TensorRT-LLMs/cpp/tensorrt_llm/kernels/quantization.cuh
hlu1 8207d5fd39
[None] [feat] Add model gpt-oss (#6645)
Signed-off-by: Hao Lu <14827759+hlu1@users.noreply.github.com>
2025-08-07 03:04:18 -04:00

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/*
* Copyright (c) 2019-2023, NVIDIA CORPORATION. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "tensorrt_llm/common/assert.h"
#include "tensorrt_llm/common/cudaTypeUtils.cuh"
#include "tensorrt_llm/common/cudaUtils.h"
#include "tensorrt_llm/common/quantTypeUtils.cuh"
#include "tensorrt_llm/common/reduceKernelUtils.cuh"
#include "tensorrt_llm/kernels/quantization.h"
#include <float.h>
using namespace tensorrt_llm::common;
namespace tensorrt_llm
{
namespace kernels
{
__global__ static void quantizedKernel(char4* dst, float4 const* src, int64_t const sizeDiv4, float const* scalePtr)
{
for (int64_t idx = blockIdx.x * blockDim.x + threadIdx.x; idx < sizeDiv4; idx += blockDim.x * gridDim.x)
{
float const scale = __ldg(scalePtr);
char4 tmp;
float4 const floatTmp = __ldg(src + idx);
tmp.x = cuda_cast<int8_t>(floatTmp.x * scale);
tmp.y = cuda_cast<int8_t>(floatTmp.y * scale);
tmp.z = cuda_cast<int8_t>(floatTmp.z * scale);
tmp.w = cuda_cast<int8_t>(floatTmp.w * scale);
dst[idx] = tmp;
}
}
__global__ static void quantizedKernel(char4* dst, half2 const* src, int64_t const sizeDiv4, float const* scalePtr)
{
for (int64_t idx = blockIdx.x * blockDim.x + threadIdx.x; idx < sizeDiv4; idx += blockDim.x * gridDim.x)
{
float const scale = __ldg(scalePtr);
char4 tmp;
int srcId = idx << 1;
uint2 const h2 = __ldg(reinterpret_cast<uint2 const*>(src + srcId));
half2 const half2Tmp = reinterpret_cast<half2 const&>(h2.x);
half2 const half2Tmp2 = reinterpret_cast<half2 const&>(h2.y);
tmp.x = cuda_cast<int8_t>(cuda_cast<float>(half2Tmp.x) * scale);
tmp.y = cuda_cast<int8_t>(cuda_cast<float>(half2Tmp.y) * scale);
tmp.z = cuda_cast<int8_t>(cuda_cast<float>(half2Tmp2.x) * scale);
tmp.w = cuda_cast<int8_t>(cuda_cast<float>(half2Tmp2.y) * scale);
dst[idx] = tmp;
}
}
#ifdef ENABLE_BF16
__global__ static void quantizedKernel(
char4* dst, __nv_bfloat162 const* src, int64_t const sizeDiv4, float const* scalePtr)
{
for (int64_t idx = blockIdx.x * blockDim.x + threadIdx.x; idx < sizeDiv4; idx += blockDim.x * gridDim.x)
{
float const scale = __ldg(scalePtr);
char4 tmp;
int srcId = idx << 1;
uint2 const h2 = __ldg(reinterpret_cast<uint2 const*>(src + srcId));
__nv_bfloat162 const bfloat162Tmp = reinterpret_cast<__nv_bfloat162 const&>(h2.x);
__nv_bfloat162 const bfloat162Tmp2 = reinterpret_cast<__nv_bfloat162 const&>(h2.y);
tmp.x = cuda_cast<int8_t>(cuda_cast<float>(bfloat162Tmp.x) * scale);
tmp.y = cuda_cast<int8_t>(cuda_cast<float>(bfloat162Tmp.y) * scale);
tmp.z = cuda_cast<int8_t>(cuda_cast<float>(bfloat162Tmp2.x) * scale);
tmp.w = cuda_cast<int8_t>(cuda_cast<float>(bfloat162Tmp2.y) * scale);
dst[idx] = tmp;
}
}
#endif
////////////////////////////////////////////////////////////////////////////////////////////////////
template <typename T, int NUM_ELTS>
struct DstVec
{
static_assert("not implemented.");
};
template <>
struct DstVec<float2, 2>
{
using Type = uint32_t;
};
template <>
struct DstVec<half2, 4>
{
using Type = uint2;
};
#ifdef ENABLE_BF16
template <>
struct DstVec<__nv_bfloat162, 4>
{
using Type = uint2;
};
#endif // ENABLE_BF16
template <typename T>
struct DstVec<T, 4>
{
static_assert(sizeof(T) == 4, "not implemented.");
using Type = uint32_t;
};
template <typename T>
struct DstVec<T, 8>
{
static_assert(sizeof(T) == 2, "not implemented.");
using Type = uint2;
};
////////////////////////////////////////////////////////////////////////////////////////////////////
// Helper function of getting the absMax of all elements in the vector after clamping.
