1 static char help[] = "Benchmarking various accessing methods of DMDA vectors on host\n\n"; 2 3 /* 4 On a machine with AMD EPYC-7452 CPUs, we got this data using one MPI rank and a serial-only Kokkos: 5 Time (sec.), on Mar. 1, 2022 6 ------------------------------------------ 7 n PETSc C Kokkos 8 ------------------------------------------ 9 32 4.6464E-05 4.7451E-05 1.6880E-04 10 64 2.5654E-04 2.5164E-04 5.6780E-04 11 128 1.9383E-03 1.8878E-03 4.7938E-03 12 256 1.4450E-02 1.3619E-02 3.7778E-02 13 512 1.1580E-01 1.1551E-01 2.8428E-01 14 1024 1.4179E+00 1.3772E+00 2.2873E+00 15 16 Overall, C is -2% ~ 5% faster than PETSc. But Kokkos is 1.6~3.6x slower than PETSc 17 */ 18 19 #include <petscdmda_kokkos.hpp> 20 #include <petscdm.h> 21 #include <petscdmda.h> 22 23 using Kokkos::Iterate; 24 using Kokkos::MDRangePolicy; 25 using Kokkos::Rank; 26 using PetscScalarKokkosOffsetView3D = Kokkos::Experimental::OffsetView<PetscScalar ***, Kokkos::LayoutRight, Kokkos::HostSpace>; 27 using ConstPetscScalarKokkosOffsetView3D = Kokkos::Experimental::OffsetView<const PetscScalar ***, Kokkos::LayoutRight, Kokkos::HostSpace>; 28 29 /* PETSc multi-dimensional array access */ 30 static PetscErrorCode Update1(DM da, const PetscScalar ***__restrict__ x1, PetscScalar ***__restrict__ y1, PetscInt nwarm, PetscInt nloop, PetscLogDouble *avgTime) { 31 PetscInt it, i, j, k; 32 PetscLogDouble tstart = 0.0, tend; 33 PetscInt xm, ym, zm, xs, ys, zs, gxm, gym, gzm, gxs, gys, gzs; 34 35 PetscFunctionBegin; 36 PetscCall(DMDAGetCorners(da, &xs, &ys, &zs, &xm, &ym, &zm)); 37 PetscCall(DMDAGetGhostCorners(da, &gxs, &gys, &gzs, &gxm, &gym, &gzm)); 38 for (it = 0; it < nwarm + nloop; it++) { 39 if (it == nwarm) PetscCall(PetscTime(&tstart)); 40 for (k = zs; k < zs + zm; k++) { 41 for (j = ys; j < ys + ym; j++) { 42 for (i = xs; i < xs + xm; i++) { y1[k][j][i] = 6 * x1[k][j][i] - x1[k - 1][j][i] - x1[k][j - 1][i] - x1[k][j][i - 1] - x1[k + 1][j][i] - x1[k][j + 1][i] - x1[k][j][i + 1]; } 43 } 44 } 45 } 46 PetscCall(PetscTime(&tend)); 47 *avgTime = (tend - tstart) / nloop; 48 PetscFunctionReturn(0); 49 } 50 51 /* C multi-dimensional array access */ 52 static PetscErrorCode Update2(DM da, const PetscScalar *__restrict__ x2, PetscScalar *__restrict__ y2, PetscInt nwarm, PetscInt nloop, PetscLogDouble *avgTime) { 53 PetscInt it, i, j, k; 54 PetscLogDouble tstart = 0.0, tend; 55 PetscInt xm, ym, zm, xs, ys, zs, gxm, gym, gzm, gxs, gys, gzs; 56 57 PetscFunctionBegin; 58 PetscCall(DMDAGetCorners(da, &xs, &ys, &zs, &xm, &ym, &zm)); 59 PetscCall(DMDAGetGhostCorners(da, &gxs, &gys, &gzs, &gxm, &gym, &gzm)); 60 #define X2(k, j, i) x2[(k - gzs) * gym * gxm + (j - gys) * gxm + (i - gxs)] 61 #define Y2(k, j, i) y2[(k - zs) * ym * xm + (j - ys) * xm + (i - xs)] 62 for (it = 0; it < nwarm + nloop; it++) { 63 if (it == nwarm) PetscCall(PetscTime(&tstart)); 64 for (k = zs; k < zs + zm; k++) { 65 for (j = ys; j < ys + ym; j++) { 66 for (i = xs; i < xs + xm; i++) { Y2(k, j, i) = 6 * X2(k, j, i) - X2(k - 1, j, i) - X2(k, j - 1, i) - X2(k, j, i - 1) - X2(k + 1, j, i) - X2(k, j + 1, i) - X2(k, j, i + 1); } 67 } 68 } 69 } 70 PetscCall(PetscTime(&tend)); 71 *avgTime = (tend - tstart) / nloop; 72 #undef X2 73 #undef Y2 74 PetscFunctionReturn(0); 75 } 76 77 int main(int argc, char **argv) { 78 DM da; 79 PetscInt xm, ym, zm, xs, ys, zs, gxm, gym, gzm, gxs, gys, gzs; 80 PetscInt dof = 1, sw = 1; 81 DMBoundaryType bx = DM_BOUNDARY_PERIODIC, by = DM_BOUNDARY_PERIODIC, bz = DM_BOUNDARY_PERIODIC; 82 DMDAStencilType st = DMDA_STENCIL_STAR; 83 Vec x, y; /* local/global vectors of the da */ 84 PetscRandom