Actual source code: ex10.c

  1: static char help[] = "Solve a small system and a large system through preloading\n\
  2:   Input arguments are:\n\
  3:   -permute <natural,rcm,nd,...> : solve system in permuted indexing\n\
  4:   -f0 <small_sys_binary> -f1 <large_sys_binary> \n\n";

  6: /*
  7:   Include "petscksp.h" so that we can use KSP solvers.  Note that this file
  8:   automatically includes:
  9:      petscsys.h       - base PETSc routines   petscvec.h - vectors
 10:      petscmat.h - matrices
 11:      petscis.h     - index sets            petscksp.h - Krylov subspace methods
 12:      petscviewer.h - viewers               petscpc.h  - preconditioners
 13: */
 14: #include <petscksp.h>

 16: typedef enum {
 17:   RHS_FILE,
 18:   RHS_ONE,
 19:   RHS_RANDOM
 20: } RHSType;
 21: const char *const RHSTypes[] = {"FILE", "ONE", "RANDOM", "RHSType", "RHS_", NULL};

 23: PetscErrorCode CheckResult(KSP *ksp, Mat *A, Vec *b, Vec *x, IS *rowperm)
 24: {
 25:   PetscReal norm; /* norm of solution error */
 26:   PetscInt  its;
 27:   PetscFunctionBegin;
 28:   PetscCall(KSPGetTotalIterations(*ksp, &its));
 29:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Number of iterations = %" PetscInt_FMT "\n", its));

 31:   PetscCall(KSPGetResidualNorm(*ksp, &norm));
 32:   if (norm < 1.e-12) {
 33:     PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Residual norm < 1.e-12\n"));
 34:   } else {
 35:     PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Residual norm %e\n", (double)norm));
 36:   }

 38:   PetscCall(KSPDestroy(ksp));
 39:   PetscCall(MatDestroy(A));
 40:   PetscCall(VecDestroy(x));
 41:   PetscCall(VecDestroy(b));
 42:   PetscCall(ISDestroy(rowperm));
 43:   PetscFunctionReturn(PETSC_SUCCESS);
 44: }

 46: PetscErrorCode CreateSystem(const char filename[PETSC_MAX_PATH_LEN], RHSType rhstype, MatOrderingType ordering, PetscBool permute, IS *colperm_out, Mat *A_out, Vec *b_out, Vec *x_out)
 47: {
 48:   Vec                x, b, b2;
 49:   Mat                A;      /* linear system matrix */
 50:   PetscViewer        viewer; /* viewer */
 51:   PetscBool          same;
 52:   PetscInt           j, len, start, idx, n1, n2;
 53:   const PetscScalar *val;
 54:   IS                 rowperm = NULL, colperm = NULL;

 56:   PetscFunctionBegin;
 57:   /* open binary file. Note that we use FILE_MODE_READ to indicate reading from this file */
 58:   PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD, filename, FILE_MODE_READ, &viewer));

 60:   /* load the matrix and vector; then destroy the viewer */
 61:   PetscCall(MatCreate(PETSC_COMM_WORLD, &A));
 62:   PetscCall(MatSetFromOptions(A));
 63:   PetscCall(MatLoad(A, viewer));
 64:   switch (rhstype) {
 65:   case RHS_FILE:
 66:     /* Vectors in the file might a different size than the matrix so we need a
 67:      * Vec whose size hasn't been set yet.  It'll get fixed below.  Otherwise we
 68:      * can create the correct size Vec. */
 69:     PetscCall(VecCreate(PETSC_COMM_WORLD, &b));
 70:     PetscCall(VecLoad(b, viewer));
 71:     break;
 72:   case RHS_ONE:
 73:     PetscCall(MatCreateVecs(A, &b, NULL));
 74:     PetscCall(VecSet(b, 1.0));
 75:     break;
 76:   case RHS_RANDOM:
 77:     PetscCall(MatCreateVecs(A, &b, NULL));
 78:     PetscCall(VecSetRandom(b, NULL));
 79:     break;
 80:   }
 81:   PetscCall(PetscViewerDestroy(&viewer));

 83:   /* if the loaded matrix is larger than the vector (due to being padded
 84:      to match the block size of the system), then create a new padded vector
 85:    */
 86:   PetscCall(MatGetLocalSize(A, NULL, &n1));
 87:   PetscCall(VecGetLocalSize(b, &n2));
 88:   same = (n1 == n2) ? PETSC_TRUE : PETSC_FALSE;
 89:   PetscCall(MPIU_Allreduce(MPI_IN_PLACE, &same, 1, MPIU_BOOL, MPI_LAND, PETSC_COMM_WORLD));

