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Refactor Kokkos functors to 3D MDRange, remove SIMD specializations, and update Field view #23

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Refactor Kokkos functors to 3D MDRange, remove SIMD specializations, and update Field view #23

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cc529ba
Tune Kokkos shared field view traits for scalar 3D functors
Amazingkivas Mar 8, 2026
55e1e88
Optimize scalar 3D Kokkos functor indexing and wrap logic
Amazingkivas Mar 8, 2026
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264 changes: 49 additions & 215 deletions include/FDTD_kokkos/kokkos_functors.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,8 +25,7 @@ class ComputeE_FieldFunctor : public Base_Functor {
Field &Ex, &Ey, &Ez;
Field &Bx, &By, &Bz;
Field &Jx, &Jy, &Jz;
int start_i, end_i;
int Ni, Nj, Nk;
int Ni, Nj, Nk, Nij;
FP current_coef;
FP coef_dx, coef_dy, coef_dz;

Expand All @@ -36,13 +35,11 @@ class ComputeE_FieldFunctor : public Base_Functor {
Field& Bx, Field& By, Field& Bz,
Field& Jx, Field& Jy, Field& Jz,
const FP& current_coef,
const int& start_i, const int& end_i,
const int& Ni, const int& Nj, const int& Nk,
const FP& coef_dx, const FP& coef_dy, const FP& coef_dz) :
Ex(Ex), Ey(Ey), Ez(Ez), Bx(Bx), By(By), Bz(Bz),
Jx(Jx), Jy(Jy), Jz(Jz), current_coef(current_coef),
start_i(start_i), end_i(end_i),
Ni(Ni), Nj(Nj), Nk(Nk),
Ni(Ni), Nj(Nj), Nk(Nk), Nij(Ni * Nj),
coef_dx(coef_dx), coef_dy(coef_dy), coef_dz(coef_dz) {}

static void apply(
Expand All @@ -52,144 +49,57 @@ class ComputeE_FieldFunctor : public Base_Functor {
const FP& current_coef,
const int bounds_i[2], const int bounds_j[2], const int bounds_k[2],
const int& Ni, const int& Nj, const int& Nk,
const FP& coef_dx, const FP& coef_dy, FP& coef_dz) {
const FP& coef_dx, const FP& coef_dy, const FP& coef_dz) {

ComputeE_FieldFunctor functor(
Ex, Ey, Ez, Bx, By, Bz, Jx, Jy, Jz,
current_coef, bounds_i[0], bounds_i[1],
Ni, Nj, Nk, coef_dx, coef_dy, coef_dz);
current_coef, Ni, Nj, Nk, coef_dx, coef_dy, coef_dz);

Kokkos::MDRangePolicy<Kokkos::Rank<2>> policy(
{bounds_k[0], bounds_j[0]},
{bounds_k[1], bounds_j[1]});
Kokkos::MDRangePolicy<Kokkos::Rank<3, Kokkos::Iterate::Left, Kokkos::Iterate::Right>> policy(
{bounds_k[0], bounds_j[0], bounds_i[0]},
{bounds_k[1], bounds_j[1], bounds_i[1]});

Kokkos::parallel_for("UpdateEField", policy, functor);
}
KOKKOS_INLINE_FUNCTION void operator()(const int& k, const int& j) const {

int j_pred = j - 1;
int k_pred = k - 1;

applyPeriodicBoundary(k_pred, Nk);
applyPeriodicBoundary(j_pred, Nj);

const int index_kj_offset = j * Ni + k * Ni * Nj;
const int j_pred_kj_offset = j_pred * Ni + k * Ni * Nj;
const int k_pred_kj_offset = j * Ni + k_pred * Ni * Nj;

int i_base = start_i;
for (; i_base + simd_width <= end_i; i_base += simd_width) {
const int current_simd_block_start_idx = i_base + index_kj_offset;
const int j_pred_simd_block_start_idx = i_base + j_pred_kj_offset;
const int k_pred_simd_block_start_idx = i_base + k_pred_kj_offset;

simd_type Ex_simd, Ey_simd, Ez_simd;
simd_type Bx_simd, By_simd, Bz_simd;
simd_type Jx_simd, Jy_simd, Jz_simd;
simd_type Bz_pred_simd, Bx_j_pred_simd, By_pred_simd,
Bx_pred_simd, Bz_i_pred_simd, By_i_pred_simd;

