacobi *)pc->data;
551:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock *)jac->data;

553:   PetscFunctionBegin;
554:   PetscCall(KSPReset(jac->ksp[0]));
555:   PetscCall(VecDestroy(&bjac->x));
556:   PetscCall(VecDestroy(&bjac->y));
557:   PetscFunctionReturn(PETSC_SUCCESS);
558: }

560: static PetscErrorCode PCDestroy_BJacobi_Singleblock(PC pc)
561: {
562:   PC_BJacobi             *jac  = (PC_BJacobi *)pc->data;
563:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock *)jac->data;

565:   PetscFunctionBegin;
566:   PetscCall(PCReset_BJacobi_Singleblock(pc));
567:   PetscCall(KSPDestroy(&jac->ksp[0]));
568:   PetscCall(PetscFree(jac->ksp));
569:   PetscCall(PetscFree(bjac));
570:   PetscCall(PCDestroy_BJacobi(pc));
571:   PetscFunctionReturn(PETSC_SUCCESS);
572: }

574: static PetscErrorCode PCSetUpOnBlocks_BJacobi_Singleblock(PC pc)
575: {
576:   PC_BJacobi        *jac    = (PC_BJacobi *)pc->data;
577:   KSP                subksp = jac->ksp[0];
578:   KSPConvergedReason reason;

580:   PetscFunctionBegin;
581:   PetscCall(KSPSetUp(subksp));
582:   PetscCall(KSPGetConvergedReason(subksp, &reason));
583:   if (reason == KSP_DIVERGED_PC_FAILED) pc->failedreason = PC_SUBPC_ERROR;
584:   PetscFunctionReturn(PETSC_SUCCESS);
585: }

587: static PetscErrorCode PCApply_BJacobi_Singleblock(PC pc, Vec x, Vec y)
588: {
589:   PC_BJacobi             *jac  = (PC_BJacobi *)pc->data;
590:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock *)jac->data;

592:   PetscFunctionBegin;
593:   PetscCall(VecGetLocalVectorRead(x, bjac->x));
594:   PetscCall(VecGetLocalVector(y, bjac->y));
595:   /* Since the inner KSP matrix may point directly to the diagonal block of an MPI matrix the inner
596:      matrix may change even if the outer KSP/PC has not updated the preconditioner, this will trigger a rebuild
597:      of the inner preconditioner automatically unless we pass down the outer preconditioners reuse flag.*/
598:   PetscCall(KSPSetReusePreconditioner(jac->ksp[0], pc->reusepreconditioner));
599:   PetscCall(KSPSolve(jac->ksp[0], bjac->x, bjac->y));
600:   PetscCall(KSPCheckSolve(jac->ksp[0], pc, bjac->y));
601:   PetscCall(VecRestoreLocalVectorRead(x, bjac->x));
602:   PetscCall(VecRestoreLocalVector(y, bjac->y));
603:   PetscFunctionReturn(PETSC_SUCCESS);
604: }

606: static PetscErrorCode PCMatApply_BJacobi_Singleblock(PC pc, Mat X, Mat Y)
607: {
608:   PC_BJacobi *jac = (PC_BJacobi *)pc->data;
609:   Mat         sX, sY;

611:   PetscFunctionBegin;
612:   /* Since the inner KSP matrix may point directly to the diagonal block of an MPI matrix the inner
613:      matrix may change even if the outer KSP/PC has not updated the preconditioner, this will trigger a rebuild
614:      of the inner preconditioner automatically unless we pass down the outer preconditioners reuse flag.*/
615:   PetscCall(KSPSetReusePreconditioner(jac->ksp[0], pc->reusepreconditioner));
616:   PetscCall(MatDenseGetLocalMatrix(X, &sX));
617:   PetscCall(MatDenseGetLocalMatrix(Y, &sY));
618:   PetscCall(KSPMatSolve(jac->ksp[0], sX, sY));
619:   PetscFunctionReturn(PETSC_SUCCESS);
620: }

622: static PetscErrorCode PCApplySymmetricLeft_BJacobi_Singleblock(PC pc, Vec x, Vec y)
623: {
624:   PC_BJacobi             *jac  = (PC_BJacobi *)pc->data;
625:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock *)jac->data;
626:   PetscScalar            *y_array;
627:   const PetscScalar      *x_array;
628:   PC                      subpc;

630:   PetscFunctionBegin;
631:   /*
632:       The VecPlaceArray() is to avoid having to copy the
633:     y vector into the bjac->x vector. The reason for
634:     the bjac->x vector is that we need a sequential vector
635:     for the sequential solve.
636:   */
637:   PetscCall(VecGetArrayRead(x, &x_array));
638:   PetscCall(VecGetArray(y, &y_array));
639:   PetscCall(VecPlaceArray(bjac->x, x_array));
640:   PetscCall(VecPlaceArray(bjac->y, y_array));
641:   /* apply the symmetric left portion of the inner PC operator */
642:   /* note this by-passes the inner KSP and its options completely */
643:   PetscCall(KSPGetPC(jac->ksp[0], &subpc));
644:   PetscCall(PCApplySymmetricLeft(subpc, bjac->x, bjac->y));
645:   PetscCall(VecResetArray(bjac->x));
646:   PetscCall(VecResetArray(bjac->y));
647:   PetscCall(VecRestoreArrayRead(x, &x_array));
648:   PetscCall(VecRestoreArray(y, &y_array));
649:   PetscFunctionReturn(PETSC_SUCCESS);
650: }

