Actual source code: hpc.c
petsc-3.3-p7 2013-05-11
2: #include <petsc-private/pcimpl.h> /*I "petscpc.h" I*/
3: #include <petscksp.h>
5: typedef struct {
6: MatStructure flag; /* pc->flag */
7: PetscInt setupcalled; /* pc->setupcalled */
8: PetscInt n;
9: MPI_Comm comm; /* local world used by this preconditioner */
10: KSP ksp; /* actual solver used across local world */
11: Mat mat; /* matrix in local world */
12: Mat gmat; /* matrix known only to process 0 in the local world */
13: Vec x,y,xdummy,ydummy;
14: VecScatter scatter;
15: PetscBool nonzero_guess;
16: } PC_HMPI;
21: /*
22: Would like to have this simply call PCView() on the inner PC. The problem is
23: that the outer comm does not live on the inside so cannot do this. Instead
24: handle the special case when the viewer is stdout, construct a new one just
25: for this call.
26: */
28: static PetscErrorCode PCView_HMPI_MP(MPI_Comm comm,void *ctx)
29: {
30: PC_HMPI *red = (PC_HMPI*)ctx;
32: PetscViewer viewer;
35: PetscViewerASCIIGetStdout(comm,&viewer);
36: PetscViewerASCIIPushTab(viewer); /* this is bogus in general */
37: KSPView(red->ksp,viewer);
38: PetscViewerASCIIPopTab(viewer);
39: return(0);
40: }
44: static PetscErrorCode PCView_HMPI(PC pc,PetscViewer viewer)
45: {
46: PC_HMPI *red = (PC_HMPI*)pc->data;
47: PetscMPIInt size;
49: PetscBool iascii;
54: MPI_Comm_size(red->comm,&size);
55: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
56: if (iascii) {
57: PetscViewerASCIIPrintf(viewer," Size of solver nodes %d\n",size);
58: PetscViewerASCIIPrintf(viewer," Parallel sub-solver given next\n",size);
59: /* should only make the next call if the viewer is associated with stdout */
60: PetscHMPIRun(red->comm,PCView_HMPI_MP,red);
61: }
62: return(0);
63: }
65: extern PetscErrorCode MatDistribute_MPIAIJ(MPI_Comm,Mat,PetscInt,MatReuse,Mat*);
69: static PetscErrorCode PCApply_HMPI_1(PC pc,Vec x,Vec y)
70: {
71: PC_HMPI *red = (PC_HMPI*)pc->data;
75: KSPSetInitialGuessNonzero(red->ksp,pc->nonzero_guess);
76: KSPSolve(red->ksp,x,y);
77: return(0);
78: }
82: static PetscErrorCode PCSetUp_HMPI_MP(MPI_Comm comm,void *ctx)
83: {
84: PC_HMPI *red = (PC_HMPI*)ctx;
86: PetscInt m;
87: MatReuse scal;
88: PetscMPIInt rank;
91: red->comm = comm;
92: MPI_Bcast(&red->setupcalled,1,MPIU_INT,0,comm);
93: MPI_Bcast(&red->flag,1,MPIU_INT,0,comm);
94: if (!red->setupcalled) {
95: /* setup vector communication */
96: MPI_Bcast(&red->n,1,MPIU_INT,0,comm);
97: VecCreateMPI(comm,PETSC_DECIDE,red->n,&red->x);
98: VecCreateMPI(comm,PETSC_DECIDE,red->n,&red->y);
99: VecScatterCreateToZero(red->x,&red->scatter,&red->xdummy);
100: VecDuplicate(red->xdummy,&red->ydummy);
101: MPI_Comm_rank(comm,&rank);
102: if (!rank) {
103: VecDestroy(&red->xdummy);
104: VecDestroy(&red->ydummy);
105: }
106: scal = MAT_INITIAL_MATRIX;
107: } else {
108: if (red->flag == DIFFERENT_NONZERO_PATTERN) {
109: MatDestroy(&red->mat);
110: scal = MAT_INITIAL_MATRIX;
111: CHKMEMQ;
112: } else {
113: scal = MAT_REUSE_MATRIX;
114: }
115: }
117: /* copy matrix out onto processes */
118: VecGetLocalSize(red->x,&m);
119: MatDistribute_MPIAIJ(comm,red->gmat,m,scal,&red->mat);
120: if (!red->setupcalled) {
121: /* create the solver */
122: KSPCreate(comm,&red->ksp);
123: /* would like to set proper tablevel for KSP, but do not have direct access to parent pc */
124: KSPSetOptionsPrefix(red->ksp,"hmpi_"); /* should actually append with global pc prefix */
125: KSPSetOperators(red->ksp,red->mat,red->mat,red->flag);
126: KSPSetFromOptions(red->ksp);
127: } else {
128: KSPSetOperators(red->ksp,red->mat,red->mat,red->flag);
129: }
130: return(0);
131: }
135: static PetscErrorCode PCSetUp_HMPI(PC pc)
136: {
137: PC_HMPI *red = (PC_HMPI*)pc->data;
139: PetscMPIInt size;
142: red->gmat = pc->mat;
143: red->flag = pc->flag;
144: red->setupcalled = pc->setupcalled;
146: MPI_Comm_size(red->comm,&size);
147: if (size == 1) { /* special case where copy of matrix is not needed */
148: if (!red->setupcalled) {
149: /* create the solver */
150: KSPCreate(((PetscObject)pc)->comm,&red->ksp);