Ex_simd.copy_from(Ex.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ey_simd.copy_from(Ey.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ez_simd.copy_from(Ez.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);

Bx_simd.copy_from(Bx.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
By_simd.copy_from(By.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Bz_simd.copy_from(Bz.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);

Jx_simd.copy_from(Jx.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Jy_simd.copy_from(Jy.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Jz_simd.copy_from(Jz.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);

Bz_pred_simd.copy_from(Bz.data() + j_pred_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default); // Bz(i, j-1, k)
Bx_j_pred_simd.copy_from(Bx.data() + j_pred_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default); // Bx(i, j-1, k)
By_pred_simd.copy_from(By.data() + k_pred_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default); // By(i, j, k-1)
Bx_pred_simd.copy_from(Bx.data() + k_pred_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default); // Bx(i, j, k-1)

#pragma unroll
for (int lane = 0; lane < simd_width; ++lane) {
int i = i_base + lane;
int i_pred = i - 1;

applyPeriodicBoundary(i_pred, Ni);

int scalar_i_pred_idx = i_pred + index_kj_offset;

Bz_i_pred_simd[lane] = Bz[scalar_i_pred_idx];
By_i_pred_simd[lane] = By[scalar_i_pred_idx];
}

Ex_simd += current_coef * Jx_simd +
coef_dy * (Bz_simd - Bz_pred_simd) -
coef_dz * (By_simd - By_pred_simd);

Ey_simd += current_coef * Jy_simd +
coef_dz * (Bx_simd - Bx_pred_simd) -
coef_dx * (Bz_simd - Bz_i_pred_simd);

Ez_simd += current_coef * Jz_simd +
coef_dx * (By_simd - By_i_pred_simd) -
coef_dy * (Bx_simd - Bx_j_pred_simd);

Ex_simd.copy_to(Ex.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ey_simd.copy_to(Ey.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ez_simd.copy_to(Ez.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
}
for (int i = i_base; i < end_i; ++i) {
const int index = i + index_kj_offset;
int i_pred = i - 1;

applyPeriodicBoundary(i_pred, Ni);

const int i_pred_idx = i_pred + index_kj_offset;
const int j_pred_idx = i + j_pred_kj_offset;
const int k_pred_idx = i + k_pred_kj_offset;

Ex[index] += current_coef * Jx[index] +
coef_dy * (Bz[index] - Bz[j_pred_idx]) -
coef_dz * (By[index] - By[k_pred_idx]);
Ey[index] += current_coef * Jy[index] +
coef_dz * (Bx[index] - Bx[k_pred_idx]) -
coef_dx * (Bz[index] - Bz[i_pred_idx]);
Ez[index] += current_coef * Jz[index] +
coef_dx * (By[index] - By[i_pred_idx]) -
coef_dy * (Bx[index] - Bx[j_pred_idx]);
}
KOKKOS_INLINE_FUNCTION void operator()(const int& k, const int& j, const int& i) const {

const int j_pred = (j == 0) ? (Nj - 1) : (j - 1);
const int k_pred = (k == 0) ? (Nk - 1) : (k - 1);
const int i_pred = (i == 0) ? (Ni - 1) : (i - 1);

const int jk_offset = j * Ni + k * Nij;
const int index = i + jk_offset;

const int i_pred_idx = i_pred + jk_offset;
const int j_pred_idx = i + j_pred * Ni + k * Nij;
const int k_pred_idx = i + j * Ni + k_pred * Nij;

