This commit is contained in:
Starrick
2025-09-07 14:59:17 +08:00
commit 24dbdbd24b
40 changed files with 10754 additions and 0 deletions
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#undef __CUDA_NO_HALF_OPERATORS__
#undef __CUDA_NO_HALF_CONVERSIONS__
#undef __CUDA_NO_BFLOAT16_CONVERSIONS__
#undef __CUDA_NO_HALF2_OPERATORS__
#include <cuda_runtime.h>
#include <cuda_fp16.h>
#include <cuda_bf16.h>
#include <type_traits>
#include <ATen/cuda/CUDAContext.h>
#include <c10/util/BFloat16.h>
#include <c10/cuda/CUDAStream.h>
#include <torch/extension.h>
// Type traits for CUDA types
template <typename T>
struct CudaTypeTraits
{
static constexpr bool is_supported = false;
};
template <>
struct CudaTypeTraits<float>
{
static constexpr bool is_supported = true;
using type = float;
static constexpr const char *name = "float";
};
template <>
struct CudaTypeTraits<half>
{
static constexpr bool is_supported = true;
using type = half;
static constexpr const char *name = "half";
};
template <>
struct CudaTypeTraits<__nv_bfloat16>
{
static constexpr bool is_supported = true;
using type = __nv_bfloat16;
static constexpr const char *name = "bfloat16";
};
// Optimized forward kernel template
template <typename T>
__global__ void multimodal_rope_forward_kernel(
const T *__restrict__ q, // [batch, q_heads, seq_len, head_dim]
const T *__restrict__ k, // [batch, kv_heads, seq_len, head_dim]
const T *__restrict__ cos, // [3, batch, seq_len, head_dim]
const T *__restrict__ sin, // [3, batch, seq_len, head_dim]
T *__restrict__ q_out, // [batch, q_heads, seq_len, head_dim]
T *__restrict__ k_out, // [batch, kv_heads, seq_len, head_dim]
const int *__restrict__ mrope_section_doubled, // [32, 48, 48]
int batch_size,
int q_heads,
int kv_heads,
int seq_len,
int head_dim)
{
static_assert(CudaTypeTraits<T>::is_supported, "Unsupported data type");
// Block organization: batch_size * (q_heads + kv_heads) blocks
int batch_idx = blockIdx.x;
int head_idx = blockIdx.y;
int seq_paral_size = gridDim.z;
int seq_paral_idx = blockIdx.z;
bool is_q_head = head_idx < q_heads;
int actual_head_idx = is_q_head ? head_idx : (head_idx - q_heads);
int total_heads = is_q_head ? q_heads : kv_heads;
// Each warp processes one token (seq position)
int warp_id = threadIdx.x / 32;
int lane_id = threadIdx.x % 32;
int warps_per_block = blockDim.x / 32;
// Process tokens in batches across warps
for (int seq_base = warp_id + seq_paral_idx * warps_per_block; seq_base < seq_len; seq_base += seq_paral_size * warps_per_block) {
int seq_idx = seq_base;
if (seq_idx >= seq_len)
break;
// Each lane processes multiple dimensions (head_dim=128, 32 lanes)
constexpr int dims_per_lane = 4;
for (int dim_batch = 0; dim_batch < (head_dim + 31) / 32; ++dim_batch)
{
int dim_start = dim_batch * 32 + lane_id;
if (dim_start >= head_dim)
break;
#pragma unroll
for (int dim_offset = 0; dim_offset < dims_per_lane; ++dim_offset)
{
int dim_idx = dim_start + dim_offset * 32;
if (dim_idx >= head_dim)
break;
// Determine which section this dimension belongs to
int section_idx;
int cos_sin_d = dim_idx;
if (dim_idx < mrope_section_doubled[0])
{
section_idx = 0;
}
else if (dim_idx < mrope_section_doubled[0] + mrope_section_doubled[1])
{
section_idx = 1;
}
else
{
section_idx = 2;
}
// Load cos/sin values (coalesced access)
int cos_sin_idx = section_idx * batch_size * seq_len * head_dim +
batch_idx * seq_len * head_dim +
seq_idx * head_dim + cos_sin_d;
T cos_val = cos[cos_sin_idx];
T sin_val = sin[cos_sin_idx];
// Calculate tensor indices
int tensor_idx = batch_idx * total_heads * seq_len * head_dim +
actual_head_idx * seq_len * head_dim +
seq_idx * head_dim + dim_idx;
// Get input value
T input_val = is_q_head ? q[tensor_idx] : k[tensor_idx];
// Calculate rotate_half value
int half_dim = head_dim / 2;
int rotate_dim = (dim_idx < half_dim) ? (dim_idx + half_dim) : (dim_idx - half_dim);
int rotate_tensor_idx = batch_idx * total_heads * seq_len * head_dim +
actual_head_idx * seq_len * head_dim +
seq_idx * head_dim + rotate_dim;
T rotate_val = is_q_head ? q[rotate_tensor_idx] : k[rotate_tensor_idx];
if (dim_idx < half_dim)
{
rotate_val = -rotate_val; // First half: negate second half
}
// Apply RoPE: output = input * cos + rotate_half(input) * sin
