Actual source code: ex14.c


  2: static char help[] = "Test event log of VecScatter with various block sizes\n\n";

  4: #include <petscvec.h>

  6: int main(int argc, char **argv)
  7: {
  8:   PetscInt           i, j, low, high, n = 256, N, errors, tot_errors;
  9:   PetscInt           bs = 1, ix[2], iy[2];
 10:   PetscMPIInt        nproc, rank;
 11:   PetscScalar       *xval;
 12:   const PetscScalar *yval;
 13:   Vec                x, y;
 14:   IS                 isx, isy;
 15:   VecScatter         ctx;
 16:   const PetscInt     niter = 10;
 17: #if defined(PETSC_USE_LOG)
 18:   PetscLogStage      stage1, stage2;
 19:   PetscLogEvent      event1, event2;
 20:   PetscLogDouble     numMessages, messageLength;
 21:   PetscEventPerfInfo eventInfo;
 22:   PetscInt           tot_msg, tot_len, avg_len;
 23: #endif

 25:   PetscFunctionBegin;
 26:   PetscFunctionBeginUser;
 27:   PetscCall(PetscInitialize(&argc, &argv, (char *)0, help));
 28:   PetscCall(PetscLogDefaultBegin());
 29:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &nproc));
 30:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));

 32:   PetscCall(PetscLogStageRegister("Scatter(bs=1)", &stage1));
 33:   PetscCall(PetscLogEventRegister("VecScatter(bs=1)", PETSC_OBJECT_CLASSID, &event1));
 34:   PetscCall(PetscLogStageRegister("Scatter(bs=4)", &stage2));
 35:   PetscCall(PetscLogEventRegister("VecScatter(bs=4)", PETSC_OBJECT_CLASSID, &event2));

 37:   /* Create a parallel vector x and a sequential vector y */
 38:   PetscCall(VecCreate(PETSC_COMM_WORLD, &x));
 39:   PetscCall(VecSetSizes(x, n, PETSC_DECIDE));
 40:   PetscCall(VecSetFromOptions(x));
 41:   PetscCall(VecGetOwnershipRange(x, &low, &high));
 42:   PetscCall(VecGetSize(x, &N));
 43:   PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &y));

 45:   /*=======================================
 46:      test VecScatter with bs = 1
 47:     ======================================*/

 49:   /* the code works as if we are going to do 3-point stencil computations on a 1D domain x,
 50:      which has periodic boundary conditions but the two ghosts are scatterred to beginning of y.
 51:    */
 52:   bs    = 1;
 53:   ix[0] = rank ? low - 1 : N - 1; /* ix[] contains global indices of the two ghost points */
 54:   ix[1] = (rank != nproc - 1) ? high : 0;
 55:   iy[0] = 0;
 56:   iy[1] = 1;

 58:   PetscCall(ISCreateGeneral(PETSC_COMM_SELF, 2, ix, PETSC_COPY_VALUES, &isx));
 59:   PetscCall(ISCreateGeneral(PETSC_COMM_SELF, 2, iy, PETSC_COPY_VALUES, &isy));
 60:   PetscCall(VecScatterCreate(x, isx, y, isy, &ctx));
 61:   PetscCall(VecScatterSetUp(ctx));

 63:   PetscCall(PetscLogStagePush(stage1));
 64:   PetscCall(PetscLogEventBegin(event1, 0, 0, 0, 0));
 65:   errors = 0;
 66:   for (i = 0; i < niter; i++) {
 67:     /* set x = 0+i, 1+i, 2+i, ..., N-1+i */
 68:     PetscCall(VecGetArray(x, &xval));
 69:     for (j = 0; j < n; j++) xval[j] = (PetscScalar)(low + j + i);
 70:     PetscCall(VecRestoreArray(x, &xval));
 71:     /* scatter the ghosts to y */
 72:     PetscCall(VecScatterBegin(ctx, x, y, INSERT_VALUES, SCATTER_FORWARD));
 73:     PetscCall(VecScatterEnd(ctx, x, y, INSERT_VALUES, SCATTER_FORWARD));
 74:     /* check if y has correct values */
 75:     PetscCall(VecGetArrayRead(y, &yval));
 76:     if ((PetscInt)PetscRealPart(yval[0]) != ix[0] + i) errors++;
 77:     if ((PetscInt)PetscRealPart(yval[1]) != ix[1] + i) errors++;
 78:     PetscCall(VecRestoreArrayRead(y, &yval));
 79:   }
 80:   PetscCall(PetscLogEventEnd(event1, 0, 0, 0, 0));
 81:   PetscCall(PetscLogStagePop());

 83:   /* check if we found wrong values on any processors */
 84:   PetscCall(MPIU_Allreduce(&errors, &tot_errors, 1, MPIU_INT, MPI_SUM, PETSC_COMM_WORLD));
 85:   if (tot_errors) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Error: wrong values were scatterred in vecscatter with bs = %" PetscInt_FMT "\n", bs));

