vllm/csrc/quantization/fused_kernels/layernorm_utils.cuh

328 lines
12 KiB
Plaintext
Raw Normal View History

#pragma once
/**
* __device__ layernorm utilities.
*/
#include "quantization/vectorization.cuh"
#include "quant_conversions.cuh"
#ifndef USE_ROCM
#include <cub/cub.cuh>
#else
#include <hipcub/hipcub.hpp>
#endif
namespace vllm {
// has_residual must be true, if residual is not a nullptr
template <typename scalar_t, bool has_residual = false>
__device__ void compute_rms(float* rms, scalar_t const* __restrict__ input,
int32_t const hidden_size, float const epsilon,
scalar_t const* __restrict__ residual = nullptr) {
int64_t const token_offset = blockIdx.x * static_cast<int64_t>(hidden_size);
// sum of squares
float ss = 0.0f;
for (int32_t i = threadIdx.x; i < hidden_size; i += blockDim.x) {
float x = static_cast<float>(input[token_offset + i]);
if constexpr (has_residual) {
x += static_cast<float>(residual[token_offset + i]);
}
ss += x * x;
}
using BlockReduce = cub::BlockReduce<float, 1024>;
__shared__ typename BlockReduce::TempStorage reduceStore;
ss = BlockReduce(reduceStore).Reduce(ss, cub::Sum{}, blockDim.x);
__shared__ float s_rms;
if (threadIdx.x == 0) {
s_rms = rsqrtf(ss / hidden_size + epsilon);
}
__syncthreads();
*rms = s_rms;
}
template <typename scalar_t, typename scalar_out_t, bool has_residual = false>
__device__ void compute_dynamic_per_token_scales(
float* __restrict__ token_scale, float* __restrict__ all_token_scales,
scalar_t const* __restrict__ input, scalar_t const* __restrict__ weight,
float const rms, float const* __restrict__ scale_ub,
float const min_scaling_factor, int32_t const hidden_size,
scalar_t const* __restrict__ residual = nullptr) {
int64_t const token_offset = blockIdx.x * static_cast<int64_t>(hidden_size);
;
constexpr scalar_out_t qmax{std::numeric_limits<scalar_out_t>::max()};
float block_absmax_val_maybe = 0.0f;
for (int32_t i = threadIdx.x; i < hidden_size; i += blockDim.x) {
float x = static_cast<float>(input[token_offset + i]);
if constexpr (has_residual) {
x += static_cast<float>(residual[token_offset + i]);
}
x = static_cast<float>(static_cast<scalar_t>(x * rms) * weight[i]);
block_absmax_val_maybe = fmaxf(block_absmax_val_maybe, fabsf(x));
}
using BlockReduce = cub::BlockReduce<float, 1024>;
__shared__ typename BlockReduce::TempStorage reduceStore;
block_absmax_val_maybe =
BlockReduce(reduceStore)
.Reduce(block_absmax_val_maybe, cub::Max{}, blockDim.x);
__shared__ float s_token_scale;
if (threadIdx.x == 0) {
float scale = 0.0f;
if (scale_ub) {
scale = min(block_absmax_val_maybe, *scale_ub);
} else {
scale = block_absmax_val_maybe;
}
// token scale computation
scale = max(scale / qmax, min_scaling_factor);
s_token_scale = scale; // Shared memory store
all_token_scales[blockIdx.x] = scale; // Global output store
}
__syncthreads();
*token_scale = s_token_scale;
}
template <typename scalar_t, typename scalar_out_t, bool is_scale_inverted,
bool has_residual = false>
__device__ void norm_and_quant(scalar_out_t* __restrict__ output,
scalar_t const* __restrict__ input,
scalar_t const* __restrict__ weight,
float const rms, float const scale,
int32_t const hidden_size,
scalar_t* __restrict__ residual = nullptr) {
int64_t const token_offset = blockIdx.x * static_cast<int64_t>(hidden_size);
;
for (int32_t i = threadIdx.x; i < hidden_size; i += blockDim.x) {
float x = static_cast<float>(input[token_offset + i]);
if constexpr (has_residual) {
x += static_cast<float>(residual[token_offset + i]);
residual[token_offset + i] = static_cast<scalar_t>(x);
}
// Norm
x = static_cast<float>(static_cast<scalar_t>(x * rms) * weight[i]);
// Quant
output[token_offset + i] =
ScaledQuant<scalar_out_t, is_scale_inverted>::quant_fn(x, scale);
}
}
namespace vectorized {
// Compute 1.0/rms(input)
// hidden_size must be a multiple of 4
template <typename scalar_t, bool has_residual = false>
__device__ void compute_rms(float* rms, scalar_t const* __restrict__ input,
int32_t const hidden_size, float const epsilon,
scalar_t const* __restrict__ residual = nullptr) {
int64_t const token_offset = blockIdx.x * static_cast<int64_t>(hidden_size);
// Vectorized input/output to better utilize memory bandwidth.
