Actual source code: redundant.c
1: #define PETSCKSP_DLL
3: /*
4: This file defines a "solve the problem redundantly on each subgroup of processor" preconditioner.
5: */
6: #include private/pcimpl.h
7: #include petscksp.h
9: typedef struct {
10: KSP ksp;
11: PC pc; /* actual preconditioner used on each processor */
12: Vec xsub,ysub; /* vectors of a subcommunicator to hold parallel vectors of ((PetscObject)pc)->comm */
13: Vec xdup,ydup; /* parallel vector that congregates xsub or ysub facilitating vector scattering */
14: Mat pmats; /* matrix and optional preconditioner matrix belong to a subcommunicator */
15: VecScatter scatterin,scatterout; /* scatter used to move all values to each processor group (subcommunicator) */
16: PetscTruth useparallelmat;
17: PetscSubcomm psubcomm;
18: PetscInt nsubcomm; /* num of data structure PetscSubcomm */
19: } PC_Redundant;
23: static PetscErrorCode PCView_Redundant(PC pc,PetscViewer viewer)
24: {
25: PC_Redundant *red = (PC_Redundant*)pc->data;
27: PetscMPIInt rank;
28: PetscTruth iascii,isstring;
29: PetscViewer subviewer;
32: MPI_Comm_rank(((PetscObject)pc)->comm,&rank);
33: PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_ASCII,&iascii);
34: PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_STRING,&isstring);
35: if (iascii) {
36: if (!red->psubcomm) {
37: PetscViewerASCIIPrintf(viewer," Redundant preconditioner: Not yet setup\n");
38: } else {
39: PetscViewerASCIIPrintf(viewer," Redundant preconditioner: First (color=0) of %D PCs follows\n",red->nsubcomm);
40: PetscViewerGetSubcomm(viewer,((PetscObject)red->pc)->comm,&subviewer);
41: if (red->psubcomm->color) { /* only view first redundant pc */
42: PetscViewerASCIIPushTab(viewer);
43: KSPView(red->ksp,subviewer);
44: PetscViewerASCIIPopTab(viewer);
45: }
46: PetscViewerRestoreSubcomm(viewer,((PetscObject)red->pc)->comm,&subviewer);
47: }
48: } else if (isstring) {
49: PetscViewerStringSPrintf(viewer," Redundant solver preconditioner");
50: } else {
51: SETERRQ1(PETSC_ERR_SUP,"Viewer type %s not supported for PC redundant",((PetscObject)viewer)->type_name);
52: }
53: return(0);
54: }
56: #include private/matimpl.h
59: static PetscErrorCode PCSetUp_Redundant(PC pc)
60: {
61: PC_Redundant *red = (PC_Redundant*)pc->data;
63: PetscInt mstart,mend,mlocal,m,mlocal_sub,rstart_sub,rend_sub,mloc_sub;
64: PetscMPIInt size;
65: MatReuse reuse = MAT_INITIAL_MATRIX;
66: MatStructure str = DIFFERENT_NONZERO_PATTERN;
67: MPI_Comm comm = ((PetscObject)pc)->comm,subcomm;
68: Vec vec;
69: PetscMPIInt subsize,subrank;
70: const char *prefix;
73: MatGetVecs(pc->pmat,&vec,0);
74: VecGetSize(vec,&m);
76: if (!pc->setupcalled) {
77: if (!red->psubcomm) {
78: PetscSubcommCreate(comm,red->nsubcomm,&red->psubcomm);
79: PetscLogObjectMemory(pc,sizeof(PetscSubcomm));
81: /* create a new PC that processors in each subcomm have copy of */
82: subcomm = red->psubcomm->comm;
83: KSPCreate(subcomm,&red->ksp);
84: PetscObjectIncrementTabLevel((PetscObject)red->ksp,(PetscObject)pc,1);
85: PetscLogObjectParent(pc,red->ksp);
86: KSPSetType(red->ksp,KSPPREONLY);
87: KSPGetPC(red->ksp,&red->pc);
88: PCSetType(red->pc,PCLU);
90: PCGetOptionsPrefix(pc,&prefix);
91: KSPSetOptionsPrefix(red->ksp,prefix);
92: KSPAppendOptionsPrefix(red->ksp,"redundant_");
93: } else {
94: subcomm = red->psubcomm->comm;
95: }
97: /* create working vectors xsub/ysub and xdup/ydup */
98: VecGetLocalSize(vec,&mlocal);
99: VecGetOwnershipRange(vec,&mstart,&mend);
101: /* get local size of xsub/ysub */
102: MPI_Comm_size(subcomm,&subsize);
103: MPI_Comm_rank(subcomm,&subrank);
104: rstart_sub = pc->pmat->rmap->range[red->psubcomm->n*subrank]; /* rstart in xsub/ysub */
105: if (subrank+1 < subsize){
106: rend_sub = pc->pmat->rmap->range[red->psubcomm->n*(subrank+1)];
107: } else {
108: rend_sub = m;
109: }
110: mloc_sub = rend_sub - rstart_sub;
111: VecCreateMPI(subcomm,mloc_sub,PETSC_DECIDE,&red->ysub);
112: /* create xsub with empty local arrays, because xdup's arrays will be placed into it */
113: VecCreateMPIWithArray(subcomm,mloc_sub,PETSC_DECIDE,PETSC_NULL,&red->xsub);
115: /* create xdup and ydup. ydup has empty local arrays because ysub's arrays will be place into it.
