Files
mlx/mlx/backend/cuda/binary_two.cu
Awni Hannun 6441c21a94 Faster general unary op (#2472)
* faster general unary op

* faster general ops + reorg

* fix + comment

* binary two

* copy general
2025-08-15 15:04:12 -07:00

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// Copyright © 2025 Apple Inc.
#include "mlx/backend/common/binary.h"
#include "mlx/backend/cuda/device.h"
#include "mlx/backend/cuda/device/binary_ops.cuh"
#include "mlx/backend/cuda/kernel_utils.cuh"
#include "mlx/dtype_utils.h"
#include "mlx/primitives.h"
#include <cooperative_groups.h>
#include <nvtx3/nvtx3.hpp>
namespace mlx::core {
namespace cu {
namespace cg = cooperative_groups;
template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
__global__ void
binary_two_ss(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
IdxT index = cg::this_grid().thread_rank();
if ((index + 1) * N_READS > size) {
for (IdxT i = index * N_READS; i < size; ++i) {
auto out = Op{}(a[0], b[0]);
out_a[i] = out[0];
out_b[i] = out[1];
}
} else {
AlignedVector<Out, N_READS> out_a_vec;
AlignedVector<Out, N_READS> out_b_vec;
#pragma unroll
for (int i = 0; i < N_READS; ++i) {
auto out = Op{}(a[0], b[0]);
out_a_vec[i] = out[0];
out_b_vec[i] = out[1];
}
store_vector<N_READS>(out_a, index, out_a_vec);
store_vector<N_READS>(out_b, index, out_b_vec);
}
}
template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
__global__ void
binary_two_sv(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
IdxT index = cg::this_grid().thread_rank();
if ((index + 1) * N_READS > size) {
for (IdxT i = index * N_READS; i < size; ++i) {
auto out = Op{}(a[0], b[i]);
out_a[i] = out[0];
out_b[i] = out[1];
}
} else {
auto b_vec = load_vector<N_READS>(b, index);
AlignedVector<Out, N_READS> out_a_vec;
AlignedVector<Out, N_READS> out_b_vec;
#pragma unroll
for (int i = 0; i < N_READS; ++i) {
auto out = Op{}(a[0], b_vec[i]);
out_a_vec[i] = out[0];
out_b_vec[i] = out[1];
}
store_vector<N_READS>(out_a, index, out_a_vec);
store_vector<N_READS>(out_b, index, out_b_vec);
}
}
template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
__global__ void
binary_two_vs(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
IdxT index = cg::this_grid().thread_rank();
if ((index + 1) * N_READS > size) {
for (IdxT i = index * N_READS; i < size; ++i) {
auto out = Op{}(a[i], b[0]);
out_a[i] = out[0];
out_b[i] = out[1];
}
} else {
auto a_vec = load_vector<N_READS>(a, index);
AlignedVector<Out, N_READS> out_a_vec;
AlignedVector<Out, N_READS> out_b_vec;
#pragma unroll
for (int i = 0; i < N_READS; ++i) {
auto out = Op{}(a_vec[i], b[0]);
out_a_vec[i] = out[0];
out_b_vec[i] = out[1];
}
store_vector<N_READS>(out_a, index, out_a_vec);
store_vector<N_READS>(out_b, index, out_b_vec);
}
}
template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
__global__ void
binary_two_vv(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
IdxT index = cg::this_grid().thread_rank();
if ((index + 1) * N_READS > size) {
for (IdxT i = index * N_READS; i < size; ++i) {
auto out = Op{}(a[i], b[i]);
out_a[i] = out[0];
out_b[i] = out[1];
}
} else {
auto a_vec = load_vector<N_READS>(a, index);
auto b_vec = load_vector<N_READS>(b, index);
AlignedVector<Out, N_READS> out_a_vec;
AlignedVector<Out, N_READS> out_b_vec;
#pragma unroll
for (int i = 0; i < N_READS; ++i) {
auto out = Op{}(a_vec[i], b_vec[i]);
out_a_vec[i] = out[0];
out_b_vec[i] = out[1];
}
store_vector<N_READS>(out_a, index, out_a_vec);
store_vector<N_READS>(out_b, index, out_b_vec);
}
}
template <
typename Op,
typename In,
typename Out,
typename IdxT,
int NDIM,
int N_READS>
__global__ void binary_two_g_nd(
const In* a,
const In* b,