652: static PetscErrorCode PCApplySymmetricRight_BJacobi_Singleblock(PC pc, Vec x, Vec y)
653: {
654:   PC_BJacobi             *jac  = (PC_BJacobi *)pc->data;
655:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock *)jac->data;
656:   PetscScalar            *y_array;
657:   const PetscScalar      *x_array;
658:   PC                      subpc;

660:   PetscFunctionBegin;
661:   /*
662:       The VecPlaceArray() is to avoid having to copy the
663:     y vector into the bjac->x vector. The reason for
664:     the bjac->x vector is that we need a sequential vector
665:     for the sequential solve.
666:   */
667:   PetscCall(VecGetArrayRead(x, &x_array));
668:   PetscCall(VecGetArray(y, &y_array));
669:   PetscCall(VecPlaceArray(bjac->x, x_array));
670:   PetscCall(VecPlaceArray(bjac->y, y_array));

672:   /* apply the symmetric right portion of the inner PC operator */
673:   /* note this by-passes the inner KSP and its options completely */

675:   PetscCall(KSPGetPC(jac->ksp[0], &subpc));
676:   PetscCall(PCApplySymmetricRight(subpc, bjac->x, bjac->y));

678:   PetscCall(VecResetArray(bjac->x));
679:   PetscCall(VecResetArray(bjac->y));
680:   PetscCall(VecRestoreArrayRead(x, &x_array));
681:   PetscCall(VecRestoreArray(y, &y_array));
682:   PetscFunctionReturn(PETSC_SUCCESS);
683: }

685: static PetscErrorCode PCApplyTranspose_BJacobi_Singleblock(PC pc, Vec x, Vec y)
686: {
687:   PC_BJacobi             *jac  = (PC_BJacobi *)pc->data;
688:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock *)jac->data;
689:   PetscScalar            *y_array;
690:   const PetscScalar      *x_array;

692:   PetscFunctionBegin;
693:   /*
694:       The VecPlaceArray() is to avoid having to copy the
695:     y vector into the bjac->x vector. The reason for
696:     the bjac->x vector is that we need a sequential vector
697:     for the sequential solve.
698:   */
699:   PetscCall(VecGetArrayRead(x, &x_array));
700:   PetscCall(VecGetArray(y, &y_array));
701:   PetscCall(VecPlaceArray(bjac->x, x_array));
702:   PetscCall(VecPlaceArray(bjac->y, y_array));
703:   PetscCall(KSPSolveTranspose(jac->ksp[0], bjac->x, bjac->y));
704:   PetscCall(KSPCheckSolve(jac->ksp[0], pc, bjac->y));
705:   PetscCall(VecResetArray(bjac->x));
706:   PetscCall(VecResetArray(bjac->y));
707:   PetscCall(VecRestoreArrayRead(x, &x_array));
708:   PetscCall(VecRestoreArray(y, &y_array));
709:   PetscFunctionReturn(PETSC_SUCCESS);
710: }

712: static PetscErrorCode PCSetUp_BJacobi_Singleblock(PC pc, Mat mat, Mat pmat)
713: {
714:   PC_BJacobi             *jac = (PC_BJacobi *)pc->data;
715:   PetscInt                m;
716:   KSP                     ksp;
717:   PC_BJacobi_Singleblock *bjac;
718:   PetscBool               wasSetup = PETSC_TRUE;
719:   VecType                 vectype;
720:   const char             *prefix;

722:   PetscFunctionBegin;
723:   if (!pc->setupcalled) {
724:     if (!jac->ksp) {
725:       PetscInt nestlevel;

727:       wasSetup = PETSC_FALSE;

729:       PetscCall(KSPCreate(PETSC_COMM_SELF, &ksp));
730:       PetscCall(PCGetKSPNestLevel(pc, &nestlevel));
731:       PetscCall(KSPSetNestLevel(ksp, nestlevel + 1));
732:       PetscCall(KSPSetErrorIfNotConverged(ksp, pc->erroriffailure));
733:       PetscCall(PetscObjectIncrementTabLevel((PetscObject)ksp, (PetscObject)pc, 1));
734:       PetscCall(KSPSetType(ksp, KSPPREONLY));
735:       PetscCall(PCGetOptionsPrefix(pc, &prefix));
736:       PetscCall(KSPSetOptionsPrefix(ksp, prefix));
737:       PetscCall(KSPAppendOptionsPrefix(ksp, "sub_"));

739:       pc->ops->reset               = PCReset_BJacobi_Singleblock;
740:       pc->ops->destroy             = PCDestroy_BJacobi_Singleblock;
741:       pc->ops->apply               = PCApply_BJacobi_Singleblock;
742:       pc->ops->matapply            = PCMatApply_BJacobi_Singleblock;
743:       pc->ops->applysymmetricleft  = PCApplySymmetricLeft_BJacobi_Singleblock;
744:       pc->ops->applysymmetricright = PCApplySymmetricRight_BJacobi_Singleblock;
745:       pc->ops->applytranspose      = PCApplyTranspose_BJacobi_Singleblock;
746:       pc->ops->setuponblocks       = PCSetUpOnBlocks_BJacobi_Singleblock;