 91:   if (!same) { /* create a new vector b by padding the old one */
 92:     PetscCall(VecCreate(PETSC_COMM_WORLD, &b2));
 93:     PetscCall(VecSetSizes(b2, n1, PETSC_DECIDE));
 94:     PetscCall(VecSetFromOptions(b2));
 95:     PetscCall(VecGetOwnershipRange(b, &start, NULL));
 96:     PetscCall(VecGetLocalSize(b, &len));
 97:     PetscCall(VecGetArrayRead(b, &val));
 98:     for (j = 0; j < len; j++) {
 99:       idx = start + j;
100:       PetscCall(VecSetValues(b2, 1, &idx, val + j, INSERT_VALUES));
101:     }
102:     PetscCall(VecRestoreArrayRead(b, &val));
103:     PetscCall(VecDestroy(&b));
104:     PetscCall(VecAssemblyBegin(b2));
105:     PetscCall(VecAssemblyEnd(b2));
106:     b = b2;
107:   }
108:   PetscCall(VecDuplicate(b, &x));

110:   if (permute) {
111:     Mat Aperm;
112:     PetscCall(MatGetOrdering(A, ordering, &rowperm, &colperm));
113:     PetscCall(MatPermute(A, rowperm, colperm, &Aperm));
114:     PetscCall(VecPermute(b, rowperm, PETSC_FALSE));
115:     PetscCall(MatDestroy(&A));
116:     A = Aperm; /* Replace original operator with permuted version */
117:     PetscCall(ISDestroy(&rowperm));
118:   }

120:   *b_out       = b;
121:   *x_out       = x;
122:   *A_out       = A;
123:   *colperm_out = colperm;

125:   PetscFunctionReturn(PETSC_SUCCESS);
126: }

128: /* ATTENTION: this is the example used in the Profiling chapter of the PETSc manual,
129:    where we referenced its profiling stages, preloading and output etc.
130:    When you modify it, please make sure it is still consistent with the manual.
131:  */
132: int main(int argc, char **args)
133: {
134:   Vec       x, b;
135:   Mat       A;   /* linear system matrix */
136:   KSP       ksp; /* Krylov subspace method context */
137:   char      file[2][PETSC_MAX_PATH_LEN], ordering[256] = MATORDERINGRCM;
138:   RHSType   rhstype = RHS_FILE;
139:   PetscBool flg, preload = PETSC_FALSE, trans = PETSC_FALSE, permute = PETSC_FALSE;
140:   IS        colperm = NULL;

142:   PetscFunctionBeginUser;
143:   PetscCall(PetscInitialize(&argc, &args, (char *)0, help));

145:   PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "Preloading example options", "");
146:   {
147:     /*
148:        Determine files from which we read the two linear systems
149:        (matrix and right-hand-side vector).
150:     */
151:     PetscCall(PetscOptionsBool("-trans", "Solve transpose system instead", "", trans, &trans, &flg));
152:     PetscCall(PetscOptionsString("-f", "First file to load (small system)", "", file[0], file[0], sizeof(file[0]), &flg));
153:     PetscCall(PetscOptionsFList("-permute", "Permute matrix and vector to solve in new ordering", "", MatOrderingList, ordering, ordering, sizeof(ordering), &permute));

155:     if (flg) {
156:       PetscCall(PetscStrncpy(file[1], file[0], sizeof(file[1])));
157:       preload = PETSC_FALSE;
158:     } else {
159:       PetscCall(PetscOptionsString("-f0", "First file to load (small system)", "", file[0], file[0], sizeof(file[0]), &flg));
160:       PetscCheck(flg, PETSC_COMM_WORLD, PETSC_ERR_USER_INPUT, "Must indicate binary file with the -f0 or -f option");
161:       PetscCall(PetscOptionsString("-f1", "Second file to load (larger system)", "", file[1], file[1], sizeof(file[1]), &flg));
162:       if (!flg) preload = PETSC_FALSE; /* don't bother with second system */
163:     }

165:     PetscCall(PetscOptionsEnum("-rhs", "Right hand side", "", RHSTypes, (PetscEnum)rhstype, (PetscEnum *)&rhstype, NULL));
166:   }
167:   PetscOptionsEnd();

169:   /*
170:     To use preloading, one usually has code like the following:

172:     PetscPreLoadBegin(preload,"first stage);
173:       lines of code
174:     PetscPreLoadStage("second stage");
175:       lines of code
176:     PetscPreLoadEnd();

178:     The two macro PetscPreLoadBegin() and PetscPreLoadEnd() implicitly form a
179:     loop with maximal two iterations, depending whether preloading is turned on or
180:     not. If it is, either through the preload arg of PetscPreLoadBegin or through
181:     -preload command line, the trip count is 2, otherwise it is 1. One can use the
182:     predefined variable PetscPreLoadIt within the loop body to get the current
183:     iteration number, which is 0 or 1. If preload is turned on, the runtime doesn't
184:     do profiling for the first iteration, but it will do profiling for the second
185:     iteration instead.