151: PetscObjectIncrementTabLevel((PetscObject)red->ksp,(PetscObject)pc,1);
152: KSPSetOptionsPrefix(red->ksp,"hmpi_"); /* should actually append with global pc prefix */
153: KSPSetOperators(red->ksp,red->gmat,red->gmat,red->flag);
154: KSPSetFromOptions(red->ksp);
155: } else {
156: KSPSetOperators(red->ksp,red->gmat,red->gmat,red->flag);
157: }
158: pc->ops->apply = PCApply_HMPI_1;
159: return(0);
160: } else {
161: MatGetSize(pc->mat,&red->n,PETSC_IGNORE);
162: PetscHMPIRun(red->comm,PCSetUp_HMPI_MP,red);
163: }
164: return(0);
165: }
169: static PetscErrorCode PCApply_HMPI_MP(MPI_Comm comm,void *ctx)
170: {
171: PC_HMPI *red = (PC_HMPI*)ctx;
175: VecScatterBegin(red->scatter,red->xdummy,red->x,INSERT_VALUES,SCATTER_REVERSE);
176: VecScatterEnd(red->scatter,red->xdummy,red->x,INSERT_VALUES,SCATTER_REVERSE);
177: MPI_Bcast(&red->nonzero_guess,1,MPIU_INT,0,red->comm);
178: if (red->nonzero_guess) {
179: VecScatterBegin(red->scatter,red->ydummy,red->y,INSERT_VALUES,SCATTER_REVERSE);
180: VecScatterEnd(red->scatter,red->ydummy,red->y,INSERT_VALUES,SCATTER_REVERSE);
181: }
182: KSPSetInitialGuessNonzero(red->ksp,red->nonzero_guess);
184: KSPSolve(red->ksp,red->x,red->y);
186: VecScatterBegin(red->scatter,red->y,red->ydummy,INSERT_VALUES,SCATTER_FORWARD);
187: VecScatterEnd(red->scatter,red->y,red->ydummy,INSERT_VALUES,SCATTER_FORWARD);
188: return(0);
189: }
193: static PetscErrorCode PCApply_HMPI(PC pc,Vec x,Vec y)
194: {
195: PC_HMPI *red = (PC_HMPI*)pc->data;
199: red->xdummy = x;
200: red->ydummy = y;
201: red->nonzero_guess = pc->nonzero_guess;
202: PetscHMPIRun(red->comm,PCApply_HMPI_MP,red);
203: return(0);
204: }
208: static PetscErrorCode PCDestroy_HMPI_MP(MPI_Comm comm,void *ctx)
209: {
210: PC_HMPI *red = (PC_HMPI*)ctx;
211: PetscMPIInt rank;
215: VecScatterDestroy(&red->scatter);
216: VecDestroy(&red->x);
217: VecDestroy(&red->y);
218: KSPDestroy(&red->ksp);
219: MatDestroy(&red->mat);
220: MPI_Comm_rank(comm,&rank);
221: if (rank) {
222: VecDestroy(&red->xdummy);
223: VecDestroy(&red->ydummy);
224: }
225: return(0);
226: }
230: static PetscErrorCode PCDestroy_HMPI(PC pc)
231: {
232: PC_HMPI *red = (PC_HMPI*)pc->data;
236: PetscHMPIRun(red->comm,PCDestroy_HMPI_MP,red);
237: PetscHMPIFree(red->comm,red);
238: return(0);
239: }
243: static PetscErrorCode PCSetFromOptions_HMPI(PC pc)
244: {
246: return(0);
247: }
250: /* -------------------------------------------------------------------------------------*/
251: /*MC
252: PCHMPI - Runs a preconditioner for a single process matrix across several MPI processes
254: $ This will usually be run with -pc_type hmpi -ksp_type preonly
255: $ solver options are set with -hmpi_ksp_... and -hmpi_pc_... for example
256: $ -hmpi_ksp_type cg would use cg as the Krylov method or -hmpi_ksp_monitor or
257: $ -hmpi_pc_type hypre -hmpi_pc_hypre_type boomeramg
259: Always run with -ksp_view (or -snes_view) to see what solver is actually being used.
261: Currently the solver options INSIDE the HMPI preconditioner can ONLY be set via the
262: options database.
264: Level: intermediate
266: See PetscHMPIMerge() and PetscHMPISpawn() for two ways to start up MPI for use with this preconditioner
268: .seealso: PCCreate(), PCSetType(), PCType (for list of available types)
270: M*/
272: EXTERN_C_BEGIN
275: PetscErrorCode PCCreate_HMPI(PC pc)
276: {
278: PC_HMPI *red;
279: PetscMPIInt size;
282: MPI_Comm_size(((PetscObject)pc)->comm,&size);
283: if (size > 1) SETERRQ(((PetscObject)pc)->comm,PETSC_ERR_ARG_SIZ,"HMPI preconditioner only works for sequential solves");
284: /* caste the struct length to a PetscInt for easier MPI calls */
286: PetscHMPIMalloc(PETSC_COMM_LOCAL_WORLD,(PetscInt)sizeof(PC_HMPI),(void**)&red);
287: red->comm = PETSC_COMM_LOCAL_WORLD;
288: pc->data = (void*) red;
290: pc->ops->apply = PCApply_HMPI;
291: pc->ops->destroy = PCDestroy_HMPI;
292: pc->ops->setfromoptions = PCSetFromOptions_HMPI;
293: pc->ops->setup = PCSetUp_HMPI;
294: pc->ops->view = PCView_HMPI;
295: return(0);
296: }
297: EXTERN_C_END