748:       PetscCall(PetscMalloc1(1, &jac->ksp));
749:       jac->ksp[0] = ksp;

751:       PetscCall(PetscNew(&bjac));
752:       jac->data = (void *)bjac;
753:     } else {
754:       ksp  = jac->ksp[0];
755:       bjac = (PC_BJacobi_Singleblock *)jac->data;
756:     }

758:     /*
759:       The reason we need to generate these vectors is to serve
760:       as the right-hand side and solution vector for the solve on the
761:       block. We do not need to allocate space for the vectors since
762:       that is provided via VecPlaceArray() just before the call to
763:       KSPSolve() on the block.
764:     */
765:     PetscCall(MatGetSize(pmat, &m, &m));
766:     PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, m, NULL, &bjac->x));
767:     PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, m, NULL, &bjac->y));
768:     PetscCall(MatGetVecType(pmat, &vectype));
769:     PetscCall(VecSetType(bjac->x, vectype));
770:     PetscCall(VecSetType(bjac->y, vectype));
771:   } else {
772:     ksp  = jac->ksp[0];
773:     bjac = (PC_BJacobi_Singleblock *)jac->data;
774:   }
775:   PetscCall(KSPGetOptionsPrefix(ksp, &prefix));
776:   if (pc->useAmat) {
777:     PetscCall(KSPSetOperators(ksp, mat, pmat));
778:     PetscCall(MatSetOptionsPrefix(mat, prefix));
779:   } else {
780:     PetscCall(KSPSetOperators(ksp, pmat, pmat));
781:   }
782:   PetscCall(MatSetOptionsPrefix(pmat, prefix));
783:   if (!wasSetup && pc->setfromoptionscalled) {
784:     /* If PCSetFromOptions_BJacobi is called later, KSPSetFromOptions will be called at that time. */
785:     PetscCall(KSPSetFromOptions(ksp));
786:   }
787:   PetscFunctionReturn(PETSC_SUCCESS);
788: }

790: static PetscErrorCode PCReset_BJacobi_Multiblock(PC pc)
791: {
792:   PC_BJacobi            *jac  = (PC_BJacobi *)pc->data;
793:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock *)jac->data;
794:   PetscInt               i;

796:   PetscFunctionBegin;
797:   if (bjac && bjac->pmat) {
798:     PetscCall(MatDestroyMatrices(jac->n_local, &bjac->pmat));
799:     if (pc->useAmat) PetscCall(MatDestroyMatrices(jac->n_local, &bjac->mat));
800:   }

802:   for (i = 0; i < jac->n_local; i++) {
803:     PetscCall(KSPReset(jac->ksp[i]));
804:     if (bjac && bjac->x) {
805:       PetscCall(VecDestroy(&bjac->x[i]));
806:       PetscCall(VecDestroy(&bjac->y[i]));
807:       PetscCall(ISDestroy(&bjac->is[i]));
808:     }
809:   }
810:   PetscCall(PetscFree(jac->l_lens));
811:   PetscCall(PetscFree(jac->g_lens));
812:   PetscFunctionReturn(PETSC_SUCCESS);
813: }

815: static PetscErrorCode PCDestroy_BJacobi_Multiblock(PC pc)
816: {
817:   PC_BJacobi            *jac  = (PC_BJacobi *)pc->data;
818:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock *)jac->data;
819:   PetscInt               i;

821:   PetscFunctionBegin;
822:   PetscCall(PCReset_BJacobi_Multiblock(pc));
823:   if (bjac) {
824:     PetscCall(PetscFree2(bjac->x, bjac->y));
825:     PetscCall(PetscFree(bjac->starts));
826:     PetscCall(PetscFree(bjac->is));
827:   }
828:   PetscCall(PetscFree(jac->data));
829:   for (i = 0; i < jac->n_local; i++) PetscCall(KSPDestroy(&jac->ksp[i]));
830:   PetscCall(PetscFree(jac->ksp));
831:   PetscCall(PCDestroy_BJacobi(pc));
832:   PetscFunctionReturn(PETSC_SUCCESS);
833: }

835: static PetscErrorCode PCSetUpOnBlocks_BJacobi_Multiblock(PC pc)
836: {
837:   PC_BJacobi        *jac = (PC_BJacobi *)pc->data;
838:   PetscInt           i, n_local = jac->n_local;
839:   KSPConvergedReason reason;

841:   PetscFunctionBegin;
842:   for (i = 0; i < n_local; i++) {
843:     PetscCall(KSPSetUp(jac->ksp[i]));
844:     PetscCall(KSPGetConvergedReason(jac->ksp[i], &reason));
845:     if (reason == KSP_DIVERGED_PC_FAILED) pc->failedreason = PC_SUBPC_ERROR;
846:   }
847:   PetscFunctionReturn(PETSC_SUCCESS);
848: }