// Pack two elements in order to use possible hmax2 instructions.
template <typename T>
inline __device__ void clampAndAbsMax(T& localMax, uint4& vec, T const clampMin, T const clampMax)
{
static constexpr int NUM_ELTS = sizeof(uint4) / sizeof(T);
#pragma unroll
for (int i = 0; i < NUM_ELTS; ++i)
{
T& val = reinterpret_cast<T*>(&vec)[i];
val = cuda_clamp(val, clampMin, clampMax);
localMax = cuda_max(localMax, cuda_abs(val));
}
}
// Helper function of quantizing the vector and storing it to global memory.
// Pack two elements in order to use fast convert instructions.
template <typename T, typename QuantT, bool USE_SMEM>
inline __device__ void quantizeAndStore(
QuantT* dstPtr, uint4 vec, T const clampMin, T const clampMax, float const scaleOrigQuant)
{
static constexpr int NUM_ELTS = sizeof(uint4) / sizeof(T);
using DstVecType = typename DstVec<T, NUM_ELTS>::Type;
DstVecType dstVec;
#pragma unroll
for (int i = 0; i < NUM_ELTS; ++i)
{
T val = reinterpret_cast<T*>(&vec)[i];
// Values loaded from smem has already been clamped.
if constexpr (!USE_SMEM)
{
val = cuda_clamp(val, clampMin, clampMax);
}
float2 val2 = cuda_cast<float2>(val);
val2.x *= scaleOrigQuant;
val2.y *= scaleOrigQuant;
QuantT quantVal = cuda_cast<QuantT>(val2);
reinterpret_cast<QuantT*>(&dstVec)[i] = quantVal;
}
// Store to destination buffer.
*reinterpret_cast<DstVecType*>(dstPtr) = dstVec;
}
////////////////////////////////////////////////////////////////////////////////////////////////////
template <typename T, typename QuantT, bool USE_SMEM>
__global__ void perTokenQuantization(QuantT* dst, T const* src, int64_t const numRows, int64_t const numCols,
float const* clampPtr, float* scalePtr, float* sumPtr, bool hasFp8MinScaling)
{
// Smem buffer.
extern __shared__ uint4 smemBuffer[];
// The clamping minimum / maximum values.
T const clampMin = cuda_cast<T>(clampPtr ? clampPtr[0] : -FLT_MAX);
T const clampMax = cuda_cast<T>(clampPtr ? clampPtr[1] : FLT_MAX);
// Pack two elements in order to use higher through instructions.
using T2 = typename packed_as<T, 2>::type;
using QuantT2 = typename packed_as<QuantT, 2>::type;
T2 const clampMin2 = cuda_cast<T2, T>(clampMin);
T2 const clampMax2 = cuda_cast<T2, T>(clampMax);
// The quantized data type's maximum value (upper-bound).
static constexpr float MAX_QUANT_VAL = QuantTypeStaticVals<QuantT>::MAX_VAL;
// The minimum scaling factor (lower-bound).
static constexpr float MIN_SCALING_FACTOR = QuantTypeStaticVals<QuantT>::MIN_SCALING_FACTOR;
static constexpr float MIN_SCALING_FACTOR_RCP = QuantTypeStaticVals<QuantT>::MIN_SCALING_FACTOR_RCP;
// The number of elements in the packed uint4 vec.
static constexpr int NUM_ELTS_PER_VEC = sizeof(uint4) / sizeof(T);
static constexpr int NUM_ELTS2_PER_VEC = sizeof(uint4) / sizeof(T2);
// The number of vectors in the column.
int const numColVecs = numCols / NUM_ELTS_PER_VEC;
// The vector pointers for src.
uint4 const* srcVec = reinterpret_cast<uint4 const*>(src) + blockIdx.x * numColVecs;
// The pointer for dst.