116: Note: we use communicator dupcomm, not ((PetscObject)pc)->comm! */
117: VecCreateMPI(red->psubcomm->dupparent,mloc_sub,PETSC_DECIDE,&red->xdup);
118: VecCreateMPIWithArray(red->psubcomm->dupparent,mloc_sub,PETSC_DECIDE,PETSC_NULL,&red->ydup);
119:
120: /* create vec scatters */
121: if (!red->scatterin){
122: IS is1,is2;
123: PetscInt *idx1,*idx2,i,j,k;
125: PetscMalloc2(red->psubcomm->n*mlocal,PetscInt,&idx1,red->psubcomm->n*mlocal,PetscInt,&idx2);
126: j = 0;
127: for (k=0; k<red->psubcomm->n; k++){
128: for (i=mstart; i<mend; i++){
129: idx1[j] = i;
130: idx2[j++] = i + m*k;
131: }
132: }
133: ISCreateGeneral(comm,red->psubcomm->n*mlocal,idx1,&is1);
134: ISCreateGeneral(comm,red->psubcomm->n*mlocal,idx2,&is2);
135: VecScatterCreate(vec,is1,red->xdup,is2,&red->scatterin);
136: ISDestroy(is1);
137: ISDestroy(is2);
139: ISCreateStride(comm,mlocal,mstart+ red->psubcomm->color*m,1,&is1);
140: ISCreateStride(comm,mlocal,mstart,1,&is2);
141: VecScatterCreate(red->xdup,is1,vec,is2,&red->scatterout);
142: ISDestroy(is1);
143: ISDestroy(is2);
144: PetscFree2(idx1,idx2);
145: }
146: }
147: VecDestroy(vec);
149: /* if pmatrix set by user is sequential then we do not need to gather the parallel matrix */
150: MPI_Comm_size(comm,&size);
151: if (size == 1) {
152: red->useparallelmat = PETSC_FALSE;
153: }
155: if (red->useparallelmat) {
156: if (pc->setupcalled == 1 && pc->flag == DIFFERENT_NONZERO_PATTERN) {
157: /* destroy old matrices */
158: if (red->pmats) {
159: MatDestroy(red->pmats);
160: }
161: } else if (pc->setupcalled == 1) {
162: reuse = MAT_REUSE_MATRIX;
163: str = SAME_NONZERO_PATTERN;
164: }
165:
166: /* grab the parallel matrix and put it into processors of a subcomminicator */
167: /*--------------------------------------------------------------------------*/
168: VecGetLocalSize(red->ysub,&mlocal_sub);
169: MatGetRedundantMatrix(pc->pmat,red->psubcomm->n,red->psubcomm->comm,mlocal_sub,reuse,&red->pmats);
170: /* tell PC of the subcommunicator its operators */
171: KSPSetOperators(red->ksp,red->pmats,red->pmats,str);
172: } else {
173: KSPSetOperators(red->ksp,pc->mat,pc->pmat,pc->flag);
174: }
175: if (pc->setfromoptionscalled){
176: KSPSetFromOptions(red->ksp);
177: }
178: KSPSetUp(red->ksp);
179: return(0);
180: }
184: static PetscErrorCode PCApply_Redundant(PC pc,Vec x,Vec y)
185: {
186: PC_Redundant *red = (PC_Redundant*)pc->data;
188: PetscScalar *array;
191: /* scatter x to xdup */
192: VecScatterBegin(red->scatterin,x,red->xdup,INSERT_VALUES,SCATTER_FORWARD);
193: VecScatterEnd(red->scatterin,x,red->xdup,INSERT_VALUES,SCATTER_FORWARD);
194:
195: /* place xdup's local array into xsub */
196: VecGetArray(red->xdup,&array);
197: VecPlaceArray(red->xsub,(const PetscScalar*)array);
199: /* apply preconditioner on each processor */
200: PCApply(red->pc,red->xsub,red->ysub);
201: VecResetArray(red->xsub);
202: VecRestoreArray(red->xdup,&array);
203:
204: /* place ysub's local array into ydup */
205: VecGetArray(red->ysub,&array);
206: VecPlaceArray(red->ydup,(const PetscScalar*)array);
208: /* scatter ydup to y */
209: VecScatterBegin(red->scatterout,red->ydup,y,INSERT_VALUES,SCATTER_FORWARD);
210: VecScatterEnd(red->scatterout,red->ydup,y,INSERT_VALUES,SCATTER_FORWARD);
211: VecResetArray(red->ydup);
212: VecRestoreArray(red->ysub,&array);
213: return(0);
214: }
218: static PetscErrorCode PCDestroy_Redundant(PC pc)
219: {
220: PC_Redundant *red = (PC_Redundant*)pc->data;
224: if (red->scatterin) {VecScatterDestroy(red->scatterin);}
225: if (red->scatterout) {VecScatterDestroy(red->scatterout);}
226: if (red->ysub) {VecDestroy(red->ysub);}
227: if (red->xsub) {VecDestroy(red->xsub);}
228: if (red->xdup) {VecDestroy(red->xdup);}
229: if (red->ydup) {VecDestroy(red->ydup);}