850: static PetscErrorCode PCApply_BJacobi_Multiblock(PC pc, Vec x, Vec y)
851: {
852:   PC_BJacobi            *jac = (PC_BJacobi *)pc->data;
853:   PetscInt               i, n_local = jac->n_local;
854:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock *)jac->data;
855:   PetscScalar           *yin;
856:   const PetscScalar     *xin;

858:   PetscFunctionBegin;
859:   PetscCall(VecGetArrayRead(x, &xin));
860:   PetscCall(VecGetArray(y, &yin));
861:   for (i = 0; i < n_local; i++) {
862:     /*
863:        To avoid copying the subvector from x into a workspace we instead
864:        make the workspace vector array point to the subpart of the array of
865:        the global vector.
866:     */
867:     PetscCall(VecPlaceArray(bjac->x[i], xin + bjac->starts[i]));
868:     PetscCall(VecPlaceArray(bjac->y[i], yin + bjac->starts[i]));

870:     PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));
871:     PetscCall(KSPSolve(jac->ksp[i], bjac->x[i], bjac->y[i]));
872:     PetscCall(KSPCheckSolve(jac->ksp[i], pc, bjac->y[i]));
873:     PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));

875:     PetscCall(VecResetArray(bjac->x[i]));
876:     PetscCall(VecResetArray(bjac->y[i]));
877:   }
878:   PetscCall(VecRestoreArrayRead(x, &xin));
879:   PetscCall(VecRestoreArray(y, &yin));
880:   PetscFunctionReturn(PETSC_SUCCESS);
881: }

883: static PetscErrorCode PCApplySymmetricLeft_BJacobi_Multiblock(PC pc, Vec x, Vec y)
884: {
885:   PC_BJacobi            *jac = (PC_BJacobi *)pc->data;
886:   PetscInt               i, n_local = jac->n_local;
887:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock *)jac->data;
888:   PetscScalar           *yin;
889:   const PetscScalar     *xin;
890:   PC                     subpc;

892:   PetscFunctionBegin;
893:   PetscCall(VecGetArrayRead(x, &xin));
894:   PetscCall(VecGetArray(y, &yin));
895:   for (i = 0; i < n_local; i++) {
896:     /*
897:        To avoid copying the subvector from x into a workspace we instead
898:        make the workspace vector array point to the subpart of the array of
899:        the global vector.
900:     */
901:     PetscCall(VecPlaceArray(bjac->x[i], xin + bjac->starts[i]));
902:     PetscCall(VecPlaceArray(bjac->y[i], yin + bjac->starts[i]));

904:     PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));
905:     /* apply the symmetric left portion of the inner PC operator */
906:     /* note this by-passes the inner KSP and its options completely */
907:     PetscCall(KSPGetPC(jac->ksp[i], &subpc));
908:     PetscCall(PCApplySymmetricLeft(subpc, bjac->x[i], bjac->y[i]));
909:     PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));

911:     PetscCall(VecResetArray(bjac->x[i]));
912:     PetscCall(VecResetArray(bjac->y[i]));
913:   }
914:   PetscCall(VecRestoreArrayRead(x, &xin));
915:   PetscCall(VecRestoreArray(y, &yin));
916:   PetscFunctionReturn(PETSC_SUCCESS);
917: }

919: static PetscErrorCode PCApplySymmetricRight_BJacobi_Multiblock(PC pc, Vec x, Vec y)
920: {
921:   PC_BJacobi            *jac = (PC_BJacobi *)pc->data;
922:   PetscInt               i, n_local = jac->n_local;
923:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock *)jac->data;
924:   PetscScalar           *yin;
925:   const PetscScalar     *xin;
926:   PC                     subpc;

928:   PetscFunctionBegin;
929:   PetscCall(VecGetArrayRead(x, &xin));
930:   PetscCall(VecGetArray(y, &yin));
931:   for (i = 0; i < n_local; i++) {
932:     /*
933:        To avoid copying the subvector from x into a workspace we instead
934:        make the workspace vector array point to the subpart of the array of
935:        the global vector.
936:     */
937:     PetscCall(VecPlaceArray(bjac->x[i], xin + bjac->starts[i]));
938:     PetscCall(VecPlaceArray(bjac->y[i], yin + bjac->starts[i]));

940:     PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));
941:     /* apply the symmetric left portion of the inner PC operator */
942:     /* note this by-passes the inner KSP and its options completely */
943:     PetscCall(KSPGetPC(jac->ksp[i], &subpc));
944:     PetscCall(PCApplySymmetricRight(subpc, bjac->x[i], bjac->y[i]));
945:     PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));

947:     PetscCall(VecResetArray(bjac->x[i]));
948:     PetscCall(VecResetArray(bjac->y[i]));
949:   }
950:   PetscCall(VecRestoreArrayRead(x, &xin));
951:   PetscCall(VecRestoreArray(y, &yin));
952:   PetscFunctionReturn(PETSC_SUCCESS);
953: }

955: static PetscErrorCode PCApplyTranspose_BJacobi_Multiblock(PC pc, Vec x, Vec y)
956: {
957:   PC_BJacobi            *jac = (PC_BJacobi *)pc->data;
958:   PetscInt               i, n_local = jac->n_local;
959:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock *)jac->data;
960:   PetscScalar           *yin;
961:   const PetscScalar     *xin;

