Actual source code: pbjacobi_kok.kokkos.cxx

  1: #include <petscvec_kokkos.hpp>
  2: #include <../src/vec/vec/impls/seq/kokkos/veckokkosimpl.hpp>
  3: #include <petscdevice.h>
  4: #include <../src/ksp/pc/impls/pbjacobi/pbjacobi.h>

  6: struct PC_PBJacobi_Kokkos {
  7:   PetscScalarKokkosDualView diag_dual;

  9:   PC_PBJacobi_Kokkos(PetscInt len, PetscScalar *diag_ptr_h)
 10:   {
 11:     PetscScalarKokkosViewHost diag_h(diag_ptr_h, len);
 12:     auto                      diag_d = Kokkos::create_mirror_view_and_copy(DefaultMemorySpace(), diag_h);
 13:     diag_dual                        = PetscScalarKokkosDualView(diag_d, diag_h);
 14:   }

 16:   PetscErrorCode Update(const PetscScalar *diag_ptr_h)
 17:   {
 18:     PetscFunctionBegin;
 19:     PetscCheck(diag_dual.view_host().data() == diag_ptr_h, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Host pointer has changed since last call");
 20:     PetscCallCXX(diag_dual.modify_host()); /* mark the host has newer data */
 21:     PetscCallCXX(diag_dual.sync_device());
 22:     PetscFunctionReturn(PETSC_SUCCESS);
 23:   }
 24: };

 26: /* Make 'transpose' a template parameter instead of a function input parameter, so that
 27:  it will be a const in template instantiation and gets optimized out.
 28: */
 29: template <PetscBool transpose>
 30: static PetscErrorCode PCApplyOrTranspose_PBJacobi_Kokkos(PC pc, Vec x, Vec y)
 31: {
 32:   PC_PBJacobi               *jac   = (PC_PBJacobi *)pc->data;
 33:   PC_PBJacobi_Kokkos        *pckok = static_cast<PC_PBJacobi_Kokkos *>(jac->spptr);
 34:   ConstPetscScalarKokkosView xv;
 35:   PetscScalarKokkosView      yv;
 36:   PetscScalarKokkosView      Av = pckok->diag_dual.view_device();
 37:   const PetscInt             bs = jac->bs, mbs = jac->mbs, bs2 = bs * bs;
 38:   const char                *label = transpose ? "PCApplyTranspose_PBJacobi_Kokkos" : "PCApply_PBJacobi_Kokkos";

 40:   PetscFunctionBegin;
 41:   PetscCall(PetscLogGpuTimeBegin());
 42:   VecErrorIfNotKokkos(x);
 43:   VecErrorIfNotKokkos(y);
 44:   PetscCall(VecGetKokkosView(x, &xv));
 45:   PetscCall(VecGetKokkosViewWrite(y, &yv));
 46:   PetscCallCXX(Kokkos::parallel_for(
 47:     label, bs * mbs, KOKKOS_LAMBDA(PetscInt row) {
 48:       const PetscScalar *Ap, *xp;
 49:       PetscScalar       *yp;
 50:       PetscInt           i, j, k;

 52:       k  = row / bs;                                /* k-th block */
 53:       i  = row % bs;                                /* this thread deals with i-th row of the block */
 54:       Ap = &Av(bs2 * k + i * (transpose ? bs : 1)); /* Ap points to the first entry of i-th row */
 55:       xp = &xv(bs * k);
 56:       yp = &yv(bs * k);
 57:       /* multiply i-th row (column) with x */
 58:       yp[i] = 0.0;
 59:       for (j = 0; j < bs; j++) {
 60:         yp[i] += Ap[0] * xp[j];
 61:         Ap += (transpose ? 1 : bs); /* block is in column major order */
 62:       }
 63:     }));
 64:   PetscCall(VecRestoreKokkosView(x, &xv));
 65:   PetscCall(VecRestoreKokkosViewWrite(y, &yv));
 66:   PetscCall(PetscLogGpuFlops(bs * bs * mbs * 2)); /* FMA on entries in all blocks */
 67:   PetscCall(PetscLogGpuTimeEnd());
 68:   PetscFunctionReturn(PETSC_SUCCESS);
 69: }

 71: static PetscErrorCode PCDestroy_PBJacobi_Kokkos(PC pc)
 72: {
 73:   PC_PBJacobi *jac = (PC_PBJacobi *)pc->data;

 75:   PetscFunctionBegin;
 76:   PetscCallCXX(delete static_cast<PC_PBJacobi_Kokkos *>(jac->spptr));
 77:   PetscCall(PCDestroy_PBJacobi(pc));
 78:   PetscFunctionReturn(PETSC_SUCCESS);
 79: }

 81: PETSC_INTERN PetscErrorCode PCSetUp_PBJacobi_Kokkos(PC pc)
 82: {
 83:   PC_PBJacobi *jac = (PC_PBJacobi *)pc->data;
 84:   PetscInt     len;

 86:   PetscFunctionBegin;
 87:   PetscCall(PCSetUp_PBJacobi_Host(pc)); /* Compute the inverse on host now. Might worth doing it on device directly */
 88:   len = jac->bs * jac->bs * jac->mbs;
 89:   if (!jac->spptr) {
 90:     PetscCallCXX(jac->spptr = new PC_PBJacobi_Kokkos(len, const_cast<PetscScalar *>(jac->diag)));
 91:   } else {
 92:     PC_PBJacobi_Kokkos *pckok = static_cast<PC_PBJacobi_Kokkos *>(jac->spptr);
 93:     PetscCall(pckok->Update(jac->diag));
 94:   }
 95:   PetscCall(PetscLogCpuToGpu(sizeof(PetscScalar) * len));

 97:   pc->ops->apply          = PCApplyOrTranspose_PBJacobi_Kokkos<PETSC_FALSE>;
 98:   pc->ops->applytranspose = PCApplyOrTranspose_PBJacobi_Kokkos<PETSC_TRUE>;
 99:   pc->ops->destroy        = PCDestroy_PBJacobi_Kokkos;
100:   PetscFunctionReturn(PETSC_SUCCESS);
101: }