QuantT* dstRow = dst + blockIdx.x * numCols;
// T const* srcRow = src + blockIdx.x * numCols;
T2 localMax2 = cuda_cast<T2, T>(T(1e-6f));
float2 localSum2 = {0.f, 0.f};
for (int i = threadIdx.x; i < numColVecs; i += blockDim.x)
{
uint4 vec = srcVec[i];
#pragma unroll
for (int j = 0; j < NUM_ELTS2_PER_VEC; ++j)
{
T2& val2 = reinterpret_cast<T2*>(&vec)[j];
val2 = cuda_clamp(val2, clampMin2, clampMax2);
localMax2 = cuda_max(localMax2, cuda_abs(val2));
// TODO: template the version that requires sum to avoid dynamic branching.
if (sumPtr != nullptr)
{
localSum2.x += cuda_cast<float>(val2.x);
localSum2.y += cuda_cast<float>(val2.y);
}
}
// Avoid reloading from global memory.
if constexpr (USE_SMEM)
{
smemBuffer[i] = vec;
}
}
float const rowMax = blockAllReduceMax(cuda_cast<float>(cuda_max<T, T2>(localMax2)));
if (threadIdx.x == 0)
{
scalePtr[blockIdx.x]
= hasFp8MinScaling ? cuda_max(rowMax / MAX_QUANT_VAL, MIN_SCALING_FACTOR) : (rowMax / MAX_QUANT_VAL);
}
if (sumPtr != nullptr)
{
float rowSum[1] = {cuda_sum<float>(localSum2)};
blockReduceSumV2<float, 1>(rowSum);
if (threadIdx.x == 0)
{
sumPtr[blockIdx.x] = rowSum[0];
}
}
float const scaleOrigQuant
= hasFp8MinScaling ? fminf(MAX_QUANT_VAL / rowMax, MIN_SCALING_FACTOR_RCP) : MAX_QUANT_VAL / rowMax;
for (int i = threadIdx.x; i < numColVecs; i += blockDim.x)
{
uint4 vec = USE_SMEM ? smemBuffer[i] : srcVec[i];
QuantT2* dstPtr = reinterpret_cast<QuantT2*>(dstRow + i * NUM_ELTS_PER_VEC);
quantizeAndStore<T2, QuantT2, USE_SMEM>(dstPtr, vec, clampMin2, clampMax2, scaleOrigQuant);
}
}
////////////////////////////////////////////////////////////////////////////////////////////////////
// FP4/MXFP8 Quantization
constexpr int CVT_ELTS_PER_THREAD = 8;
constexpr int CVT_FP4_THREADS_PER_WARP = 32;
constexpr int CVT_FP8_TO_FP4_ELTS_PER_THREAD = 16;
// Convert 8 float32 values into 8 e2m1 values (represented as one uint32_t).
inline __device__ uint32_t fp32_vec_to_e2m1(float (&array)[8])
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
uint32_t val;
asm volatile(
"{\n"
".reg .b8 byte0;\n"
".reg .b8 byte1;\n"
".reg .b8 byte2;\n"
".reg .b8 byte3;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte0, %2, %1;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte1, %4, %3;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte2, %6, %5;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte3, %8, %7;\n"
"mov.b32 %0, {byte0, byte1, byte2, byte3};\n"
"}"
: "=r"(val)
: "f"(array[0]), "f"(array[1]), "f"(array[2]), "f"(array[3]), "f"(array[4]), "f"(array[5]), "f"(array[6]),
"f"(array[7]));
return val;
#else
// static_assert(false, "not supported.");
return 0;
#endif
}
// Convert 4 float2 values into 8 e2m1 values (represented as one uint32_t).
inline __device__ uint32_t fp32_vec_to_e2m1(float2 (&array)[4])
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
uint32_t val;
asm volatile(
"{\n"
".reg .b8 byte0;\n"
".reg .b8 byte1;\n"
".reg .b8 byte2;\n"
".reg .b8 byte3;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte0, %2, %1;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte1, %4, %3;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte2, %6, %5;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte3, %8, %7;\n"
"mov.b32 %0, {byte0, byte1, byte2, byte3};\n"
"}"
: "=r"(val)
: "f"(array[0].x), "f"(array[0].y), "f"(array[1].x), "f"(array[1].y), "f"(array[2].x), "f"(array[2].y),
"f"(array[3].x), "f"(array[3].y));
return val;
#else
// static_assert(false, "not supported.");
return 0;
#endif
}
// Convert 8 float2 values into 16 e2m1 values (represented as one uint64_t).
