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/vpbjacobi/vpbjacobi.h> 5 #include <../src/mat/impls/aij/seq/kokkos/aijkok.hpp> // for MatInvertVariableBlockDiagonal_SeqAIJKokkos 6 #include <../src/mat/impls/aij/mpi/mpiaij.h> // for Mat_MPIAIJ 7 #include <KokkosBlas2_gemv.hpp> 8 9 /* A class that manages helper arrays assisting parallel PCApply() with Kokkos */ 10 struct PC_VPBJacobi_Kokkos { 11 /* Cache the old sizes to check if we need realloc */ 12 PetscInt n; /* number of rows of the local matrix */ 13 PetscInt nblocks; /* number of point blocks */ 14 PetscInt nsize; /* sum of sizes (elements) of the point blocks */ 15 16 /* Helper arrays that are pre-computed on host and then copied to device. 17 bs: [nblocks+1], "csr" version of bsizes[] 18 bs2: [nblocks+1], "csr" version of squares of bsizes[] 19 blkMap: [n], row i of the local matrix belongs to the blkMap[i]-th block 20 */ 21 PetscIntKokkosDualView bs_dual, bs2_dual, blkMap_dual; 22 PetscScalarKokkosView diag; // buffer to store diagonal blocks 23 PetscScalarKokkosView work; // work buffer, with the same size as diag[] 24 PetscLogDouble setupFlops; 25 26 // clang-format off 27 // n: size of the matrix 28 // nblocks: number of blocks 29 // nsize: sum bsizes[i]^2 for i=0..nblocks 30 // bsizes[nblocks]: sizes of blocks 31 PC_VPBJacobi_Kokkos(PetscInt n, PetscInt nblocks, PetscInt nsize, const PetscInt *bsizes) : 32 n(n), nblocks(nblocks), nsize(nsize), bs_dual(NoInit("bs_dual"), nblocks + 1), 33 bs2_dual(NoInit("bs2_dual"), nblocks + 1), blkMap_dual(NoInit("blkMap_dual"), n), 34 diag(NoInit("diag"), nsize), work(NoInit("work"), nsize) 35 { 36 PetscCallVoid(BuildHelperArrays(bsizes)); 37 } 38 // clang-format on 39 40 private: 41 PetscErrorCode BuildHelperArrays(const PetscInt *bsizes) 42 { 43 PetscInt *bs_h = bs_dual.view_host().data(); 44 PetscInt *bs2_h = bs2_dual.view_host().data(); 45 PetscInt *blkMap_h = blkMap_dual.view_host().data(); 46 47 PetscFunctionBegin; 48 setupFlops = 0.0; 49 bs_h[0] = bs2_h[0] = 0; 50 for (PetscInt i = 0; i < nblocks; i++) { 51 PetscInt m = bsizes[i]; 52 bs_h[i + 1] = bs_h[i] + m; 53 bs2_h[i + 1] = bs2_h[i] + m * m; 54 for (PetscInt j = 0; j < m; j++) blkMap_h[bs_h[i] + j] = i; 55 // m^3/3 FMA for A=LU factorization; m^3 FMA for solving (LU)X=I to get the inverse 56 setupFlops += 8.0 * m * m * m / 3; 57 } 58 59 PetscCallCXX(bs_dual.modify_host()); 60 PetscCallCXX(bs2_dual.modify_host()); 61 PetscCallCXX(blkMap_dual.modify_host()); 62 PetscCallCXX(bs_dual.sync_device()); 63 PetscCallCXX(bs2_dual.sync_device()); 64 PetscCallCXX(blkMap_dual.sync_device()); 65 PetscCall(PetscLogCpuToGpu(sizeof(PetscInt) * (2 * (nblocks + 1) + n))); 66 