T output_val = input_val * cos_val + rotate_val * sin_val;
// Store result
if (is_q_head)
{
q_out[tensor_idx] = output_val;
}
else
{
k_out[tensor_idx] = output_val;
}
}
}
}
}
// Optimized backward kernel template
template <typename T>
__global__ void multimodal_rope_backward_kernel(
const T *__restrict__ grad_q_out, // [batch, q_heads, seq_len, head_dim]
const T *__restrict__ grad_k_out, // [batch, kv_heads, seq_len, head_dim]
const T *__restrict__ q, // [batch, q_heads, seq_len, head_dim]
const T *__restrict__ k, // [batch, kv_heads, seq_len, head_dim]
const T *__restrict__ cos, // [3, batch, seq_len, head_dim]
const T *__restrict__ sin, // [3, batch, seq_len, head_dim]
T *__restrict__ grad_q, // [batch, q_heads, seq_len, head_dim]
T *__restrict__ grad_k, // [batch, kv_heads, seq_len, head_dim]
const int *__restrict__ mrope_section_doubled,
int batch_size,
int q_heads,
int kv_heads,
int seq_len,
int head_dim)
{
int batch_idx = blockIdx.x;
int head_idx = blockIdx.y;
int seq_paral_size = gridDim.z;
int seq_paral_idx = blockIdx.z;
bool is_q_head = head_idx < q_heads;
int actual_head_idx = is_q_head ? head_idx : (head_idx - q_heads);
int total_heads = is_q_head ? q_heads : kv_heads;
int warp_id = threadIdx.x / 32;
int lane_id = threadIdx.x % 32;
int warps_per_block = blockDim.x / 32;
// Process tokens
for (int seq_base = warp_id + seq_paral_idx * warps_per_block; seq_base < seq_len; seq_base += seq_paral_size * warps_per_block)
{
int seq_idx = seq_base;
if (seq_idx >= seq_len)
break;
// Process dimensions in chunks - much simpler now!
constexpr int dims_per_lane = 4;
for (int dim_batch = 0; dim_batch < (head_dim + 31) / 32; ++dim_batch)
{
int dim_start = dim_batch * 32 + lane_id;
if (dim_start >= head_dim)
break;
#pragma unroll
for (int dim_offset = 0; dim_offset < dims_per_lane; ++dim_offset)
{
int dim_idx = dim_start + dim_offset * 32;
if (dim_idx >= head_dim)
break;
// Get section info for cos/sin reconstruction
int section_idx;
int cos_sin_d = dim_idx;
if (dim_idx < mrope_section_doubled[0])
{
section_idx = 0;
}
else if (dim_idx < mrope_section_doubled[0] + mrope_section_doubled[1])
{
section_idx = 1;
}
else
{
section_idx = 2;
}
// Global cos/sin index
int cos_sin_idx = section_idx * batch_size * seq_len * head_dim +
batch_idx * seq_len * head_dim +
seq_idx * head_dim + cos_sin_d;
// Tensor index for current position
int tensor_idx = batch_idx * total_heads * seq_len * head_dim +
actual_head_idx * seq_len * head_dim +
seq_idx * head_dim + dim_idx;
// Load values
T cos_val = cos[cos_sin_idx];
T sin_val = sin[cos_sin_idx];
T grad_out_val = is_q_head ? grad_q_out[tensor_idx] : grad_k_out[tensor_idx];
// Calculate paired dimension for rotate_half
int half_dim = head_dim / 2;
int rotate_dim = (dim_idx < half_dim) ? (dim_idx + half_dim) : (dim_idx - half_dim);
int rotate_tensor_idx = batch_idx * total_heads * seq_len * head_dim +
actual_head_idx * seq_len * head_dim +
seq_idx * head_dim + rotate_dim;
// Get gradient from the paired dimension
T paired_grad_out = is_q_head ? grad_q_out[rotate_tensor_idx] : grad_k_out[rotate_tensor_idx];
// Get paired sin value
int paired_section_idx;
int paired_cos_sin_d = rotate_dim;
if (rotate_dim < mrope_section_doubled[0])
{
paired_section_idx = 0;
}
else if (rotate_dim < mrope_section_doubled[0] + mrope_section_doubled[1])
{
paired_section_idx = 1;
}
else
{
paired_section_idx = 2;
}
int paired_cos_sin_idx = paired_section_idx * batch_size * seq_len * head_dim +
batch_idx * seq_len * head_dim +
seq_idx * head_dim + paired_cos_sin_d;
T paired_sin_val = sin[paired_cos_sin_idx];
// === Compute input gradients (the only thing we need!) ===
// Direct term: grad_input = grad_out * cos
T grad_input_direct = grad_out_val * cos_val;
// Cross term from rotate_half
T grad_input_from_rotate;
if (dim_idx < half_dim)
{
// First half: gets contribution from second half (positive)
grad_input_from_rotate = paired_grad_out * paired_sin_val;
}
else
{
// Second half: gets contribution from first half (negative due to rotate_half)
grad_input_from_rotate = -paired_grad_out * paired_sin_val;
}
// Total input gradient
T total_grad_input = grad_input_direct + grad_input_from_rotate;
// Store input gradients (no atomic operations needed!)