inline __device__ uint64_t fp32_vec_to_e2m1(float2 (&array)[8])
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
uint64_t val;
asm volatile(
"{\n"
".reg .b8 byte0;\n"
".reg .b8 byte1;\n"
".reg .b8 byte2;\n"
".reg .b8 byte3;\n"
".reg .b8 byte4;\n"
".reg .b8 byte5;\n"
".reg .b8 byte6;\n"
".reg .b8 byte7;\n"
".reg .b32 val0;\n"
".reg .b32 val1;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte0, %2, %1;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte1, %4, %3;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte2, %6, %5;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte3, %8, %7;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte4, %10, %9;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte5, %12, %11;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte6, %14, %13;\n"
"cvt.rn.satfinite.e2m1x2.f32 byte7, %16, %15;\n"
"mov.b32 val0, {byte0, byte1, byte2, byte3};\n"
"mov.b32 val1, {byte4, byte5, byte6, byte7};\n"
"mov.b64 %0, {val0, val1};\n"
"}"
: "=l"(val)
: "f"(array[0].x), "f"(array[0].y), "f"(array[1].x), "f"(array[1].y), "f"(array[2].x), "f"(array[2].y),
"f"(array[3].x), "f"(array[3].y), "f"(array[4].x), "f"(array[4].y), "f"(array[5].x), "f"(array[5].y),
"f"(array[6].x), "f"(array[6].y), "f"(array[7].x), "f"(array[7].y));
return val;
#else
// static_assert(false, "not supported.");
return 0;
#endif
}
// Convert 4 float2 values into 8 e4m3 values (represented as one uint64_t).
inline __device__ uint64_t fp32_vec_to_e4m3(float2 (&array)[4])
{
union
{
uint64_t val;
__nv_fp8x2_e4m3 elts[4];
} u;
static_assert(sizeof(u.val) == sizeof(u.elts), "Expected to alias uint64_t and __nv_fp8x2_e4m3[4]");
u.elts[0] = __nv_fp8x2_e4m3(array[0]);
u.elts[1] = __nv_fp8x2_e4m3(array[1]);
u.elts[2] = __nv_fp8x2_e4m3(array[2]);
u.elts[3] = __nv_fp8x2_e4m3(array[3]);
return u.val;
}
// Fast reciprocal.
inline __device__ float reciprocal_approximate_ftz(float a)
{
float b;
asm volatile("rcp.approx.ftz.f32 %0, %1;\n" : "=f"(b) : "f"(a));
return b;
}
__device__ __forceinline__ float exp2f_rcp(uint8_t exp)
{
constexpr uint32_t FP32_EXPONENT_BIAS = 127;
return (exp == 0) ? 1 : exp2f(FP32_EXPONENT_BIAS - static_cast<float>(exp));
}
// Define a 16 bytes packed data type.
template <class Type>
struct PackedVec
{
typename TypeConverter<Type>::Type elts[4];
static_assert(sizeof(elts) == sizeof(Type) * CVT_ELTS_PER_THREAD,
"Vector size should match the number of elements per thread.");
};
template <>
struct PackedVec<__nv_fp8_e4m3>
{
__nv_fp8x2_e4m3 elts[8];
static_assert(sizeof(elts) == sizeof(__nv_fp8_e4m3) * CVT_FP8_TO_FP4_ELTS_PER_THREAD,
"Vector size should match the number of elements per thread.");
};
// Quantizes the provided PackedVec into the uint32_t output
template <class Type, int SF_VEC_SIZE, bool UE8M0_SF>
__device__ uint32_t cvt_warp_fp16_to_fp4(PackedVec<Type>& vec, float SFScaleVal, uint8_t* SFout)
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
// Get absolute maximum values among the local 8 values.
auto localMax = cuda_abs(vec.elts[0]);
// Local maximum value.
#pragma unroll
for (int i = 1; i < CVT_ELTS_PER_THREAD / 2; i++)
{
localMax = cuda_max(localMax, cuda_abs(vec.elts[i]));
}
constexpr int CVT_NUM_THREADS_PER_SF = SF_VEC_SIZE / CVT_ELTS_PER_THREAD;
// Get the absolute maximum among all 16 values (two threads for 16, four threads for 32).
localMax = cuda_max(__shfl_xor_sync(uint32_t(-1), localMax, 1), localMax);
if constexpr (CVT_NUM_THREADS_PER_SF == 4)
{
localMax = cuda_max(__shfl_xor_sync(uint32_t(-1), localMax, 2), localMax);
}
// Get the final absolute maximum values.
float vecMax = float(cuda_max(localMax.x, localMax.y));
// 8 bits representation of the SF.
uint8_t fp8SFVal;
float outputScale;
// Write the SF to global memory (STG.8).
if constexpr (UE8M0_SF)
{
__nv_fp8_e8m0 tmp;
// Scale the max value to the range of E2m1.
vecMax *= reciprocal_approximate_ftz(6.0f);
tmp.__x = __nv_cvt_float_to_e8m0(vecMax, __NV_SATFINITE, cudaRoundPosInf);
fp8SFVal = tmp.__x;
outputScale = vecMax != 0 ? exp2f_rcp(fp8SFVal) : 0.0f;
}
else
{
// Get the SF (max value of the vector / max value of e2m1).
