Date: 2026-05-01T06:12:13+00:00

Actual source code: ex2.c

      1: static const char help[] = "Test overlapped communication on a single star forest (PetscSF)\n\n";

      3: #include <petscvec.h>
      4: #include <petscsf.h>
      5: #include <petscviewer.h>

      7: int main(int argc, char **argv)
      8: {
      9:   PetscSF      sf;
     10:   Vec          A, Aout;
     11:   Vec          B, Bout;
     12:   PetscScalar *bufA;
     13:   PetscScalar *bufAout;
     14:   PetscScalar *bufB;
     15:   PetscScalar *bufBout;
     16:   PetscMPIInt  rank, size;
     17:   PetscInt     nroots, nleaves;
     18:   PetscInt     i;
     19:   PetscInt    *ilocal;
     20:   PetscSFNode *iremote;

     22:   PetscFunctionBeginUser;
     23:   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
     24:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
     25:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));

     27:   PetscCheck(size == 2, PETSC_COMM_WORLD, PETSC_ERR_USER, "Only coded for two MPI processes");

     29:   PetscCall(PetscSFCreate(PETSC_COMM_WORLD, &sf));
     30:   PetscCall(PetscSFSetFromOptions(sf));

     32:   nleaves = 2;
     33:   nroots  = 1;
     34:   PetscCall(PetscMalloc1(nleaves, &ilocal));

     36:   for (i = 0; i < nleaves; i++) ilocal[i] = i;

     38:   PetscCall(PetscMalloc1(nleaves, &iremote));
     39:   if (rank == 0) {
     40:     iremote[0].rank  = 0;
     41:     iremote[0].index = 0;
     42:     iremote[1].rank  = 1;
     43:     iremote[1].index = 0;
     44:   } else {
     45:     iremote[0].rank  = 1;
     46:     iremote[0].index = 0;
     47:     iremote[1].rank  = 0;
     48:     iremote[1].index = 0;
     49:   }
     50:   PetscCall(PetscSFSetGraph(sf, nroots, nleaves, ilocal, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER));
     51:   PetscCall(PetscSFSetUp(sf));
     52:   PetscCall(PetscSFView(sf, PETSC_VIEWER_STDOUT_WORLD));
     53:   PetscCall(VecCreate(PETSC_COMM_WORLD, &A));
     54:   PetscCall(VecSetSizes(A, 2, PETSC_DETERMINE));
     55:   PetscCall(VecSetFromOptions(A));
     56:   PetscCall(VecSetUp(A));

     58:   PetscCall(VecDuplicate(A, &B));
     59:   PetscCall(VecDuplicate(A, &Aout));
     60:   PetscCall(VecDuplicate(A, &Bout));
     61:   PetscCall(VecGetArray(A, &bufA));
     62:   PetscCall(VecGetArray(B, &bufB));
     63:   for (i = 0; i < 2; i++) {
     64:     bufA[i] = (PetscScalar)rank;
     65:     bufB[i] = (PetscScalar)rank + 10.0;
     66:   }
     67:   PetscCall(VecRestoreArray(A, &bufA));
     68:   PetscCall(VecRestoreArray(B, &bufB));

     70:   PetscCall(VecGetArrayRead(A, (const PetscScalar **)&bufA));
     71:   PetscCall(VecGetArrayRead(B, (const PetscScalar **)&bufB));
     72:   PetscCall(VecGetArray(Aout, &bufAout));
     73:   PetscCall(VecGetArray(Bout, &bufBout));
     74:   PetscCall(PetscSFBcastBegin(sf, MPIU_SCALAR, (const void *)bufA, (void *)bufAout, MPI_REPLACE));
     75:   PetscCall(PetscSFBcastBegin(sf, MPIU_SCALAR, (const void *)bufB, (void *)bufBout, MPI_REPLACE));
     76:   PetscCall(PetscSFBcastEnd(sf, MPIU_SCALAR, (const void *)bufA, (void *)bufAout, MPI_REPLACE));
     77:   PetscCall(PetscSFBcastEnd(sf, MPIU_SCALAR, (const void *)bufB, (void *)bufBout, MPI_REPLACE));
     78:   PetscCall(VecRestoreArrayRead(A, (const PetscScalar **)&bufA));
     79:   PetscCall(VecRestoreArrayRead(B, (const PetscScalar **)&bufB));
     80:   PetscCall(VecRestoreArray(Aout, &bufAout));
     81:   PetscCall(VecRestoreArray(Bout, &bufBout));

     83:   PetscCall(VecView(Aout, PETSC_VIEWER_STDOUT_WORLD));
     84:   PetscCall(VecView(Bout, PETSC_VIEWER_STDOUT_WORLD));
     85:   PetscCall(VecDestroy(&A));
     86:   PetscCall(VecDestroy(&B));
     87:   PetscCall(VecDestroy(&Aout));
     88:   PetscCall(VecDestroy(&Bout));
     89:   PetscCall(PetscSFDestroy(&sf));

     91:   PetscCall(PetscFinalize());
     92:   return 0;
     93: }

     95: /*TEST

     97:    test:
     98:       suffix: basic
     99:       nsize: 2
    100:       filter: grep -v "type" | grep -v "sort"
    101:       args: -sf_type basic

    103:    test:
    104:       suffix: window
    105:       nsize: 2
    106:       filter: grep -v "type" | grep -v "sort"
    107:       output_file: output/ex2_basic.out
    108:       args: -sf_type window -sf_window_sync {{fence active lock}} -sf_window_flavor {{create dynamic allocate}}
    109:       requires: defined(PETSC_HAVE_MPI_ONE_SIDED) defined(PETSC_HAVE_MPI_FEATURE_DYNAMIC_WINDOW)

    111:    # The nightly test suite with MPICH uses ch3:sock, which is broken when winsize == 0 in some of the processes
    112:    test:
    113:       suffix: window_shared
    114:       nsize: 2
    115:       filter: grep -v "type" | grep -v "sort"
    116:       output_file: output/ex2_basic.out
    117:       args: -sf_type window -sf_window_sync {{fence active lock}} -sf_window_flavor shared
    118:       requires: defined(PETSC_HAVE_MPI_PROCESS_SHARED_MEMORY) !defined(PETSC_HAVE_MPICH) defined(PETSC_HAVE_MPI_ONE_SIDED)

    120: TEST*/