if (is_q_head)
{
grad_q[tensor_idx] = total_grad_input;
}
else
{
grad_k[tensor_idx] = total_grad_input;
}
// No cos/sin gradient computation - they're not learnable parameters!
}
}
}
}
// Template-based host functions
template <typename T>
void launch_multimodal_rope_forward_template(
const T *q, const T *k, const T *cos, const T *sin,
T *q_out, T *k_out,
const int *mrope_section_doubled,
int batch_size, int q_heads, int kv_heads, int seq_len, int head_dim,
cudaStream_t stream)
{
static_assert(CudaTypeTraits<T>::is_supported, "Unsupported data type for multimodal RoPE");
// Grid: batch_size x (q_heads + kv_heads)
dim3 grid(batch_size, q_heads + kv_heads, 8);
// Block: enough threads to handle seq_len with multiple warps
int threads_per_block = min(512, ((seq_len + 3) / 4) * 32); // 4 warps max
threads_per_block = ((threads_per_block + 31) / 32) * 32; // Round to warp size
multimodal_rope_forward_kernel<T><<<grid, threads_per_block, 0, stream>>>(
q, k, cos, sin, q_out, k_out, mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim);
}
template <typename T>
void launch_multimodal_rope_backward_template(
const T *grad_q_out, const T *grad_k_out,
const T *q, const T *k, const T *cos, const T *sin,
T *grad_q, T *grad_k, const int *mrope_section_doubled,
int batch_size, int q_heads, int kv_heads, int seq_len, int head_dim,
cudaStream_t stream)
{
static_assert(CudaTypeTraits<T>::is_supported, "Unsupported data type for multimodal RoPE");
dim3 grid(batch_size, q_heads + kv_heads, 8);
int threads_per_block = min(512, ((seq_len + 3) / 4) * 32);
threads_per_block = ((threads_per_block + 31) / 32) * 32;
multimodal_rope_backward_kernel<T><<<grid, threads_per_block, 0, stream>>>(
grad_q_out, grad_k_out, q, k, cos, sin,
grad_q, grad_k, mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim);
}
// Enum for data type dispatch
enum class DataType
{
FLOAT32,
FLOAT16,
BFLOAT16
};
// Template dispatcher
template <DataType DT>
struct DataTypeDispatcher;
template <>
struct DataTypeDispatcher<DataType::FLOAT32>
{
using type = float;
};
template <>
struct DataTypeDispatcher<DataType::FLOAT16>
{
using type = half;
};
template <>
struct DataTypeDispatcher<DataType::BFLOAT16>
{
using type = __nv_bfloat16;
};
// Type-safe host interface
template <DataType DT>
void launch_multimodal_rope_forward_typed(
const void *q, const void *k, const void *cos, const void *sin,
void *q_out, void *k_out,
const int *mrope_section_doubled,
int batch_size, int q_heads, int kv_heads, int seq_len, int head_dim,
cudaStream_t stream)
{
using T = typename DataTypeDispatcher<DT>::type;
launch_multimodal_rope_forward_template<T>(
static_cast<const T *>(q),
static_cast<const T *>(k),
static_cast<const T *>(cos),
static_cast<const T *>(sin),
static_cast<T *>(q_out),
static_cast<T *>(k_out),
mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim,
stream);
}
template <DataType DT>
void launch_multimodal_rope_backward_typed(
const void *grad_q_out, const void *grad_k_out,
const void *q, const void *k, const void *cos, const void *sin,
void *grad_q, void *grad_k,
const int *mrope_section_doubled,
int batch_size, int q_heads, int kv_heads, int seq_len, int head_dim,
cudaStream_t stream)
{
using T = typename DataTypeDispatcher<DT>::type;
launch_multimodal_rope_backward_template<T>(
static_cast<const T *>(grad_q_out),
static_cast<const T *>(grad_k_out),
static_cast<const T *>(q),
static_cast<const T *>(k),
static_cast<const T *>(cos),
static_cast<const T *>(sin),