Out* out_a,
Out* out_b,
IdxT size_rest,
const __grid_constant__ cuda::std::array<int32_t, NDIM> shape,
const __grid_constant__ cuda::std::array<int64_t, NDIM> a_strides,
const __grid_constant__ cuda::std::array<int64_t, NDIM> b_strides) {
auto block = cg::this_thread_block();
auto grid = cg::this_grid();
IdxT index_rest =
grid.block_index().y * block.dim_threads().y + block.thread_index().y;
if (index_rest >= size_rest) {
return;
}
auto shape_x = shape[NDIM - 1];
auto a_stride_x = a_strides[NDIM - 1];
auto b_stride_x = b_strides[NDIM - 1];
IdxT index_x =
grid.block_index().x * block.dim_threads().x + block.thread_index().x;
auto [a_idx, b_idx] = elem_to_loc_nd<NDIM>(
index_rest * shape_x, shape.data(), a_strides.data(), b_strides.data());
auto a_vec =
load_vector<N_READS>(a + a_idx, index_x, shape_x, a_stride_x, In(0));
auto b_vec =
load_vector<N_READS>(b + b_idx, index_x, shape_x, b_stride_x, In(0));
AlignedVector<Out, N_READS> out_vec_a;
AlignedVector<Out, N_READS> out_vec_b;
#pragma unroll
for (int i = 0; i < N_READS; ++i) {
auto out = Op{}(a_vec[i], b_vec[i]);
out_vec_a[i] = out[0];
out_vec_b[i] = out[1];
}
store_vector(out_a + shape_x * index_rest, index_x, out_vec_a, shape_x);
store_vector(out_b + shape_x * index_rest, index_x, out_vec_b, shape_x);
}
template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
__global__ void binary_two_g(
const In* a,
const In* b,
Out* out_a,
Out* out_b,
IdxT size_rest,
const __grid_constant__ Shape shape,
const __grid_constant__ Strides a_strides,
const __grid_constant__ Strides b_strides,
int ndim) {
auto block = cg::this_thread_block();
auto grid = cg::this_grid();
IdxT index_rest =
grid.block_index().y * block.dim_threads().y + block.thread_index().y;
if (index_rest >= size_rest) {
return;
}
auto shape_x = shape[ndim - 1];
auto a_stride_x = a_strides[ndim - 1];
auto b_stride_x = b_strides[ndim - 1];
IdxT index_x =
grid.block_index().x * block.dim_threads().x + block.thread_index().x;
auto [a_idx, b_idx] = elem_to_loc(
index_rest * shape_x,
shape.data(),
a_strides.data(),
b_strides.data(),
ndim);
auto a_vec =
load_vector<N_READS>(a + a_idx, index_x, shape_x, a_stride_x, In(0));
auto b_vec =
load_vector<N_READS>(b + b_idx, index_x, shape_x, b_stride_x, In(0));
AlignedVector<Out, N_READS> out_vec_a;
AlignedVector<Out, N_READS> out_vec_b;
#pragma unroll
for (int i = 0; i < N_READS; ++i) {
auto out = Op{}(a_vec[i], b_vec[i]);
out_vec_a[i] = out[0];
out_vec_b[i] = out[1];
}
store_vector(out_a + shape_x * index_rest, index_x, out_vec_a, shape_x);
store_vector(out_b + shape_x * index_rest, index_x, out_vec_b, shape_x);
}
template <typename Op, typename In, typename Out>
constexpr bool supports_binary_two_op() {
if (std::is_same_v<Op, DivMod>) {
return std::is_same_v<In, Out> &&
(std::is_integral_v<Out> || is_floating_v<Out>);
}
return false;
}
} // namespace cu
template <typename Op>
void binary_two_op_gpu_inplace(
const std::vector<array>& inputs,
std::vector<array>& outputs,
const char* op,
const Stream& s) {
assert(inputs.size() > 1);
const auto& a = inputs[0];
const auto& b = inputs[1];
auto& out_a = outputs[0];
auto& out_b = outputs[1];
auto bopt = get_binary_op_type(a, b);
set_binary_op_output_data(a, b, out_a, bopt);
set_binary_op_output_data(a, b, out_b, bopt);
if (out_a.size() == 0) {
return;
}
auto& encoder = cu::get_command_encoder(s);
encoder.set_input_array(a);
encoder.set_input_array(b);
encoder.set_output_array(out_a);
encoder.set_output_array(out_b);
dispatch_all_types(a.dtype(), [&](auto in_type_tag) {
dispatch_all_types(out_a.dtype(), [&](auto out_type_tag) {
using CTYPE_IN = MLX_GET_TYPE(in_type_tag);