// maximum value of e2m1 = 6.0.
// TODO: use half as compute data type.
auto SFValue = SFScaleVal * (vecMax * reciprocal_approximate_ftz(6.0f));
// Here SFValue is always positive, so E4M3 is the same as UE4M3.
__nv_fp8_e4m3 tmp = __nv_fp8_e4m3(SFValue);
fp8SFVal = tmp.__x;
SFValue = static_cast<float>(tmp);
// Get the output scale.
// Recipe: final_scale = reciprocal(fp32(fp8(SFValue * SFScaleVal)) * reciprocal(SFScaleVal))
outputScale = vecMax != 0 ? reciprocal_approximate_ftz(SFValue * reciprocal_approximate_ftz(SFScaleVal)) : 0.0f;
}
if (SFout)
{
// Write the SF to global memory (STG.8).
*SFout = fp8SFVal;
}
// Convert the input to float.
float2 fp2Vals[CVT_ELTS_PER_THREAD / 2];
#pragma unroll
for (int i = 0; i < CVT_ELTS_PER_THREAD / 2; i++)
{
if constexpr (std::is_same_v<Type, half>)
{
fp2Vals[i] = __half22float2(vec.elts[i]);
}
else
{
fp2Vals[i] = __bfloat1622float2(vec.elts[i]);
}
fp2Vals[i].x *= outputScale;
fp2Vals[i].y *= outputScale;
}
// Convert to e2m1 values.
uint32_t e2m1Vec = fp32_vec_to_e2m1(fp2Vals);
// Write the e2m1 values to global memory.
return e2m1Vec;
#else
return 0;
#endif
}
template <class Type, int SF_VEC_SIZE, bool UE8M0_SF>
__device__ uint64_t cvt_warp_fp8_to_fp4(PackedVec<Type>& vec, float SFScaleVal, uint8_t* SFout)
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
float const dequant_to_fp16_scale = 6.f * reciprocal_approximate_ftz(SFScaleVal);
// Dequant fp8 to fp16
__half2 vec_half2[8];
#pragma unroll
for (int i = 0; i < CVT_FP8_TO_FP4_ELTS_PER_THREAD / 2; i++)
{
float2 tmp = static_cast<float2>(vec.elts[i]);
tmp.x *= dequant_to_fp16_scale;
tmp.y *= dequant_to_fp16_scale;
vec_half2[i] = __float22half2_rn(tmp);
}
// Get absolute maximum values among the local 8 values.
auto localMax = __habs2(vec_half2[0]);
// Local maximum value.
#pragma unroll
for (int i = 1; i < CVT_FP8_TO_FP4_ELTS_PER_THREAD / 2; i++)
{
localMax = __hmax2(localMax, __habs2(vec_half2[i]));
}
constexpr int CVT_NUM_THREADS_PER_SF = SF_VEC_SIZE / CVT_FP8_TO_FP4_ELTS_PER_THREAD;
if constexpr (CVT_NUM_THREADS_PER_SF == 2)
{
// For block 32, we need to reduce the local max across two threads.
localMax = __hmax2(__shfl_xor_sync(uint32_t(-1), localMax, 1), localMax);
}
// Get the final absolute maximum values.
float vecMax = float(__hmax(localMax.x, localMax.y));
// Get the SF (max value of the vector / max value of e2m1).
// maximum value of e2m1 = 6.0.
// TODO: use half as compute data type.
float SFValue = SFScaleVal * (vecMax * reciprocal_approximate_ftz(6.0f));
float SFValueNarrow;
// 8 bits representation of the SF.
uint8_t fp8SFVal;
// Write the SF to global memory (STG.8).
if constexpr (UE8M0_SF)
{
__nv_fp8_e8m0 tmp;
tmp.__x = __nv_cvt_float_to_e8m0(SFValue, __NV_SATFINITE, cudaRoundPosInf);
SFValueNarrow = static_cast<float>(tmp);
fp8SFVal = tmp.__x;
}
else
{
// Here SFValue is always positive, so E4M3 is the same as UE4M3.