963:   PetscFunctionBegin;
964:   PetscCall(VecGetArrayRead(x, &xin));
965:   PetscCall(VecGetArray(y, &yin));
966:   for (i = 0; i < n_local; i++) {
967:     /*
968:        To avoid copying the subvector from x into a workspace we instead
969:        make the workspace vector array point to the subpart of the array of
970:        the global vector.
971:     */
972:     PetscCall(VecPlaceArray(bjac->x[i], xin + bjac->starts[i]));
973:     PetscCall(VecPlaceArray(bjac->y[i], yin + bjac->starts[i]));

975:     PetscCall(PetscLogEventBegin(PC_ApplyTransposeOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));
976:     PetscCall(KSPSolveTranspose(jac->ksp[i], bjac->x[i], bjac->y[i]));
977:     PetscCall(KSPCheckSolve(jac->ksp[i], pc, bjac->y[i]));
978:     PetscCall(PetscLogEventEnd(PC_ApplyTransposeOnBlocks, jac->ksp[i], bjac->x[i], bjac->y[i], 0));

980:     PetscCall(VecResetArray(bjac->x[i]));
981:     PetscCall(VecResetArray(bjac->y[i]));
982:   }
983:   PetscCall(VecRestoreArrayRead(x, &xin));
984:   PetscCall(VecRestoreArray(y, &yin));
985:   PetscFunctionReturn(PETSC_SUCCESS);
986: }

988: static PetscErrorCode PCSetUp_BJacobi_Multiblock(PC pc, Mat mat, Mat pmat)
989: {
990:   PC_BJacobi            *jac = (PC_BJacobi *)pc->data;
991:   PetscInt               m, n_local, N, M, start, i;
992:   const char            *prefix;
993:   KSP                    ksp;
994:   Vec                    x, y;
995:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock *)jac->data;
996:   PC                     subpc;
997:   IS                     is;
998:   MatReuse               scall;
999:   VecType                vectype;
1000:   MatNullSpace          *nullsp_mat = NULL, *nullsp_pmat = NULL;

1002:   PetscFunctionBegin;
1003:   PetscCall(MatGetLocalSize(pc->pmat, &M, &N));

1005:   n_local = jac->n_local;

1007:   if (pc->useAmat) {
1008:     PetscBool same;
1009:     PetscCall(PetscObjectTypeCompare((PetscObject)mat, ((PetscObject)pmat)->type_name, &same));
1010:     PetscCheck(same, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_INCOMP, "Matrices not of same type");
1011:   }

1013:   if (!pc->setupcalled) {
1014:     PetscInt nestlevel;

1016:     scall = MAT_INITIAL_MATRIX;

1018:     if (!jac->ksp) {
1019:       pc->ops->reset               = PCReset_BJacobi_Multiblock;
1020:       pc->ops->destroy             = PCDestroy_BJacobi_Multiblock;
1021:       pc->ops->apply               = PCApply_BJacobi_Multiblock;
1022:       pc->ops->matapply            = NULL;
1023:       pc->ops->applysymmetricleft  = PCApplySymmetricLeft_BJacobi_Multiblock;
1024:       pc->ops->applysymmetricright = PCApplySymmetricRight_BJacobi_Multiblock;
1025:       pc->ops->applytranspose      = PCApplyTranspose_BJacobi_Multiblock;
1026:       pc->ops->setuponblocks       = PCSetUpOnBlocks_BJacobi_Multiblock;

1028:       PetscCall(PetscNew(&bjac));
1029:       PetscCall(PetscMalloc1(n_local, &jac->ksp));
1030:       PetscCall(PetscMalloc2(n_local, &bjac->x, n_local, &bjac->y));
1031:       PetscCall(PetscMalloc1(n_local, &bjac->starts));

1033:       jac->data = (void *)bjac;
1034:       PetscCall(PetscMalloc1(n_local, &bjac->is));

1036:       for (i = 0; i < n_local; i++) {
1037:         PetscCall(KSPCreate(PETSC_COMM_SELF, &ksp));
1038:         PetscCall(PCGetKSPNestLevel(pc, &nestlevel));
1039:         PetscCall(KSPSetNestLevel(ksp, nestlevel + 1));
1040:         PetscCall(KSPSetErrorIfNotConverged(ksp, pc->erroriffailure));
1041:         PetscCall(PetscObjectIncrementTabLevel((PetscObject)ksp, (PetscObject)pc, 1));
1042:         PetscCall(KSPSetType(ksp, KSPPREONLY));
1043:         PetscCall(KSPGetPC(ksp, &subpc));
1044:         PetscCall(PCGetOptionsPrefix(pc, &prefix));
1045:         PetscCall(KSPSetOptionsPrefix(ksp, prefix));
1046:         PetscCall(KSPAppendOptionsPrefix(ksp, "sub_"));

1048:         jac->ksp[i] = ksp;
1049:       }
1050:     } else {
1051:       bjac = (PC_BJacobi_Multiblock *)jac->data;
1052:     }

1054:     start = 0;
1055:     PetscCall(MatGetVecType(pmat, &vectype));
1056:     for (i = 0; i < n_local; i++) {
1057:       m = jac->l_lens[i];
1058:       /*
1059:       The reason we need to generate these vectors is to serve
1060:       as the right-hand side and solution vector for the solve on the
1061:       block. We do not need to allocate space for the vectors since
1062:       that is provided via VecPlaceArray() just before the call to
1063:       KSPSolve() on the block.