230: if (red->pmats) {
231: MatDestroy(red->pmats);
232: }
233: if (red->psubcomm) {PetscSubcommDestroy(red->psubcomm);}
234: if (red->ksp) {KSPDestroy(red->ksp);}
235: PetscFree(red);
236: return(0);
237: }
241: static PetscErrorCode PCSetFromOptions_Redundant(PC pc)
242: {
244: PC_Redundant *red = (PC_Redundant*)pc->data;
247: PetscOptionsHead("Redundant options");
248: PetscOptionsInt("-pc_redundant_number","Number of redundant pc","PCRedundantSetNumber",red->nsubcomm,&red->nsubcomm,0);
249: PetscOptionsTail();
250: return(0);
251: }
256: PetscErrorCode PCRedundantSetNumber_Redundant(PC pc,PetscInt nreds)
257: {
258: PC_Redundant *red = (PC_Redundant*)pc->data;
261: red->nsubcomm = nreds;
262: return(0);
263: }
268: /*@
269: PCRedundantSetNumber - Sets the number of redundant preconditioner contexts.
271: Collective on PC
273: Input Parameters:
274: + pc - the preconditioner context
275: - nredundant - number of redundant preconditioner contexts; for example if you are using 64 MPI processes and
276: use an nredundant of 4 there will be 4 parallel solves each on 16 = 64/4 processes.
278: Level: advanced
280: .keywords: PC, redundant solve
281: @*/
282: PetscErrorCode PCRedundantSetNumber(PC pc,PetscInt nredundant)
283: {
284: PetscErrorCode ierr,(*f)(PC,PetscInt);
288: if (nredundant <= 0) SETERRQ1(PETSC_ERR_ARG_WRONG, "num of redundant pc %D must be positive",nredundant);
289: PetscObjectQueryFunction((PetscObject)pc,"PCRedundantSetNumber_C",(void (**)(void))&f);
290: if (f) {
291: (*f)(pc,nredundant);
292: }
293: return(0);
294: }
299: PetscErrorCode PCRedundantSetScatter_Redundant(PC pc,VecScatter in,VecScatter out)
300: {
301: PC_Redundant *red = (PC_Redundant*)pc->data;
305: PetscObjectReference((PetscObject)in);
306: if (red->scatterin) { VecScatterDestroy(red->scatterin); }
307: red->scatterin = in;
308: PetscObjectReference((PetscObject)out);
309: if (red->scatterout) { VecScatterDestroy(red->scatterout); }
310: red->scatterout = out;
311: return(0);
312: }
317: /*@
318: PCRedundantSetScatter - Sets the scatter used to copy values into the
319: redundant local solve and the scatter to move them back into the global
320: vector.
322: Collective on PC
324: Input Parameters:
325: + pc - the preconditioner context
326: . in - the scatter to move the values in
327: - out - the scatter to move them out
329: Level: advanced
331: .keywords: PC, redundant solve
332: @*/
333: PetscErrorCode PCRedundantSetScatter(PC pc,VecScatter in,VecScatter out)
334: {
335: PetscErrorCode ierr,(*f)(PC,VecScatter,VecScatter);
341: PetscObjectQueryFunction((PetscObject)pc,"PCRedundantSetScatter_C",(void (**)(void))&f);
342: if (f) {
343: (*f)(pc,in,out);
344: }
345: return(0);
346: }
351: PetscErrorCode PCRedundantGetPC_Redundant(PC pc,PC *innerpc)
352: {
354: PC_Redundant *red = (PC_Redundant*)pc->data;
355: MPI_Comm comm,subcomm;
356: const char *prefix;
359: if (!red->psubcomm) {
360: PetscObjectGetComm((PetscObject)pc,&comm);
361: PetscSubcommCreate(comm,red->nsubcomm,&red->psubcomm);
362: PetscLogObjectMemory(pc,sizeof(PetscSubcomm));
364: /* create a new PC that processors in each subcomm have copy of */
365: subcomm = red->psubcomm->comm;
366: KSPCreate(subcomm,&red->ksp);
367: PetscObjectIncrementTabLevel((PetscObject)red->ksp,(PetscObject)pc,1);
368: PetscLogObjectParent(pc,red->ksp);
369: KSPSetType(red->ksp,KSPPREONLY);
370: KSPGetPC(red->ksp,&red->pc);
371: PCSetType(red->pc,PCLU);
373: PCGetOptionsPrefix(pc,&prefix);
374: KSPSetOptionsPrefix(red->ksp,prefix);
375: KSPAppendOptionsPrefix(red->ksp,"redundant_");
376: }
378: KSPGetPC(red->ksp,innerpc);
379: return(0);
380: }
385: /*@
386: PCRedundantGetPC - Gets the sequential PC created by the redundant PC.