__nv_fp8_e4m3 tmp = __nv_fp8_e4m3(SFValue);
fp8SFVal = tmp.__x;
SFValueNarrow = static_cast<float>(tmp);
}
// Get the output scale.
// Recipe: final_scale = reciprocal(fp32(fp8(SFValue * SFScaleVal))) * reciprocal(SFScaleVal))
float outputScale = SFValue != 0 ? SFScaleVal * reciprocal_approximate_ftz(SFValueNarrow) : 0.0f;
if (SFout)
{
// Write the SF to global memory (STG.8).
*SFout = fp8SFVal;
}
// Convert the input to float.
float2 fp2Vals[CVT_FP8_TO_FP4_ELTS_PER_THREAD / 2];
#pragma unroll
for (int i = 0; i < CVT_FP8_TO_FP4_ELTS_PER_THREAD / 2; i++)
{
fp2Vals[i] = __half22float2(vec_half2[i]);
fp2Vals[i].x *= outputScale;
fp2Vals[i].y *= outputScale;
}
// Convert to e2m1 values.
uint64_t e2m1Vec = fp32_vec_to_e2m1(fp2Vals);
// Write the e2m1 values to global memory.
return e2m1Vec;
#else
return 0;
#endif
}
// Quantizes the provided PackedVec into the uint64_t output
template <class Type, int SF_VEC_SIZE>
__device__ uint64_t cvt_warp_fp16_to_mxfp8(PackedVec<Type>& vec, uint8_t* SFout)
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
// Get absolute maximum values among the local 8 values.
auto localMax = cuda_abs(vec.elts[0]);
// Local maximum value.
#pragma unroll
for (int i = 1; i < CVT_ELTS_PER_THREAD / 2; i++)
{
localMax = cuda_max(localMax, cuda_abs(vec.elts[i]));
}
constexpr int CVT_NUM_THREADS_PER_SF = SF_VEC_SIZE / CVT_ELTS_PER_THREAD;
// Get the absolute maximum among all 16 values (two threads for 16, four threads for 32).
localMax = cuda_max(__shfl_xor_sync(uint32_t(-1), localMax, 1), localMax);
if constexpr (CVT_NUM_THREADS_PER_SF == 4)
{
localMax = cuda_max(__shfl_xor_sync(uint32_t(-1), localMax, 2), localMax);
}
// Get the final absolute maximum values.
float vecMax = float(cuda_max(localMax.x, localMax.y));
// Get the SF (max value of the vector / max value of mxfp8).
float SFValue = vecMax * reciprocal_approximate_ftz(448.0f);
// 8 bits representation of the SF.
uint8_t fp8SFVal;
// Write the SF to global memory (STG.8).
__nv_fp8_e8m0 tmpSFVal;
tmpSFVal.__x = __nv_cvt_float_to_e8m0(SFValue, __NV_SATFINITE, cudaRoundPosInf);
SFValue = static_cast<float>(tmpSFVal);
fp8SFVal = tmpSFVal.__x;
// Get the output scale (reciprocal of the SFValue).
float outputScale = vecMax != 0.f ? reciprocal_approximate_ftz(SFValue) : 0.0f;
if (SFout)
{
// Write the SF to global memory (STG.8).
*SFout = fp8SFVal;
}
// Convert the input to float.
float2 fp2Vals[CVT_ELTS_PER_THREAD / 2];
#pragma unroll
for (int i = 0; i < CVT_ELTS_PER_THREAD / 2; i++)
{
if constexpr (std::is_same_v<Type, half>)
{
fp2Vals[i] = __half22float2(vec.elts[i]);
}
else
{
fp2Vals[i] = __bfloat1622float2(vec.elts[i]);
}
fp2Vals[i].x *= outputScale;
fp2Vals[i].y *= outputScale;
}
// Convert to e4m3 values.
uint64_t e4m3Vec = fp32_vec_to_e4m3(fp2Vals);
// Write the e4m3 values to global memory.
return e4m3Vec;
#else
return 0;
#endif
}
inline __host__ __device__ int64_t get_sf_out_offset_128x4(
std::optional<int> batchIdx, int mIdx, int kIdx, std::optional<int> numRows, int numColVecs)
{
// SF layout [numMTiles, numKTiles, 32 (mTile), 4 (mTile), 4(kTile)]
// --> index [mTileIdx, kTileIdx, outerMIdx, innerMIdx, innerKIdx]
// batched tensor
// SF layout [numBTiles, numMTiles, numKTiles, 32 (mTile), 4 (mTile), 4(kTile)]
// --> index [bTileIdx, mTileIdx, kTileIdx, outerMIdx, innerMIdx, innerKIdx]
int32_t innerKIdx = (kIdx % 4);
int64_t innerKStride = 1;
int32_t innerMIdx = (mIdx % (32 * 4)) / 32;
int64_t innerMStride = 4 * innerKStride; // 4
// M tile layout [32, 4] is column-major.