Ex[index] += current_coef * Jx[index] +
coef_dy * (Bz[index] - Bz[j_pred_idx]) -
coef_dz * (By[index] - By[k_pred_idx]);
Ey[index] += current_coef * Jy[index] +
coef_dz * (Bx[index] - Bx[k_pred_idx]) -
coef_dx * (Bz[index] - Bz[i_pred_idx]);
Ez[index] += current_coef * Jz[index] +
coef_dx * (By[index] - By[i_pred_idx]) -
coef_dy * (Bx[index] - Bx[j_pred_idx]);
}
};

class ComputeB_FieldFunctor : public Base_Functor {
private:
Field &Ex, &Ey, &Ez;
Field &Bx, &By, &Bz;
int Ni, Nj, Nk;
int Ni, Nj, Nk, Nij;
FP coef_dx, coef_dy, coef_dz;
int start_i, end_i;
public:
ComputeB_FieldFunctor(
Field& Ex, Field& Ey, Field& Ez,
Field& Bx, Field& By, Field& Bz,
const int& start_i, const int& end_i,
const int& Ni, const int& Nj, const int& Nk,
const FP& coef_dx, const FP& coef_dy, const FP& coef_dz) :
Ex(Ex), Ey(Ey), Ez(Ez), Bx(Bx), By(By), Bz(Bz),
Ni(Ni), Nj(Nj), Nk(Nk), start_i(start_i), end_i(end_i),
Ni(Ni), Nj(Nj), Nk(Nk), Nij(Ni * Nj),
coef_dx(coef_dx), coef_dy(coef_dy), coef_dz(coef_dz) {}

static void apply(
Expand All @@ -201,110 +111,34 @@ class ComputeB_FieldFunctor : public Base_Functor {

ComputeB_FieldFunctor functor(
Ex, Ey, Ez, Bx, By, Bz,
bounds_i[0], bounds_i[1],
Ni, Nj, Nk, coef_dx, coef_dy, coef_dz);

Kokkos::MDRangePolicy<Kokkos::Rank<2>> policy(
{bounds_k[0], bounds_j[0]},
{bounds_k[1], bounds_j[1]});
Kokkos::MDRangePolicy<Kokkos::Rank<3, Kokkos::Iterate::Left, Kokkos::Iterate::Right>> policy(
{bounds_k[0], bounds_j[0], bounds_i[0]},
{bounds_k[1], bounds_j[1], bounds_i[1]});

Kokkos::parallel_for("UpdateBField", policy, functor);
}
KOKKOS_INLINE_FUNCTION void operator()(const int& k, const int& j) const {
int j_next = j + 1;
int k_next = k + 1;

applyPeriodicBoundary(k_next, Nk);
applyPeriodicBoundary(j_next, Nj);

const int index_kj_offset = j * Ni + k * Ni * Nj;
const int j_next_kj_offset = j_next * Ni + k * Ni * Nj;
const int k_next_kj_offset = j * Ni + k_next * Ni * Nj;

int i_base = start_i;
for (; i_base + simd_width <= end_i; i_base += simd_width) {
const int current_simd_block_start_idx = i_base + index_kj_offset;
const int j_next_simd_block_start_idx = i_base + j_next_kj_offset;
const int k_next_simd_block_start_idx = i_base + k_next_kj_offset;

simd_type Bx_simd, By_simd, Bz_simd;
simd_type Ex_simd, Ey_simd, Ez_simd;
simd_type Ey_k_next_simd, Ex_j_next_simd;
simd_type Ez_i_next_simd, Ey_i_next_simd;
simd_type Ez_j_next_simd, Ex_k_next_simd;

Bx_simd.copy_from(Bx.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
By_simd.copy_from(By.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Bz_simd.copy_from(Bz.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);

Ex_simd.copy_from(Ex.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ey_simd.copy_from(Ey.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ez_simd.copy_from(Ez.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);

Ey_k_next_simd.copy_from(Ey.data() + k_next_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ex_k_next_simd.copy_from(Ex.data() + k_next_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);

Ex_j_next_simd.copy_from(Ex.data() + j_next_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Ez_j_next_simd.copy_from(Ez.data() + j_next_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);