PetscFunctionReturn(PETSC_SUCCESS); 67 } 68 }; 69 70 template <PetscBool transpose> 71 static PetscErrorCode PCApplyOrTranspose_VPBJacobi_Kokkos(PC pc, Vec x, Vec y) 72 { 73 PC_VPBJacobi *jac = (PC_VPBJacobi *)pc->data; 74 PC_VPBJacobi_Kokkos *pckok = static_cast<PC_VPBJacobi_Kokkos *>(jac->spptr); 75 ConstPetscScalarKokkosView xv; 76 PetscScalarKokkosView yv; 77 PetscScalarKokkosView diag = pckok->diag; 78 PetscIntKokkosView bs = pckok->bs_dual.view_device(); 79 PetscIntKokkosView bs2 = pckok->bs2_dual.view_device(); 80 PetscIntKokkosView blkMap = pckok->blkMap_dual.view_device(); 81 const char *label = transpose ? "PCApplyTranspose_VPBJacobi" : "PCApply_VPBJacobi"; 82 83 PetscFunctionBegin; 84 PetscCall(PetscLogGpuTimeBegin()); 85 VecErrorIfNotKokkos(x); 86 VecErrorIfNotKokkos(y); 87 PetscCall(VecGetKokkosView(x, &xv)); 88 PetscCall(VecGetKokkosViewWrite(y, &yv)); 89 #if 0 // TODO: Why the TeamGemv version is 2x worse than the naive one? 90 PetscCallCXX(Kokkos::parallel_for( 91 label, Kokkos::TeamPolicy<>(jac->nblocks, Kokkos::AUTO()), KOKKOS_LAMBDA(const KokkosTeamMemberType &team) { 92 PetscInt bid = team.league_rank(); // block id 93 PetscInt n = bs(bid + 1) - bs(bid); // size of this block 94 const PetscScalar *bbuf = &diag(bs2(bid)); 95 const PetscScalar *xbuf = &xv(bs(bid)); 96 PetscScalar *ybuf = &yv(bs(bid)); 97 const auto &B = Kokkos::View<const PetscScalar **, Kokkos::LayoutLeft>(bbuf, n, n); // wrap it in a 2D view in column-major order 98 const auto &x1 = ConstPetscScalarKokkosView(xbuf, n); 99 const auto &y1 = PetscScalarKokkosView(ybuf, n); 100 if (transpose) { 101 KokkosBlas::TeamGemv<KokkosTeamMemberType, KokkosBlas::Trans::Transpose>::invoke(team, 1., B, x1, 0., y1); // y1 = 0.0 * y1 + 1.0 * B^T * x1 102 } else { 103 KokkosBlas::TeamGemv<KokkosTeamMemberType, KokkosBlas::Trans::NoTranspose>::invoke(team, 1., B, x1, 0., y1); // y1 = 0.0 * y1 + 1.0 * B * x1 104 } 105 })); 106 #else 107 PetscCallCXX(Kokkos::parallel_for( 108 label, pckok->n, KOKKOS_LAMBDA(PetscInt row) { 109 const PetscScalar *Bp, *xp; 110 PetscScalar *yp; 111 PetscInt i, j, k, m; 112 113 k = blkMap(row); /* k-th block/matrix */ 114 m = bs(k + 1) - bs(k); /* block size of the k-th block */ 115 i = row - bs(k); /* i-th row of the block */ 116 Bp = &diag(bs2(k) + i * (transpose ? m : 1)); /* Bp points to the first entry of i-th row/column */ 117 xp = &xv(bs(k)); 118 yp = &yv(bs(k)); 119 120 yp[i] = 0.0; 121 for (j = 0; j < m; j++) { 122 yp[i] += Bp[0] * xp[j]; 123 Bp += transpose ? 