int32_t outerMIdx = (mIdx % 32);
int64_t outerMStride = 4 * innerMStride; // 16
int32_t kTileIdx = (kIdx / 4);
int64_t kTileStride = 32 * outerMStride; // 512
// SF vector size 16 or 32. We round the "numCols" up to a multiple of 64 or 128.
// It is the same as rounding the "numColVecs" up to a multiple of 4.
int32_t numKTiles = (numColVecs + 4 - 1) / 4;
int32_t mTileIdx = mIdx / (32 * 4);
int64_t mTileStride = numKTiles * kTileStride;
// Each SF block has 128 rows so pad rows to the multiple of 128.
int32_t numMTiles = (numRows.value_or(0) + 128 - 1) / 128;
int64_t bTileStride = numMTiles * mTileStride;
// Compute the global offset.
int64_t SFOffset = batchIdx.value_or(0) * bTileStride + mTileIdx * mTileStride + kTileIdx * kTileStride
+ outerMIdx * outerMStride + innerMIdx * innerMStride + innerKIdx * innerKStride;
return SFOffset;
}
template <class SFType, int CVT_NUM_THREADS_PER_SF>
__device__ uint8_t* cvt_quant_get_sf_out_offset(std::optional<int> batchIdx, int rowIdx, int colVecIdx,
std::optional<int> numRows, int numColVecs, SFType* SFout, QuantizationSFLayout layout)
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
// Each thread holds one vector.
static_assert(CVT_NUM_THREADS_PER_SF == 1 || CVT_NUM_THREADS_PER_SF == 2 || CVT_NUM_THREADS_PER_SF == 4);
// One pair of threads write one SF to global memory.
// TODO: stage through smem for packed STG.32
// is it better than STG.8 from 4 threads ?
if (threadIdx.x % CVT_NUM_THREADS_PER_SF == 0)
{
if (layout == QuantizationSFLayout::SWIZZLED)
{
// SF vector index (16 elements share one SF in the K dimension).
// numRows and numCols are unpadded.
int32_t kIdx = colVecIdx / CVT_NUM_THREADS_PER_SF;
int32_t mIdx = rowIdx;
auto SFOffset = get_sf_out_offset_128x4(batchIdx, mIdx, kIdx, numRows, numColVecs);
return reinterpret_cast<uint8_t*>(SFout) + SFOffset;
}
else if (layout == QuantizationSFLayout::LINEAR)
{
// Linear row-major layout, no padding required.
int32_t KTileIdx = colVecIdx / CVT_NUM_THREADS_PER_SF;
int32_t numKTiles = numColVecs;
int64_t mTileStride = numKTiles;
int64_t BTileStride = numRows.value_or(0) * mTileStride;
int64_t SFOffset = batchIdx.value_or(0) * BTileStride + rowIdx * mTileStride + KTileIdx;
return reinterpret_cast<uint8_t*>(SFout) + SFOffset;
}
else
{
return nullptr;
}
}
#endif
return nullptr;
}
template <BlockScaleQuantizationType quantization_type, class Type, int SF_VEC_SIZE, bool UE8M0_SF>
__global__ void
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
__launch_bounds__(512, 4) quantize_with_block_size(
#else
quantize_with_block_size(
#endif
int32_t numbatches, int32_t numRows, int32_t numCols, int32_t numPaddedCols, Type const* in,
float const* SFScale, uint32_t* out, uint32_t* SFout, QuantizationSFLayout layout)
{
#if defined(__CUDA_ARCH__) && (__CUDA_ARCH__ >= 1000)
// The elements per thread.
static constexpr int ELTS_PER_THREAD = quantization_type == BlockScaleQuantizationType::FP8_TO_FP4
? CVT_FP8_TO_FP4_ELTS_PER_THREAD
: CVT_ELTS_PER_THREAD;
using PackedVec = PackedVec<Type>;
static constexpr int CVT_NUM_THREADS_PER_SF = SF_VEC_SIZE / ELTS_PER_THREAD; // 2 or 4
static_assert(sizeof(PackedVec) == sizeof(Type) * ELTS_PER_THREAD, "Vec size is not matched.");
// Get the global scaling factor, which will be applied to the SF.