static_cast<T *>(grad_q),
static_cast<T *>(grad_k),
mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim,
stream);
}
void launch_multimodal_rope_forward(
torch::Tensor q, torch::Tensor k, torch::Tensor cos, torch::Tensor sin,
torch::Tensor q_out, torch::Tensor k_out,
std::vector<int> mrope_section_doubled)
{
cudaStream_t stream = at::cuda::getCurrentCUDAStream().stream();
int batch_size = q.size(0);
int q_heads = q.size(1);
int seq_len = q.size(2);
int head_dim = q.size(3);
int kv_heads = k.size(1);
int data_type;
if (q.scalar_type() == torch::kFloat32)
{
data_type = 0;
}
else if (q.scalar_type() == torch::kFloat16)
{
data_type = 1;
}
else if (q.scalar_type() == torch::kBFloat16)
{
data_type = 2;
}
int *d_mrope_section_doubled;
cudaMalloc(&d_mrope_section_doubled, 3 * sizeof(int));
cudaMemcpyAsync(d_mrope_section_doubled, mrope_section_doubled.data(), 3 * sizeof(int),
cudaMemcpyHostToDevice, stream);
switch (data_type)
{
case 0: // float32
launch_multimodal_rope_forward_typed<DataType::FLOAT32>(
q.data_ptr(), k.data_ptr(), cos.data_ptr(), sin.data_ptr(),
q_out.data_ptr(), k_out.data_ptr(), d_mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim, stream);
break;
case 1: // float16
launch_multimodal_rope_forward_typed<DataType::FLOAT16>(
q.data_ptr(), k.data_ptr(), cos.data_ptr(), sin.data_ptr(),
q_out.data_ptr(), k_out.data_ptr(), d_mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim, stream);
break;
case 2: // bfloat16
launch_multimodal_rope_forward_typed<DataType::BFLOAT16>(
q.data_ptr(), k.data_ptr(), cos.data_ptr(), sin.data_ptr(),
q_out.data_ptr(), k_out.data_ptr(), d_mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim, stream);
break;
}
}
void launch_multimodal_rope_backward(
torch::Tensor grad_q_out, torch::Tensor grad_k_out,
torch::Tensor q, torch::Tensor k, torch::Tensor cos, torch::Tensor sin,
torch::Tensor grad_q, torch::Tensor grad_k,
std::vector<int> mrope_section_doubled)
{
cudaStream_t stream = at::cuda::getCurrentCUDAStream().stream();
int batch_size = q.size(0);
int q_heads = q.size(1);
int seq_len = q.size(2);
int head_dim = q.size(3);
int kv_heads = k.size(1);
int data_type;
if (q.scalar_type() == torch::kFloat32)
{
data_type = 0;
}
else if (q.scalar_type() == torch::kFloat16)
{
data_type = 1;
}
else if (q.scalar_type() == torch::kBFloat16)
{
data_type = 2;
}
int *d_mrope_section_doubled;
cudaMalloc(&d_mrope_section_doubled, 3 * sizeof(int));
cudaMemcpyAsync(d_mrope_section_doubled, mrope_section_doubled.data(), 3 * sizeof(int),
cudaMemcpyHostToDevice, stream);
switch (data_type)
{
case 0: // float32
launch_multimodal_rope_backward_typed<DataType::FLOAT32>(
grad_q_out.data_ptr(), grad_k_out.data_ptr(),
q.data_ptr(), k.data_ptr(), cos.data_ptr(), sin.data_ptr(),
grad_q.data_ptr(), grad_k.data_ptr(), d_mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim, stream);
break;
case 1: // float16
launch_multimodal_rope_backward_typed<DataType::FLOAT16>(
grad_q_out.data_ptr(), grad_k_out.data_ptr(),
q.data_ptr(), k.data_ptr(), cos.data_ptr(), sin.data_ptr(),
grad_q.data_ptr(), grad_k.data_ptr(), d_mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim, stream);
break;
case 2: // bfloat16
launch_multimodal_rope_backward_typed<DataType::BFLOAT16>(
grad_q_out.data_ptr(), grad_k_out.data_ptr(),
q.data_ptr(), k.data_ptr(), cos.data_ptr(), sin.data_ptr(),
grad_q.data_ptr(), grad_k.data_ptr(), d_mrope_section_doubled,
batch_size, q_heads, kv_heads, seq_len, head_dim, stream);
break;
}
}