using CTYPE_OUT = MLX_GET_TYPE(out_type_tag);
if constexpr (cu::supports_binary_two_op<Op, CTYPE_IN, CTYPE_OUT>()) {
using InType = cuda_type_t<CTYPE_IN>;
using OutType = cuda_type_t<CTYPE_OUT>;
auto bopt = get_binary_op_type(a, b);
if (bopt == BinaryOpType::General) {
dispatch_bool(
a.data_size() > INT32_MAX || b.data_size() > INT32_MAX ||
out_a.data_size() > INT32_MAX,
[&](auto large) {
using IdxT = std::conditional_t<large(), int64_t, int32_t>;
Shape shape;
std::vector<Strides> strides;
std::tie(shape, strides) =
collapse_contiguous_dims(a, b, out_a);
auto& a_strides = strides[0];
auto& b_strides = strides[1];
int ndim = shape.size();
int work_per_thread = 1;
auto dim0 = ndim > 0 ? shape.back() : 1;
auto rest = out_a.size() / dim0;
if (dim0 >= 4) {
work_per_thread = 4;
}
dim0 = (dim0 + work_per_thread - 1) / work_per_thread;
auto block_dims = get_block_dims(dim0, rest, 1);
uint32_t num_blocks_x = cuda::ceil_div(dim0, block_dims.x);
uint32_t num_blocks_y = cuda::ceil_div(rest, block_dims.y);
if (ndim <= 3) {
dispatch_1_2_3(ndim, [&](auto dims_constant) {
auto kernel = cu::binary_two_g_nd<
Op,
InType,
OutType,
IdxT,
dims_constant(),
1>;
if (work_per_thread == 4) {
kernel = cu::binary_two_g_nd<
Op,
InType,
OutType,
IdxT,
dims_constant(),
4>;
}
encoder.add_kernel_node(
kernel,
{num_blocks_x, num_blocks_y},
block_dims,
0,
a.data<InType>(),
b.data<InType>(),
out_a.data<OutType>(),
out_b.data<OutType>(),
rest,
const_param<dims_constant()>(shape),
const_param<dims_constant()>(a_strides),
const_param<dims_constant()>(b_strides));
});
} else {
auto kernel = cu::binary_two_g<Op, InType, OutType, IdxT, 1>;
if (work_per_thread == 4) {
kernel = cu::binary_two_g<Op, InType, OutType, IdxT, 4>;
}
encoder.add_kernel_node(
kernel,
{num_blocks_x, num_blocks_y},
block_dims,
0,
a.data<InType>(),
b.data<InType>(),
out_a.data<OutType>(),
out_b.data<OutType>(),
rest,
const_param(shape),
const_param(a_strides),
const_param(b_strides),
ndim);
}
});
} else {
dispatch_bool(out_a.data_size() > UINT32_MAX, [&](auto large) {
using IdxT = std::conditional_t<large(), int64_t, uint32_t>;
constexpr int N_READS = 16 / sizeof(InType);
auto kernel = cu::binary_two_ss<Op, InType, OutType, IdxT, N_READS>;
if (bopt == BinaryOpType::ScalarVector) {
kernel = cu::binary_two_sv<Op, InType, OutType, IdxT, N_READS>;
} else if (bopt == BinaryOpType::VectorScalar) {
kernel = cu::binary_two_vs<Op, InType, OutType, IdxT, N_READS>;
} else if (bopt == BinaryOpType::VectorVector) {
kernel = cu::binary_two_vv<Op, InType, OutType, IdxT, N_READS>;
}
auto [num_blocks, block_dims] = get_launch_args(
out_a.data_size(),
out_a.shape(),
out_a.strides(),
large(),
N_READS);
encoder.add_kernel_node(
kernel,
num_blocks,
block_dims,
0,
a.data<InType>(),
b.data<InType>(),
out_a.data<OutType>(),
out_b.data<OutType>(),
out_a.data_size());
});
}
} else {
throw std::runtime_error(fmt::format(
"Can not do binary op {} on inputs of {} with result of {}.",
op,
dtype_to_string(a.dtype()),
dtype_to_string(out_a.dtype())));
}
});
});
}
template <typename Op>
void binary_two_op_gpu(
const std::vector<array>& inputs,
std::vector<array>& outputs,
const char* op,
const Stream& s) {
auto& a = inputs[0];
auto& b = inputs[1];
auto bopt = get_binary_op_type(a, b);
set_binary_op_output_data(a, b, outputs[0], bopt);
set_binary_op_output_data(a, b, outputs[1], bopt);
binary_two_op_gpu_inplace<Op>(inputs, outputs, op, s);
}
void DivMod::eval_gpu(
const std::vector<array>& inputs,
std::vector<array>& outputs) {
nvtx3::scoped_range r("DivMod::eval_gpu");
auto& s = outputs[0].primitive().stream();
binary_two_op_gpu<cu::DivMod>(inputs, outputs, name(), s);
}
} // namespace mlx::core