Files
LTX-2/packages/ltx-kernels/csrc/ops/rms_norm_rope.cpp
T
2026-07-07 16:57:50 +00:00

115 lines
4.3 KiB
C++

/******************************************************************************
* Copyright (c) 2023, Tri Dao.
******************************************************************************/
// Host entry point for the fused RMS-norm + RoPE kernel.
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include <torch/extension.h>
#include <vector>
#include "fast_hadamard_transform.h"
#define CHECK_SHAPE(x, ...) TORCH_CHECK(x.sizes() == torch::IntArrayRef({__VA_ARGS__}), #x " must have shape (" #__VA_ARGS__ ")")
template<typename input_t, typename output_t, bool norm_affine>
void rms_norm_rope_cuda(NormRopeHadamardParamsBase &params, cudaStream_t stream);
void set_norm_rope_hadamard_params(NormRopeHadamardParamsBase &params,
// sizes
const size_t batch,
const size_t dim,
const size_t multiple,
// device pointers
const at::Tensor x,
const at::Tensor cos_freqs,
const at::Tensor sin_freqs,
const at::Tensor weights,
const at::Tensor out,
bool norm_affine,
float scale
) {
// Reset the parameters
memset(&params, 0, sizeof(params));
params.batch = batch;
params.dim = dim;
params.log_N = int(ceil(std::log2(dim / multiple)));
// Set the pointers and strides.
params.x_ptr = x.data_ptr();
params.out_ptr = out.data_ptr();
params.cos_freq_ptr = cos_freqs.data_ptr();
params.sin_freq_ptr = sin_freqs.data_ptr();
if (norm_affine){
params.weights_ptr = weights.data_ptr();
} else {
params.weights_ptr = nullptr;
}
// All stride are in elements, not bytes.
params.x_batch_stride = x.stride(0);
params.out_batch_stride = out.stride(0);
params.cos_freq_batch_stride = cos_freqs.stride(0);
params.sin_freq_batch_stride = sin_freqs.stride(0);
params.scale = scale;
}
at::Tensor rms_norm_rope(at::Tensor &x, c10::optional<at::Tensor>& weights_, at::Tensor &cos_freqs, at::Tensor &sin_freqs, bool out_16bit) {
auto input_type = x.scalar_type();
float scale = 1.0f; // :D
TORCH_CHECK(input_type == at::ScalarType::BFloat16);
TORCH_CHECK(x.is_cuda());
const auto shapes_og = x.sizes();
const int dim_og = x.size(-1);
x = x.reshape({-1, dim_og});
if (x.stride(-1) != 1) { x = x.contiguous(); }
const auto sizes = x.sizes();
const int batch_size = sizes[0];
cos_freqs = cos_freqs.reshape({-1, dim_og});
sin_freqs = sin_freqs.reshape({-1, dim_og});
at::Tensor weights;
bool norm_affine = false;
if(weights_.has_value()){
weights = weights_.value();
norm_affine = true;
}
CHECK_SHAPE(x, batch_size, dim_og);
TORCH_CHECK(x.stride(1) == 1);
if (dim_og % 8 != 0) {
x = torch::nn::functional::pad(x, torch::nn::functional::PadFuncOptions({0, 8 - dim_og % 8}));
}
const int dim = x.size(1);
at::Tensor out;
if (out_16bit){
out = torch::empty(x.sizes(), x.options().dtype(torch::kBFloat16));
} else {
out = torch::empty(x.sizes(), x.options().dtype(torch::kFloat8_e4m3fn));
}
at::cuda::CUDAGuard device_guard{(char)x.get_device()};
auto stream = at::cuda::getCurrentCUDAStream().stream();
NormRopeHadamardParamsBase params;
set_norm_rope_hadamard_params(params, batch_size, dim, 1, x, cos_freqs, sin_freqs, weights, out, norm_affine, scale);
TORCH_CHECK(dim % 8 == 0, "fast_hadamard_transform only supports hidden dimension divisible by 8 for now");
TORCH_CHECK(dim <= 32768, "fast_hadamard_transform only supports hidden dimension at most 32768 for now");
if (norm_affine){
if (out_16bit){
rms_norm_rope_cuda<at::BFloat16, at::BFloat16, true>(params, stream);
} else {
rms_norm_rope_cuda<at::BFloat16, at::Float8_e4m3fn, true>(params, stream);
}
} else {
if (out_16bit){
rms_norm_rope_cuda<at::BFloat16, at::BFloat16, false>(params, stream);
} else {
rms_norm_rope_cuda<at::BFloat16, at::Float8_e4m3fn, false>(params, stream);
}
}
return out.reshape(shapes_og);
}