1 : m; 124 } 125 })); 126 #endif 127 PetscCall(VecRestoreKokkosView(x, &xv)); 128 PetscCall(VecRestoreKokkosViewWrite(y, &yv)); 129 PetscCall(PetscLogGpuFlops(pckok->nsize * 2)); /* FMA on entries in all blocks */ 130 PetscCall(PetscLogGpuTimeEnd()); 131 PetscFunctionReturn(PETSC_SUCCESS); 132 } 133 134 static PetscErrorCode PCDestroy_VPBJacobi_Kokkos(PC pc) 135 { 136 PC_VPBJacobi *jac = (PC_VPBJacobi *)pc->data; 137 138 PetscFunctionBegin; 139 PetscCallCXX(delete static_cast<PC_VPBJacobi_Kokkos *>(jac->spptr)); 140 PetscCall(PCDestroy_VPBJacobi(pc)); 141 PetscFunctionReturn(PETSC_SUCCESS); 142 } 143 144 PETSC_INTERN PetscErrorCode PCSetUp_VPBJacobi_Kokkos(PC pc) 145 { 146 PC_VPBJacobi *jac = (PC_VPBJacobi *)pc->data; 147 PC_VPBJacobi_Kokkos *pckok = static_cast<PC_VPBJacobi_Kokkos *>(jac->spptr); 148 PetscInt i, nlocal, nblocks, nsize = 0; 149 const PetscInt *bsizes; 150 PetscBool ismpi; 151 Mat A; 152 153 PetscFunctionBegin; 154 PetscCall(MatGetVariableBlockSizes(pc->pmat, &nblocks, &bsizes)); 155 PetscCall(MatGetLocalSize(pc->pmat, &nlocal, NULL)); 156 PetscCheck(!nlocal || nblocks, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call MatSetVariableBlockSizes() before using PCVPBJACOBI"); 157 158 if (!jac->diag) { 159 PetscInt max_bs = -1, min_bs = PETSC_MAX_INT; 160 for (i = 0; i < nblocks; i++) { 161 min_bs = PetscMin(min_bs, bsizes[i]); 162 max_bs = PetscMax(max_bs, bsizes[i]); 163 nsize += bsizes[i] * bsizes[i]; 164 } 165 jac->nblocks = nblocks; 166 jac->min_bs = min_bs; 167 jac->max_bs = max_bs; 168 } 169 170 // If one calls MatSetVariableBlockSizes() multiple times and sizes have been changed (is it allowed?), we delete the old and rebuild anyway 171 if (pckok && (pckok->n != nlocal || pckok->nblocks != nblocks || pckok->nsize != nsize)) { 172 PetscCallCXX(delete pckok); 173 pckok = nullptr; 174 } 175 176 PetscCall(PetscLogGpuTimeBegin()); 177 if (!pckok) { 178 PetscCallCXX(pckok = new PC_VPBJacobi_Kokkos(nlocal, nblocks, nsize, bsizes)); 179 jac->spptr = pckok; 180 } 181 182 // Extract diagonal blocks from the matrix and compute their inverse 183 const auto &bs = pckok->bs_dual.view_device(); 184 const auto &bs2 = pckok->bs2_dual.view_device(); 185 const auto &blkMap = pckok->blkMap_dual.view_device(); 186 PetscCall(PetscObjectBaseTypeCompare((PetscObject)pc->pmat, MATMPIAIJ, &ismpi)); 187 A = ismpi ? static_cast<Mat_MPIAIJ *>((pc->pmat)->data)->A : pc->pmat; 188 PetscCall(MatInvertVariableBlockDiagonal_SeqAIJKokkos(A, bs, bs2, blkMap, pckok->work, pckok->diag)); 189 pc->ops->apply = PCApplyOrTranspose_VPBJacobi_Kokkos<PETSC_FALSE>; 190 pc->ops->applytranspose = PCApplyOrTranspose_VPBJacobi_Kokkos<PETSC_TRUE>; 191 pc->ops->destroy = PCDestroy_VPBJacobi_Kokkos; 192 PetscCall(PetscLogGpuTimeEnd()); 193 PetscCall(PetscLogGpuFlops(pckok->setupFlops)); 194 PetscFunctionReturn(PETSC_SUCCESS); 195 } 196