187:     One can solve a small system in the first iteration and a large system in
188:     the second iteration. This process preloads the instructions with the small
189:     system so that more accurate performance monitoring (via -log_view) can be done
190:     with the large one (that actually is the system of interest).

192:     But in this example, we turned off preloading and duplicated the code for
193:     the large system. In general, it is a bad practice and one should not duplicate
194:     code. We do that because we want to show profiling stages for both the small
195:     system and the large system.
196:   */

198:   /*=========================
199:       solve a small system
200:     =========================*/

202:   PetscPreLoadBegin(preload, "Load System 0");
203:   PetscCall(CreateSystem(file[0], rhstype, ordering, permute, &colperm, &A, &b, &x));

205:   PetscPreLoadStage("KSPSetUp 0");
206:   PetscCall(KSPCreate(PETSC_COMM_WORLD, &ksp));
207:   PetscCall(KSPSetOperators(ksp, A, A));
208:   PetscCall(KSPSetFromOptions(ksp));

210:   /*
211:     Here we explicitly call KSPSetUp() and KSPSetUpOnBlocks() to
212:     enable more precise profiling of setting up the preconditioner.
213:     These calls are optional, since both will be called within
214:     KSPSolve() if they haven't been called already.
215:   */
216:   PetscCall(KSPSetUp(ksp));
217:   PetscCall(KSPSetUpOnBlocks(ksp));

219:   PetscPreLoadStage("KSPSolve 0");
220:   if (trans) PetscCall(KSPSolveTranspose(ksp, b, x));
221:   else PetscCall(KSPSolve(ksp, b, x));

223:   if (permute) PetscCall(VecPermute(x, colperm, PETSC_TRUE));

225:   PetscCall(CheckResult(&ksp, &A, &b, &x, &colperm));

227:   /*=========================
228:     solve a large system
229:     =========================*/

231:   PetscPreLoadStage("Load System 1");

233:   PetscCall(CreateSystem(file[1], rhstype, ordering, permute, &colperm, &A, &b, &x));

235:   PetscPreLoadStage("KSPSetUp 1");
236:   PetscCall(KSPCreate(PETSC_COMM_WORLD, &ksp));
237:   PetscCall(KSPSetOperators(ksp, A, A));
238:   PetscCall(KSPSetFromOptions(ksp));

240:   /*
241:     Here we explicitly call KSPSetUp() and KSPSetUpOnBlocks() to
242:     enable more precise profiling of setting up the preconditioner.
243:     These calls are optional, since both will be called within
244:     KSPSolve() if they haven't been called already.
245:   */
246:   PetscCall(KSPSetUp(ksp));
247:   PetscCall(KSPSetUpOnBlocks(ksp));

249:   PetscPreLoadStage("KSPSolve 1");
250:   if (trans) PetscCall(KSPSolveTranspose(ksp, b, x));
251:   else PetscCall(KSPSolve(ksp, b, x));

253:   if (permute) PetscCall(VecPermute(x, colperm, PETSC_TRUE));

255:   PetscCall(CheckResult(&ksp, &A, &b, &x, &colperm));

257:   PetscPreLoadEnd();
258:   /*
259:      Always call PetscFinalize() before exiting a program.  This routine
260:        - finalizes the PETSc libraries as well as MPI
261:        - provides summary and diagnostic information if certain runtime
262:          options are chosen (e.g., -log_view).
263:   */
264:   PetscCall(PetscFinalize());
265:   return 0;
266: }

268: /*TEST

270:    test:
271:       TODO: Matrix row/column sizes are not compatible with block size
272:       suffix: 1
273:       nsize: 4
274:       output_file: output/ex10_1.out
275:       requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)
276:       args: -f0 ${DATAFILESPATH}/matrices/medium -f1 ${DATAFILESPATH}/matrices/arco6 -ksp_gmres_classicalgramschmidt -mat_type baij -matload_block_size 3 -pc_type bjacobi

278:    test:
279:       TODO: Matrix row/column sizes are not compatible with block size
280:       suffix: 2
281:       nsize: 4
282:       output_file: output/ex10_2.out
283:       requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)
284:       args: -f0 ${DATAFILESPATH}/matrices/medium -f1 ${DATAFILESPATH}/matrices/arco6 -ksp_gmres_classicalgramschmidt -mat_type baij -matload_block_size 3 -pc_type bjacobi -trans

286:    test:
287:       suffix: 3
288:       requires: double complex !defined(PETSC_USE_64BIT_INDICES)
289:       args: -f ${wPETSC_DIR}/share/petsc/datafiles/matrices/nh-complex-int32-float64 -ksp_type bicg

291:    test:
292:       suffix: 4
293:       args: -f ${DATAFILESPATH}/matrices/medium -ksp_type bicg -permute rcm
294:       requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES)

296: TEST*/