388: Not Collective
390: Input Parameter:
391: . pc - the preconditioner context
393: Output Parameter:
394: . innerpc - the sequential PC
396: Level: advanced
398: .keywords: PC, redundant solve
399: @*/
400: PetscErrorCode PCRedundantGetPC(PC pc,PC *innerpc)
401: {
402: PetscErrorCode ierr,(*f)(PC,PC*);
407: PetscObjectQueryFunction((PetscObject)pc,"PCRedundantGetPC_C",(void (**)(void))&f);
408: if (f) {
409: (*f)(pc,innerpc);
410: }
411: return(0);
412: }
417: PetscErrorCode PCRedundantGetOperators_Redundant(PC pc,Mat *mat,Mat *pmat)
418: {
419: PC_Redundant *red = (PC_Redundant*)pc->data;
422: if (mat) *mat = red->pmats;
423: if (pmat) *pmat = red->pmats;
424: return(0);
425: }
430: /*@
431: PCRedundantGetOperators - gets the sequential matrix and preconditioner matrix
433: Not Collective
435: Input Parameter:
436: . pc - the preconditioner context
438: Output Parameters:
439: + mat - the matrix
440: - pmat - the (possibly different) preconditioner matrix
442: Level: advanced
444: .keywords: PC, redundant solve
445: @*/
446: PetscErrorCode PCRedundantGetOperators(PC pc,Mat *mat,Mat *pmat)
447: {
448: PetscErrorCode ierr,(*f)(PC,Mat*,Mat*);
454: PetscObjectQueryFunction((PetscObject)pc,"PCRedundantGetOperators_C",(void (**)(void))&f);
455: if (f) {
456: (*f)(pc,mat,pmat);
457: }
458: return(0);
459: }
461: /* -------------------------------------------------------------------------------------*/
462: /*MC
463: PCREDUNDANT - Runs a preconditioner for the entire problem on subgroups of processors
465: Options for the redundant preconditioners can be set with -redundant_pc_xxx
467: Options Database:
468: . -pc_redundant_number <n> - number of redundant solves, for example if you are using 64 MPI processes and
469: use an n of 4 there will be 4 parallel solves each on 16 = 64/4 processes.
471: Level: intermediate
473: .seealso: PCCreate(), PCSetType(), PCType (for list of available types), PCRedundantSetScatter(),
474: PCRedundantGetPC(), PCRedundantGetOperators(), PCRedundantSetNumber()
475: M*/
480: PetscErrorCode PCCreate_Redundant(PC pc)
481: {
483: PC_Redundant *red;
484: PetscMPIInt size;
485:
487: PetscNewLog(pc,PC_Redundant,&red);
488: MPI_Comm_size(((PetscObject)pc)->comm,&size);
489: red->nsubcomm = size;
490: red->useparallelmat = PETSC_TRUE;
491: pc->data = (void*)red;
493: pc->ops->apply = PCApply_Redundant;
494: pc->ops->applytranspose = 0;
495: pc->ops->setup = PCSetUp_Redundant;
496: pc->ops->destroy = PCDestroy_Redundant;
497: pc->ops->setfromoptions = PCSetFromOptions_Redundant;
498: pc->ops->view = PCView_Redundant;
499: PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCRedundantSetScatter_C","PCRedundantSetScatter_Redundant",
500: PCRedundantSetScatter_Redundant);
501: PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCRedundantSetNumber_C","PCRedundantSetNumber_Redundant",
502: PCRedundantSetNumber_Redundant);
503: PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCRedundantGetPC_C","PCRedundantGetPC_Redundant",
504: PCRedundantGetPC_Redundant);
505: PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCRedundantGetOperators_C","PCRedundantGetOperators_Redundant",
506: PCRedundantGetOperators_Redundant);
507: return(0);
508: }