vec4_t<scalar_t> const* vec_input =
reinterpret_cast<vec4_t<scalar_t> const*>(&input[token_offset]);
vec4_t<scalar_t> const* vec_residual = nullptr;
if constexpr (has_residual) {
vec_residual =
reinterpret_cast<vec4_t<scalar_t> const*>(&residual[token_offset]);
}
// sum of squares
float ss = 0.0f;
int32_t const num_vec_elems = hidden_size >> 2;
#pragma unroll 4
for (int32_t i = threadIdx.x; i < num_vec_elems; i += blockDim.x) {
vec4_t<scalar_t> in = vec_input[i];
vec4_t<float> x;
x.x = static_cast<float>(in.x);
x.y = static_cast<float>(in.y);
x.z = static_cast<float>(in.z);
x.w = static_cast<float>(in.w);
if constexpr (has_residual) {
vec4_t<scalar_t> r = vec_residual[i];
x.x += static_cast<float>(r.x);
x.y += static_cast<float>(r.y);
x.z += static_cast<float>(r.z);
x.w += static_cast<float>(r.w);
}
ss += x.x * x.x;
ss += x.y * x.y;
ss += x.z * x.z;
ss += x.w * x.w;
}
using BlockReduce = cub::BlockReduce<float, 1024>;
__shared__ typename BlockReduce::TempStorage reduceStore;
ss = BlockReduce(reduceStore).Reduce(ss, cub::Sum{}, blockDim.x);
__shared__ float s_rms;
if (threadIdx.x == 0) {
s_rms = rsqrtf(ss / hidden_size + epsilon);
}
__syncthreads();
*rms = s_rms;
}
// Vectorized version of vllm::compute_dynamic_per_token_scales
// hidden_size must be a multiple of 4
template <typename scalar_t, typename scalar_out_t, bool has_residual = false>
__device__ void compute_dynamic_per_token_scales(
float* __restrict__ token_scale, float* __restrict__ all_token_scales,
scalar_t const* __restrict__ input, scalar_t const* __restrict__ weight,
float const rms, float const* __restrict__ scale_ub,
float const min_scaling_factor, int32_t const hidden_size,
scalar_t const* __restrict__ residual = nullptr) {
int64_t const token_offset = blockIdx.x * static_cast<int64_t>(hidden_size);
;
// Vectorized input/weight/residual to better utilize memory bandwidth.
vec4_t<scalar_t> const* vec_input =
reinterpret_cast<vec4_t<scalar_t> const*>(&input[token_offset]);
vec4_t<scalar_t> const* vec_weight =
reinterpret_cast<vec4_t<scalar_t> const*>(weight);
vec4_t<scalar_t> const* vec_residual = nullptr;
if constexpr (has_residual) {
vec_residual =
reinterpret_cast<vec4_t<scalar_t> const*>(&residual[token_offset]);
}
constexpr scalar_out_t qmax{std::numeric_limits<scalar_out_t>::max()};
int32_t const num_vec_elems = hidden_size >> 2;
float block_absmax_val_maybe = 0.0f;
#pragma unroll 4
for (int32_t i = threadIdx.x; i < num_vec_elems; i += blockDim.x) {
vec4_t<scalar_t> in = vec_input[i];
vec4_t<scalar_t> const w = vec_weight[i];
vec4_t<float> x;
x.x = static_cast<float>(in.x);
x.y = static_cast<float>(in.y);
x.z = static_cast<float>(in.z);
x.w = static_cast<float>(in.w);
if constexpr (has_residual) {
vec4_t<scalar_t> r = vec_residual[i];
x.x += static_cast<float>(r.x);
x.y += static_cast<float>(r.y);
x.z += static_cast<float>(r.z);
x.w += static_cast<float>(r.w);
}
block_absmax_val_maybe = fmaxf(
block_absmax_val_maybe, fabs(static_cast<scalar_t>(x.x * rms) * w.x));
block_absmax_val_maybe = fmaxf(
block_absmax_val_maybe, fabs(static_cast<scalar_t>(x.y * rms) * w.y));
block_absmax_val_maybe = fmaxf(