1065:       */
1066:       PetscCall(VecCreateSeq(PETSC_COMM_SELF, m, &x));
1067:       PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, m, NULL, &y));
1068:       PetscCall(VecSetType(x, vectype));
1069:       PetscCall(VecSetType(y, vectype));

1071:       bjac->x[i]      = x;
1072:       bjac->y[i]      = y;
1073:       bjac->starts[i] = start;

1075:       PetscCall(ISCreateStride(PETSC_COMM_SELF, m, start, 1, &is));
1076:       bjac->is[i] = is;

1078:       start += m;
1079:     }
1080:   } else {
1081:     bjac = (PC_BJacobi_Multiblock *)jac->data;
1082:     /*
1083:        Destroy the blocks from the previous iteration
1084:     */
1085:     if (pc->flag == DIFFERENT_NONZERO_PATTERN) {
1086:       PetscCall(MatGetNullSpaces(n_local, bjac->pmat, &nullsp_pmat));
1087:       PetscCall(MatDestroyMatrices(n_local, &bjac->pmat));
1088:       if (pc->useAmat) {
1089:         PetscCall(MatGetNullSpaces(n_local, bjac->mat, &nullsp_mat));
1090:         PetscCall(MatDestroyMatrices(n_local, &bjac->mat));
1091:       }
1092:       scall = MAT_INITIAL_MATRIX;
1093:     } else scall = MAT_REUSE_MATRIX;
1094:   }

1096:   PetscCall(MatCreateSubMatrices(pmat, n_local, bjac->is, bjac->is, scall, &bjac->pmat));
1097:   if (nullsp_pmat) PetscCall(MatRestoreNullSpaces(n_local, bjac->pmat, &nullsp_pmat));
1098:   if (pc->useAmat) {
1099:     PetscCall(MatCreateSubMatrices(mat, n_local, bjac->is, bjac->is, scall, &bjac->mat));
1100:     if (nullsp_mat) PetscCall(MatRestoreNullSpaces(n_local, bjac->mat, &nullsp_mat));
1101:   }
1102:   /* Return control to the user so that the submatrices can be modified (e.g., to apply
1103:      different boundary conditions for the submatrices than for the global problem) */
1104:   PetscCall(PCModifySubMatrices(pc, n_local, bjac->is, bjac->is, bjac->pmat, pc->modifysubmatricesP));

1106:   for (i = 0; i < n_local; i++) {
1107:     PetscCall(KSPGetOptionsPrefix(jac->ksp[i], &prefix));
1108:     if (pc->useAmat) {
1109:       PetscCall(KSPSetOperators(jac->ksp[i], bjac->mat[i], bjac->pmat[i]));
1110:       PetscCall(MatSetOptionsPrefix(bjac->mat[i], prefix));
1111:     } else {
1112:       PetscCall(KSPSetOperators(jac->ksp[i], bjac->pmat[i], bjac->pmat[i]));
1113:     }
1114:     PetscCall(MatSetOptionsPrefix(bjac->pmat[i], prefix));
1115:     if (pc->setfromoptionscalled) PetscCall(KSPSetFromOptions(jac->ksp[i]));
1116:   }
1117:   PetscFunctionReturn(PETSC_SUCCESS);
1118: }

1120: /*
1121:       These are for a single block with multiple processes
1122: */
1123: static PetscErrorCode PCSetUpOnBlocks_BJacobi_Multiproc(PC pc)
1124: {
1125:   PC_BJacobi        *jac    = (PC_BJacobi *)pc->data;
1126:   KSP                subksp = jac->ksp[0];
1127:   KSPConvergedReason reason;

1129:   PetscFunctionBegin;
1130:   PetscCall(KSPSetUp(subksp));
1131:   PetscCall(KSPGetConvergedReason(subksp, &reason));
1132:   if (reason == KSP_DIVERGED_PC_FAILED) pc->failedreason = PC_SUBPC_ERROR;
1133:   PetscFunctionReturn(PETSC_SUCCESS);
1134: }

1136: static PetscErrorCode PCReset_BJacobi_Multiproc(PC pc)
1137: {
1138:   PC_BJacobi           *jac   = (PC_BJacobi *)pc->data;
1139:   PC_BJacobi_Multiproc *mpjac = (PC_BJacobi_Multiproc *)jac->data;

1141:   PetscFunctionBegin;
1142:   PetscCall(VecDestroy(&mpjac->ysub));
1143:   PetscCall(VecDestroy(&mpjac->xsub));
1144:   PetscCall(MatDestroy(&mpjac->submats));
1145:   if (jac->ksp) PetscCall(KSPReset(jac->ksp[0]));
1146:   PetscFunctionReturn(PETSC_SUCCESS);
1147: }

1149: static PetscErrorCode PCDestroy_BJacobi_Multiproc(PC pc)
1150: {
1151:   PC_BJacobi           *jac   = (PC_BJacobi *)pc->data;
1152:   PC_BJacobi_Multiproc *mpjac = (PC_BJacobi_Multiproc *)jac->data;