// Note SFScale is the same as next GEMM's alpha, which is (448.f / (Alpha_A / 6.f)).
float const SFScaleVal = SFScale == nullptr ? 1.0f : SFScale[0];
// Is it swizzled layout?
bool isSfSwizzledLayout = layout == QuantizationSFLayout::SWIZZLED;
// The number of padded rows considering 128x4 SF layout.
int numPaddedRowsForSf = isSfSwizzledLayout ? PadUpFn(numRows, 128) : numRows;
int numColsForSf = isSfSwizzledLayout ? PadUpFn(numPaddedCols, 4 * SF_VEC_SIZE) : numPaddedCols;
// The number of threads in the column dimension。
// Note that numCols/numPaddedCols/numColsForSf are guaranteed to be multiples of ELTS_PER_THREAD.
int numColThreads = numCols / ELTS_PER_THREAD;
int numPaddedColThreads = numPaddedCols / ELTS_PER_THREAD;
int numColThreadsForSf = numColsForSf / ELTS_PER_THREAD;
asm volatile("griddepcontrol.wait;");
// Input tensor batch/row/col loops.
for (int rowIdx = blockIdx.x; rowIdx < numPaddedRowsForSf; rowIdx += gridDim.x)
{
for (int batchIdx = 0; batchIdx < numbatches; batchIdx++)
{
for (int colIdx = threadIdx.x; colIdx < numColThreadsForSf; colIdx += blockDim.x)
{
std::optional<int> optionalBatchIdx = batchIdx;
std::optional<int> optionalNumRows = numRows;
// The SF output pointer.
auto sf_out = cvt_quant_get_sf_out_offset<uint32_t, CVT_NUM_THREADS_PER_SF>(
optionalBatchIdx, rowIdx, colIdx, optionalNumRows, numPaddedCols / SF_VEC_SIZE, SFout, layout);
// The input tensor offset.
int64_t inOffset = static_cast<int64_t>(batchIdx * numRows + rowIdx) * numColThreads + colIdx;
int64_t outOffset = static_cast<int64_t>(batchIdx * numRows + rowIdx) * numPaddedColThreads + colIdx;
// Set the values to 0 of those are padded columns.
if (rowIdx < numRows && colIdx >= numColThreads && colIdx < numPaddedColThreads)
{
// Dispatch the quantization kernel.
if constexpr (quantization_type == BlockScaleQuantizationType::FP16_TO_FP4)
{
reinterpret_cast<uint32_t*>(out)[outOffset] = 0u;
}
else if constexpr (quantization_type == BlockScaleQuantizationType::FP8_TO_FP4
|| quantization_type == BlockScaleQuantizationType::FP16_TO_MXFP8)
{
reinterpret_cast<uint64_t*>(out)[outOffset] = 0ull;
}
}
// Set the SF padding to 0.
if (rowIdx >= numRows || colIdx >= numColThreads)
{
// Set the SF padding to 0.
if (sf_out != nullptr)
{
sf_out[0] = 0x00;
}
}
else
{
// Load the input vector.
PackedVec in_vec = reinterpret_cast<PackedVec const*>(in)[inOffset];
// Dispatch the quantization kernel.
if constexpr (quantization_type == BlockScaleQuantizationType::FP16_TO_FP4)
{
reinterpret_cast<uint32_t*>(out)[outOffset]
= cvt_warp_fp16_to_fp4<Type, SF_VEC_SIZE, UE8M0_SF>(in_vec, SFScaleVal, sf_out);
}
else if constexpr (quantization_type == BlockScaleQuantizationType::FP8_TO_FP4)
{
reinterpret_cast<uint64_t*>(out)[outOffset]
= cvt_warp_fp8_to_fp4<__nv_fp8_e4m3, SF_VEC_SIZE, UE8M0_SF>(in_vec, SFScaleVal, sf_out);
}
else if constexpr (quantization_type == BlockScaleQuantizationType::FP16_TO_MXFP8)
{
reinterpret_cast<uint64_t*>(out)[outOffset]
= cvt_warp_fp16_to_mxfp8<Type, SF_VEC_SIZE>(in_vec, sf_out);
}
}
}
}
}
asm volatile("griddepcontrol.launch_dependents;");
#endif
}
__global__ void block_scale_interleave_kernel(
int numbatches, int numRows, int numCols, uint8_t const* SFIn, uint8_t* SFOutput);
} // namespace kernels
} // namespace tensorrt_llm