#pragma unroll
for (int lane = 0; lane < simd_width; ++lane) {
int i = i_base + lane;
int i_next = i + 1;
applyPeriodicBoundary(i_next, Ni);

int scalar_i_next_idx = i_next + index_kj_offset;

Ez_i_next_simd[lane] = Ez[scalar_i_next_idx];
Ey_i_next_simd[lane] = Ey[scalar_i_next_idx];
}

Bx_simd += coef_dz * (Ey_k_next_simd - Ey_simd) -
coef_dy * (Ez_j_next_simd - Ez_simd);

By_simd += coef_dx * (Ez_i_next_simd - Ez_simd) -
coef_dz * (Ex_k_next_simd - Ex_simd);

Bz_simd += coef_dy * (Ex_j_next_simd - Ex_simd) -
coef_dx * (Ey_i_next_simd - Ey_simd);

Bx_simd.copy_to(Bx.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
By_simd.copy_to(By.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
Bz_simd.copy_to(Bz.data() + current_simd_block_start_idx,
Kokkos::Experimental::simd_flag_default);
}
KOKKOS_INLINE_FUNCTION void operator()(const int& k, const int& j, const int& i) const {
const int j_next = (j + 1 == Nj) ? 0 : (j + 1);
const int k_next = (k + 1 == Nk) ? 0 : (k + 1);
const int i_next = (i + 1 == Ni) ? 0 : (i + 1);

for (int i = i_base; i < end_i; ++i) {
const int index = i + index_kj_offset;
const int jk_offset = j * Ni + k * Nij;
const int index = i + jk_offset;

int i_next = i + 1;
applyPeriodicBoundary(i_next, Ni);

const int scalar_i_next_idx = i_next + index_kj_offset;
const int scalar_j_next_idx = i + j_next_kj_offset;
const int scalar_k_next_idx = i + k_next_kj_offset;
const int scalar_i_next_idx = i_next + jk_offset;
const int scalar_j_next_idx = i + j_next * Ni + k * Nij;
const int scalar_k_next_idx = i + j * Ni + k_next * Nij;

Bx[index] += coef_dz * (Ey[scalar_k_next_idx] - Ey[index]) -
coef_dy * (Ez[scalar_j_next_idx] - Ez[index]);
Bx[index] += coef_dz * (Ey[scalar_k_next_idx] - Ey[index]) -
coef_dy * (Ez[scalar_j_next_idx] - Ez[index]);

By[index] += coef_dx * (Ez[scalar_i_next_idx] - Ez[index]) -
coef_dz * (Ex[scalar_k_next_idx] - Ex[index]);
By[index] += coef_dx * (Ez[scalar_i_next_idx] - Ez[index]) -
coef_dz * (Ex[scalar_k_next_idx] - Ex[index]);

Bz[index] += coef_dy * (Ex[scalar_j_next_idx] - Ex[index]) -
coef_dx * (Ey[scalar_i_next_idx] - Ey[index]);
}
Bz[index] += coef_dy * (Ex[scalar_j_next_idx] - Ex[index]) -
coef_dx * (Ey[scalar_i_next_idx] - Ey[index]);
}
};

Expand Down
8 changes: 4 additions & 4 deletions include/FDTD_kokkos/kokkos_shared.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,16 +6,16 @@
#include <vector>

#include <Kokkos_Core.hpp>
#include <Kokkos_SIMD.hpp>

#include "Structures.h"


namespace FDTD_kokkos {
using simd_type = Kokkos::Experimental::native_simd<double>;
constexpr int simd_width = int(simd_type::size());
using Device = Kokkos::DefaultExecutionSpace;
using Field = Kokkos::View<double*, Kokkos::MemoryTraits<Kokkos::Aligned>>;
using Field = Kokkos::View<
FP*,
Kokkos::MemoryTraits<Kokkos::Restrict | Kokkos::Aligned>
>;
using TimeField = std::vector<Field>;
using Function = std::function<int(int, int, int)>;
using InitFunction = std::function<double(double, double, double, double)>;
Expand Down