1154:   PetscFunctionBegin;
1155:   PetscCall(PCReset_BJacobi_Multiproc(pc));
1156:   PetscCall(KSPDestroy(&jac->ksp[0]));
1157:   PetscCall(PetscFree(jac->ksp));
1158:   PetscCall(PetscSubcommDestroy(&mpjac->psubcomm));

1160:   PetscCall(PetscFree(mpjac));
1161:   PetscCall(PCDestroy_BJacobi(pc));
1162:   PetscFunctionReturn(PETSC_SUCCESS);
1163: }

1165: static PetscErrorCode PCApply_BJacobi_Multiproc(PC pc, Vec x, Vec y)
1166: {
1167:   PC_BJacobi           *jac   = (PC_BJacobi *)pc->data;
1168:   PC_BJacobi_Multiproc *mpjac = (PC_BJacobi_Multiproc *)jac->data;
1169:   PetscScalar          *yarray;
1170:   const PetscScalar    *xarray;
1171:   KSPConvergedReason    reason;

1173:   PetscFunctionBegin;
1174:   /* place x's and y's local arrays into xsub and ysub */
1175:   PetscCall(VecGetArrayRead(x, &xarray));
1176:   PetscCall(VecGetArray(y, &yarray));
1177:   PetscCall(VecPlaceArray(mpjac->xsub, xarray));
1178:   PetscCall(VecPlaceArray(mpjac->ysub, yarray));

1180:   /* apply preconditioner on each matrix block */
1181:   PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, jac->ksp[0], mpjac->xsub, mpjac->ysub, 0));
1182:   PetscCall(KSPSolve(jac->ksp[0], mpjac->xsub, mpjac->ysub));
1183:   PetscCall(KSPCheckSolve(jac->ksp[0], pc, mpjac->ysub));
1184:   PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, jac->ksp[0], mpjac->xsub, mpjac->ysub, 0));
1185:   PetscCall(KSPGetConvergedReason(jac->ksp[0], &reason));
1186:   if (reason == KSP_DIVERGED_PC_FAILED) pc->failedreason = PC_SUBPC_ERROR;

1188:   PetscCall(VecResetArray(mpjac->xsub));
1189:   PetscCall(VecResetArray(mpjac->ysub));
1190:   PetscCall(VecRestoreArrayRead(x, &xarray));
1191:   PetscCall(VecRestoreArray(y, &yarray));
1192:   PetscFunctionReturn(PETSC_SUCCESS);
1193: }

1195: static PetscErrorCode PCMatApply_BJacobi_Multiproc(PC pc, Mat X, Mat Y)
1196: {
1197:   PC_BJacobi        *jac = (PC_BJacobi *)pc->data;
1198:   KSPConvergedReason reason;
1199:   Mat                sX, sY;
1200:   const PetscScalar *x;
1201:   PetscScalar       *y;
1202:   PetscInt           m, N, lda, ldb;

1204:   PetscFunctionBegin;
1205:   /* apply preconditioner on each matrix block */
1206:   PetscCall(MatGetLocalSize(X, &m, NULL));
1207:   PetscCall(MatGetSize(X, NULL, &N));
1208:   PetscCall(MatDenseGetLDA(X, &lda));
1209:   PetscCall(MatDenseGetLDA(Y, &ldb));
1210:   PetscCall(MatDenseGetArrayRead(X, &x));
1211:   PetscCall(MatDenseGetArrayWrite(Y, &y));
1212:   PetscCall(MatCreateDense(PetscObjectComm((PetscObject)jac->ksp[0]), m, PETSC_DECIDE, PETSC_DECIDE, N, (PetscScalar *)x, &sX));
1213:   PetscCall(MatCreateDense(PetscObjectComm((PetscObject)jac->ksp[0]), m, PETSC_DECIDE, PETSC_DECIDE, N, y, &sY));
1214:   PetscCall(MatDenseSetLDA(sX, lda));
1215:   PetscCall(MatDenseSetLDA(sY, ldb));
1216:   PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, jac->ksp[0], X, Y, 0));
1217:   PetscCall(KSPMatSolve(jac->ksp[0], sX, sY));
1218:   PetscCall(KSPCheckSolve(jac->ksp[0], pc, NULL));
1219:   PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, jac->ksp[0], X, Y, 0));
1220:   PetscCall(MatDestroy(&sY));
1221:   PetscCall(MatDestroy(&sX));
1222:   PetscCall(MatDenseRestoreArrayWrite(Y, &y));
1223:   PetscCall(MatDenseRestoreArrayRead(X, &x));
1224:   PetscCall(KSPGetConvergedReason(jac->ksp[0], &reason));
1225:   if (reason == KSP_DIVERGED_PC_FAILED) pc->failedreason = PC_SUBPC_ERROR;
1226:   PetscFunctionReturn(PETSC_SUCCESS);
1227: }