rctx; 85 const PetscScalar ***x1; 86 PetscScalar ***y1; /* arrays of g, ll */ 87 const PetscScalar *x2; 88 PetscScalar *y2; 89 ConstPetscScalarKokkosOffsetView3D x3; 90 PetscScalarKokkosOffsetView3D y3; 91 PetscLogDouble tstart = 0.0, tend = 0.0, avgTime = 0.0; 92 PetscInt nwarm = 2, nloop = 10; 93 PetscInt min = 32, max = 32 * 8; /* min and max sizes of the grids to sample */ 94 95 PetscFunctionBeginUser; 96 PetscCall(PetscInitialize(&argc, &argv, (char *)0, help)); 97 PetscCall(PetscRandomCreate(PETSC_COMM_WORLD, &rctx)); 98 PetscCall(PetscOptionsGetInt(NULL, NULL, "-min", &min, NULL)); 99 PetscCall(PetscOptionsGetInt(NULL, NULL, "-max", &max, NULL)); 100 101 for (PetscInt len = min; len <= max; len = len * 2) { 102 PetscCall(DMDACreate3d(PETSC_COMM_WORLD, bx, by, bz, st, len, len, len, PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE, dof, sw, 0, 0, 0, &da)); 103 PetscCall(DMSetFromOptions(da)); 104 PetscCall(DMSetUp(da)); 105 106 PetscCall(DMDAGetCorners(da, &xs, &ys, &zs, &xm, &ym, &zm)); 107 PetscCall(DMDAGetGhostCorners(da, &gxs, &gys, &gzs, &gxm, &gym, &gzm)); 108 PetscCall(DMCreateLocalVector(da, &x)); /* Create local x and global y */ 109 PetscCall(DMCreateGlobalVector(da, &y)); 110 111 /* Access with petsc multi-dimensional arrays */ 112 PetscCall(VecSetRandom(x, rctx)); 113 PetscCall(VecSet(y, 0.0)); 114 PetscCall(DMDAVecGetArrayRead(da, x, &x1)); 115 PetscCall(DMDAVecGetArray(da, y, &y1)); 116 PetscCall(Update1(da, x1, y1, nwarm, nloop, &avgTime)); 117 PetscCall(DMDAVecRestoreArrayRead(da, x, &x1)); 118 PetscCall(DMDAVecRestoreArray(da, y, &y1)); 119 PetscCall(PetscTime(&tend)); 120 PetscCall(PetscPrintf(PETSC_COMM_WORLD, "%4d^3 -- PETSc average time = %e\n", len, avgTime)); 121 122 /* Access with C multi-dimensional arrays */ 123 PetscCall(VecSetRandom(x, rctx)); 124 PetscCall(VecSet(y, 0.0)); 125 PetscCall(VecGetArrayRead(x, &x2)); 126 PetscCall(VecGetArray(y, &y2)); 127 PetscCall(Update2(da, x2, y2, nwarm, nloop, &avgTime)); 128 PetscCall(VecRestoreArrayRead(x, &x2)); 129 PetscCall(VecRestoreArray(y, &y2)); 130 PetscCall(PetscPrintf(PETSC_COMM_WORLD, "%4d^3 -- C average time = %e\n", len, avgTime)); 131 132 /* Access with Kokkos multi-dimensional OffsetViews */ 133 PetscCall(VecSet(y, 0.0)); 134 PetscCall(VecSetRandom(x, rctx)); 135 PetscCall(DMDAVecGetKokkosOffsetView(da, x, &x3)); 136 PetscCall(DMDAVecGetKokkosOffsetView(da, y, &y3)); 137 138 for (PetscInt it = 0; it < nwarm + nloop; it++) { 139 if (it == nwarm) PetscCall(PetscTime(&tstart)); 140 Kokkos::parallel_for( 141 "stencil", MDRangePolicy<Kokkos::DefaultHostExecutionSpace, Rank<3, Iterate::Right, Iterate::Right>>({zs, ys, xs}, {zs + zm, ys + ym, xs + xm}), 142 KOKKOS_LAMBDA(PetscInt k, PetscInt j, PetscInt i) { y3(k, j, i) = 6 * x3(k, j, i) - x3(k - 1, j, i) - x3(k, j - 1, i) - x3(k, j, i - 1) - x3(k + 1, j, i) - x3(k, j + 1, i) - x3(k, j, i + 1); }); 143 } 144 PetscCall(PetscTime(&tend)); 145 PetscCall(DMDAVecRestoreKokkosOffsetView(da, x, &x3)); 146 PetscCall(DMDAVecRestoreKokkosOffsetView(da, y, &y3)); 147 avgTime = (tend - tstart) / nloop; 148 PetscCall(PetscPrintf(PETSC_COMM_WORLD, "%4d^3 -- Kokkos average time = %e\n", len, avgTime)); 149 150 PetscCall(VecDestroy(&x)); 151 PetscCall(VecDestroy(&y)); 152 PetscCall(DMDestroy(&da)); 153 } 154 PetscCall(PetscRandomDestroy(&rctx)); 155 PetscCall(PetscFinalize()); 156 return 0; 157 } 158 159 /*TEST 160 build: 161 requires: kokkos_kernels 162 163 test: 164 suffix: 1 165 requires: kokkos_kernels 166 args: -min 32 -max 32 -dm_vec_type kokkos 167 filter: grep -v "time" 168 169 TEST*/ 170