 87:     /* print out event log of VecScatter(bs=1) */
 88: #if defined(PETSC_USE_LOG)
 89:   PetscCall(PetscLogEventGetPerfInfo(stage1, event1, &eventInfo));
 90:   PetscCall(MPIU_Allreduce(&eventInfo.numMessages, &numMessages, 1, MPIU_PETSCLOGDOUBLE, MPI_SUM, PETSC_COMM_WORLD));
 91:   PetscCall(MPIU_Allreduce(&eventInfo.messageLength, &messageLength, 1, MPIU_PETSCLOGDOUBLE, MPI_SUM, PETSC_COMM_WORLD));
 92:   tot_msg = (PetscInt)numMessages * 0.5; /* two MPI calls (Send & Recv) per message */
 93:   tot_len = (PetscInt)messageLength * 0.5;
 94:   avg_len = tot_msg ? (PetscInt)(messageLength / numMessages) : 0;
 95:   /* when nproc > 2, tot_msg = 2*nproc*niter, tot_len = tot_msg*sizeof(PetscScalar)*bs */
 96:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "VecScatter(bs=%" PetscInt_FMT ") has sent out %" PetscInt_FMT " messages, total %" PetscInt_FMT " bytes, with average length %" PetscInt_FMT " bytes\n", bs, tot_msg, tot_len, avg_len));
 97: #endif

 99:   PetscCall(ISDestroy(&isx));
100:   PetscCall(ISDestroy(&isy));
101:   PetscCall(VecScatterDestroy(&ctx));

103:   /*=======================================
104:      test VecScatter with bs = 4
105:     ======================================*/

107:   /* similar to the 3-point stencil above, except that this time a ghost is a block */
108:   bs    = 4;                                /* n needs to be a multiple of bs to make the following code work */
109:   ix[0] = rank ? low / bs - 1 : N / bs - 1; /* ix[] contains global indices of the two ghost blocks */
110:   ix[1] = (rank != nproc - 1) ? high / bs : 0;
111:   iy[0] = 0;
112:   iy[1] = 1;

114:   PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 2, ix, PETSC_COPY_VALUES, &isx));
115:   PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 2, iy, PETSC_COPY_VALUES, &isy));

117:   PetscCall(VecScatterCreate(x, isx, y, isy, &ctx));
118:   /* Call SetUp explicitly, otherwise messages in implicit SetUp will be counted in events below */
119:   PetscCall(VecScatterSetUp(ctx));

121:   PetscCall(PetscLogStagePush(stage2));
122:   PetscCall(PetscLogEventBegin(event2, 0, 0, 0, 0));
123:   errors = 0;
124:   for (i = 0; i < niter; i++) {
125:     /* set x = 0+i, 1+i, 2+i, ..., N-1+i */
126:     PetscCall(VecGetArray(x, &xval));
127:     for (j = 0; j < n; j++) xval[j] = (PetscScalar)(low + j + i);
128:     PetscCall(VecRestoreArray(x, &xval));
129:     /* scatter the ghost blocks to y */
130:     PetscCall(VecScatterBegin(ctx, x, y, INSERT_VALUES, SCATTER_FORWARD));
131:     PetscCall(VecScatterEnd(ctx, x, y, INSERT_VALUES, SCATTER_FORWARD));
132:     /* check if y has correct values */
133:     PetscCall(VecGetArrayRead(y, &yval));
134:     if ((PetscInt)PetscRealPart(yval[0]) != ix[0] * bs + i) errors++;
135:     if ((PetscInt)PetscRealPart(yval[bs]) != ix[1] * bs + i) errors++;
136:     PetscCall(VecRestoreArrayRead(y, &yval));
137:   }
138:   PetscCall(PetscLogEventEnd(event2, 0, 0, 0, 0));
139:   PetscCall(PetscLogStagePop());

141:   /* check if we found wrong values on any processors */
142:   PetscCall(MPIU_Allreduce(&errors, &tot_errors, 1, MPIU_INT, MPI_SUM, PETSC_COMM_WORLD));
143:   if (tot_errors) PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Error: wrong values were scatterred in vecscatter with bs = %" PetscInt_FMT "\n", bs));

145:     /* print out event log of VecScatter(bs=4) */
146: #if defined(PETSC_USE_LOG)
147:   PetscCall(PetscLogEventGetPerfInfo(stage2, event2, &eventInfo));
148:   PetscCall(MPIU_Allreduce(&eventInfo.numMessages, &numMessages, 1, MPIU_PETSCLOGDOUBLE, MPI_SUM, PETSC_COMM_WORLD));
149:   PetscCall(MPIU_Allreduce(&eventInfo.messageLength, &messageLength, 1, MPIU_PETSCLOGDOUBLE, MPI_SUM, PETSC_COMM_WORLD));
150:   tot_msg = (PetscInt)numMessages * 0.5; /* two MPI calls (Send & Recv) per message */
151:   tot_len = (PetscInt)messageLength * 0.5;
152:   avg_len = tot_msg ? (PetscInt)(messageLength / numMessages) : 0;
153:   /* when nproc > 2, tot_msg = 2*nproc*niter, tot_len = tot_msg*sizeof(PetscScalar)*bs */
154:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "VecScatter(bs=%" PetscInt_FMT ") has sent out %" PetscInt_FMT " messages, total %" PetscInt_FMT " bytes, with average length %" PetscInt_FMT " bytes\n", bs, tot_msg, tot_len, avg_len));
155: #endif

157:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Program finished\n"));
158:   PetscCall(ISDestroy(&isx));
159:   PetscCall(ISDestroy(&isy));
160:   PetscCall(VecScatterDestroy(&ctx));
161:   PetscCall(VecDestroy(&x));
162:   PetscCall(VecDestroy(&y));
163:   PetscCall(PetscFinalize());
164:   return 0;
165: }

167: /*TEST

169:    test:
170:       nsize: 4
171:       args:
172:       requires: double defined(PETSC_USE_LOG)

174: TEST*/