1229: static PetscErrorCode PCSetUp_BJacobi_Multiproc(PC pc)
1230: {
1231:   PC_BJacobi           *jac   = (PC_BJacobi *)pc->data;
1232:   PC_BJacobi_Multiproc *mpjac = (PC_BJacobi_Multiproc *)jac->data;
1233:   PetscInt              m, n;
1234:   MPI_Comm              comm, subcomm = 0;
1235:   const char           *prefix;
1236:   PetscBool             wasSetup = PETSC_TRUE;
1237:   VecType               vectype;

1239:   PetscFunctionBegin;
1240:   PetscCall(PetscObjectGetComm((PetscObject)pc, &comm));
1241:   PetscCheck(jac->n_local <= 1, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Only a single block in a subcommunicator is supported");
1242:   jac->n_local = 1; /* currently only a single block is supported for a subcommunicator */
1243:   if (!pc->setupcalled) {
1244:     PetscInt nestlevel;

1246:     wasSetup = PETSC_FALSE;
1247:     PetscCall(PetscNew(&mpjac));
1248:     jac->data = (void *)mpjac;

1250:     /* initialize datastructure mpjac */
1251:     if (!jac->psubcomm) {
1252:       /* Create default contiguous subcommunicatiors if user does not provide them */
1253:       PetscCall(PetscSubcommCreate(comm, &jac->psubcomm));
1254:       PetscCall(PetscSubcommSetNumber(jac->psubcomm, jac->n));
1255:       PetscCall(PetscSubcommSetType(jac->psubcomm, PETSC_SUBCOMM_CONTIGUOUS));
1256:     }
1257:     mpjac->psubcomm = jac->psubcomm;
1258:     subcomm         = PetscSubcommChild(mpjac->psubcomm);

1260:     /* Get matrix blocks of pmat */
1261:     PetscCall(MatGetMultiProcBlock(pc->pmat, subcomm, MAT_INITIAL_MATRIX, &mpjac->submats));

1263:     /* create a new PC that processors in each subcomm have copy of */
1264:     PetscCall(PetscMalloc1(1, &jac->ksp));
1265:     PetscCall(KSPCreate(subcomm, &jac->ksp[0]));
1266:     PetscCall(PCGetKSPNestLevel(pc, &nestlevel));
1267:     PetscCall(KSPSetNestLevel(jac->ksp[0], nestlevel + 1));
1268:     PetscCall(KSPSetErrorIfNotConverged(jac->ksp[0], pc->erroriffailure));
1269:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)jac->ksp[0], (PetscObject)pc, 1));
1270:     PetscCall(KSPSetOperators(jac->ksp[0], mpjac->submats, mpjac->submats));
1271:     PetscCall(KSPGetPC(jac->ksp[0], &mpjac->pc));

1273:     PetscCall(PCGetOptionsPrefix(pc, &prefix));
1274:     PetscCall(KSPSetOptionsPrefix(jac->ksp[0], prefix));
1275:     PetscCall(KSPAppendOptionsPrefix(jac->ksp[0], "sub_"));
1276:     PetscCall(KSPGetOptionsPrefix(jac->ksp[0], &prefix));
1277:     PetscCall(MatSetOptionsPrefix(mpjac->submats, prefix));

1279:     /* create dummy vectors xsub and ysub */
1280:     PetscCall(MatGetLocalSize(mpjac->submats, &m, &n));
1281:     PetscCall(VecCreateMPIWithArray(subcomm, 1, n, PETSC_DECIDE, NULL, &mpjac->xsub));
1282:     PetscCall(VecCreateMPIWithArray(subcomm, 1, m, PETSC_DECIDE, NULL, &mpjac->ysub));
1283:     PetscCall(MatGetVecType(mpjac->submats, &vectype));
1284:     PetscCall(VecSetType(mpjac->xsub, vectype));
1285:     PetscCall(VecSetType(mpjac->ysub, vectype));

1287:     pc->ops->setuponblocks = PCSetUpOnBlocks_BJacobi_Multiproc;
1288:     pc->ops->reset         = PCReset_BJacobi_Multiproc;
1289:     pc->ops->destroy       = PCDestroy_BJacobi_Multiproc;
1290:     pc->ops->apply         = PCApply_BJacobi_Multiproc;
1291:     pc->ops->matapply      = PCMatApply_BJacobi_Multiproc;
1292:   } else { /* pc->setupcalled */
1293:     subcomm = PetscSubcommChild(mpjac->psubcomm);
1294:     if (pc->flag == DIFFERENT_NONZERO_PATTERN) {
1295:       /* destroy old matrix blocks, then get new matrix blocks */
1296:       if (mpjac->submats) PetscCall(MatDestroy(&mpjac->submats));
1297:       PetscCall(MatGetMultiProcBlock(pc->pmat, subcomm, MAT_INITIAL_MATRIX, &mpjac->submats));
1298:     } else {
1299:       PetscCall(MatGetMultiProcBlock(pc->pmat, subcomm, MAT_REUSE_MATRIX, &mpjac->submats));
1300:     }
1301:     PetscCall(KSPSetOperators(jac->ksp[0], mpjac->submats, mpjac->submats));
1302:   }

1304:   if (!wasSetup && pc->setfromoptionscalled) PetscCall(KSPSetFromOptions(jac->ksp[0]));
1305:   PetscFunctionReturn(PETSC_SUCCESS);
1306: }