block_absmax_val_maybe, fabs(static_cast<scalar_t>(x.z * rms) * w.z));
block_absmax_val_maybe = fmaxf(
block_absmax_val_maybe, fabs(static_cast<scalar_t>(x.w * rms) * w.w));
}
using BlockReduce = cub::BlockReduce<float, 1024>;
__shared__ typename BlockReduce::TempStorage reduceStore;
block_absmax_val_maybe =
BlockReduce(reduceStore)
.Reduce(block_absmax_val_maybe, cub::Max{}, blockDim.x);
__shared__ float s_token_scale;
if (threadIdx.x == 0) {
float scale = 0.0f;
if (scale_ub) {
scale = min(block_absmax_val_maybe, *scale_ub);
} else {
scale = block_absmax_val_maybe;
}
// token scale computation
scale = max(scale / qmax, min_scaling_factor);
s_token_scale = scale; // shared memory store
all_token_scales[blockIdx.x] = scale; // global output store
}
__syncthreads();
*token_scale = s_token_scale;
}
// hidden_size must be a multiple of 4
template <typename scalar_t, typename scalar_out_t, bool is_scale_inverted,
bool has_residual = false>
__device__ void norm_and_quant(scalar_out_t* __restrict__ output,
scalar_t const* __restrict__ input,
scalar_t const* __restrict__ weight,
float const rms, float const scale,
int32_t const hidden_size,
scalar_t* __restrict__ residual = nullptr) {
int64_t const token_offset = blockIdx.x * static_cast<int64_t>(hidden_size);
;
// Vectorized input/output/weight/residual to better utilize memory bandwidth.
vec4_t<scalar_t> const* vec_input =
reinterpret_cast<vec4_t<scalar_t> const*>(&input[token_offset]);
vec4_t<scalar_t> const* vec_weight =
reinterpret_cast<vec4_t<scalar_t> const*>(weight);
q8x4_t<scalar_out_t>* vec_output =
reinterpret_cast<q8x4_t<scalar_out_t>*>(&output[token_offset]);
vec4_t<scalar_t>* vec_residual = nullptr;
if constexpr (has_residual) {
vec_residual = reinterpret_cast<vec4_t<scalar_t>*>(&residual[token_offset]);
}
int32_t const num_vec_elems = hidden_size >> 2;
// TODO(luka/varun) extract into type-agnostic vectorized quant function to
// replace scaled_fp8_conversion_vec
#pragma unroll 4
for (int32_t i = threadIdx.x; i < num_vec_elems; i += blockDim.x) {
vec4_t<scalar_t> const in = vec_input[i];
vec4_t<scalar_t> const w = vec_weight[i];
vec4_t<float> x;
x.x = static_cast<float>(in.x);
x.y = static_cast<float>(in.y);
x.z = static_cast<float>(in.z);
x.w = static_cast<float>(in.w);
if constexpr (has_residual) {
vec4_t<scalar_t> r = vec_residual[i];
x.x += static_cast<float>(r.x);
x.y += static_cast<float>(r.y);
x.z += static_cast<float>(r.z);
x.w += static_cast<float>(r.w);
// Update residual
r.x = static_cast<scalar_t>(x.x);
r.y = static_cast<scalar_t>(x.y);
r.z = static_cast<scalar_t>(x.z);
r.w = static_cast<scalar_t>(x.w);
vec_residual[i] = r;
}
q8x4_t<scalar_out_t> out;
out.x = ScaledQuant<scalar_out_t, is_scale_inverted>::quant_fn(
static_cast<scalar_t>(x.x * rms) * w.x, scale);
out.y = ScaledQuant<scalar_out_t, is_scale_inverted>::quant_fn(
static_cast<scalar_t>(x.y * rms) * w.y, scale);
out.z = ScaledQuant<scalar_out_t, is_scale_inverted>::quant_fn(
static_cast<scalar_t>(x.z * rms) * w.z, scale);
out.w = ScaledQuant<scalar_out_t, is_scale_inverted>::quant_fn(
static_cast<scalar_t>(x.w * rms) * w.w, scale);
vec_output[i] = out;
}
}
} // namespace vectorized
} // namespace vllm