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silu_and_mul nvfp4 quanization fusion rework #1927

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Oct 23, 2025
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silu_and_mul nvfp4 quanization fusion rework #1927

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Revert "[Quantization] Add per-expert global scaling factor for fp4 b…
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107 changes: 54 additions & 53 deletions csrc/nv_internal/cpp/kernels/quantization.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -102,7 +102,7 @@ void invokeMxFP8Quantization(int b, int m, int n, int padded_n, T const* input,
&config,
quantize_with_block_size<BlockScaleQuantizationType::FP16_TO_MXFP8, T, SF_VEC_SIZE, true>, b,
m, n, padded_n, input, nullptr, reinterpret_cast<uint32_t*>(output),
reinterpret_cast<uint32_t*>(SFOuput), layout, /*mask=*/nullptr);
reinterpret_cast<uint32_t*>(SFOuput), layout);
}

// Do per-token (row) quantization from fp16/bf16/fp32 to int8/fp8_e4m3.
Expand Down Expand Up @@ -164,11 +164,12 @@ INSTANTIATE_INVOKE_PER_TOKEN_QUANTIZATION(__nv_bfloat16, __nv_fp8_e4m3);

////////////////////////////////////////////////////////////////////////////////////////////////////
// FP4/MXFP8 Quantization

template <typename T, int SF_VEC_SIZE>
void invokeFP4Quantization(int b, int m, int n, T const* input, float const* SFScale,
int64_t* output, int32_t* SFOuput, bool useUE8M0,
QuantizationSFLayout layout, int multiProcessorCount,
int32_t const* mask, bool enable_pdl, cudaStream_t stream) {
QuantizationSFLayout layout, int multiProcessorCount, bool enable_pdl,
cudaStream_t stream) {
#ifdef ENABLE_FP8
if constexpr (std::is_same_v<T, __nv_fp8_e4m3>) {
// Grid, Block size.
Expand All @@ -186,7 +187,7 @@ void invokeFP4Quantization(int b, int m, int n, T const* input, float const* SFS
T, SF_VEC_SIZE, false>;
kernel_instance<<<grid, block, 0, stream>>>(b, m, n, n, input, SFScale,
reinterpret_cast<uint32_t*>(output),
reinterpret_cast<uint32_t*>(SFOuput), layout, mask);
reinterpret_cast<uint32_t*>(SFOuput), layout);

} else
#endif
Expand Down Expand Up @@ -217,42 +218,10 @@ void invokeFP4Quantization(int b, int m, int n, T const* input, float const* SFS
config.attrs = attrs;
cudaLaunchKernelEx(&config, kernel_instance, b, m, n, n, input, SFScale,
reinterpret_cast<uint32_t*>(output), reinterpret_cast<uint32_t*>(SFOuput),
layout, mask);
layout);
}
}

template <typename T, int SF_VEC_SIZE>
void invokeSiluAndMulFP4Quantization(int b, int m, int n, T const* input, float const* SFScale,
int32_t const* mask, int64_t* output, int32_t* SFOuput,
QuantizationSFLayout layout, int multiProcessorCount,
bool enable_pdl, cudaStream_t stream) {
// Grid, Block size.
// Each thread converts 8 values.
dim3 block(std::min(int(n / CVT_ELTS_PER_THREAD), 512));
// Get number of blocks per SM (assume we can fully utilize the SM).
int const numBlocksPerSM = std::max(1u, 2048u / block.x);
dim3 grid(std::min(int(m), multiProcessorCount * numBlocksPerSM));

// Launch the cvt kernel.
auto* kernel_instance =
&silu_mul_quantize_with_block_size<BlockScaleQuantizationType::FP16_TO_FP4, T, SF_VEC_SIZE,
false>;

cudaLaunchConfig_t config;
config.gridDim = grid;
config.blockDim = block;
config.dynamicSmemBytes = 0;
config.stream = stream;
cudaLaunchAttribute attrs[1];
attrs[0].id = cudaLaunchAttributeProgrammaticStreamSerialization;
attrs[0].val.programmaticStreamSerializationAllowed = enable_pdl;
config.numAttrs = 1;
config.attrs = attrs;
cudaLaunchKernelEx(&config, kernel_instance, b, m, n / 2, n / 2, input, SFScale,
reinterpret_cast<uint32_t*>(output), reinterpret_cast<uint32_t*>(SFOuput),
layout, mask);
}

__global__ void block_scale_interleave_kernel(int numBatches, int numRows, int numRowsPadded,
int numCols, int numColsPadded, uint8_t const* SFIn,
uint8_t* SFOutput) {
Expand Down Expand Up @@ -325,57 +294,89 @@ void invokeBlockScaleInterleaveReverse(int b, int m, int n, uint8_t const* SFIn,
block_scale_interleave_reverse_kernel<<<grid, block, 0, stream>>>(b, m, n, SFIn, SFOutput);
}

template <typename T>
void invokeSiluAndMulNVFP4Quantization(void* output, void* output_scale, void* input,
void* input_global_scale, void* mask, bool use_silu_and_mul,
int m_topk, int k, int n_experts, cudaStream_t stream) {
int device;
cudaGetDevice(&device);
int multiProcessorCount;
cudaDeviceGetAttribute(&multiProcessorCount, cudaDevAttrMultiProcessorCount, device);

// Grid, Block size.
// Each thread converts 8 values.
int const workSizePerRow = k / CVT_ELTS_PER_THREAD;
int const totalWorkSize = m_topk * workSizePerRow;
dim3 block(std::min(workSizePerRow, 512));
// Get number of blocks per SM (assume we can fully utilize the SM).
int const numBlocksPerSM = 2048 / block.x;
dim3 grid(std::min(static_cast<int>((totalWorkSize + block.x - 1) / block.x),
multiProcessorCount * numBlocksPerSM));
while (grid.x <= multiProcessorCount && block.x > 64) {
grid.x *= 2;
block.x = (block.x + 1) / 2;
}

// TODO(kaixih@nvidia): Should relax this to allow any grid size.
// [email protected]: only deal with mask case
assert(mask != nullptr);
grid.x = (grid.x + n_experts - 1) / n_experts * n_experts;
cvt_fp16_to_fp4_expert<T, false><<<grid, block, 0, stream>>>(
m_topk, k, reinterpret_cast<T*>(input), reinterpret_cast<float*>(input_global_scale),
reinterpret_cast<uint32_t*>(output), reinterpret_cast<uint32_t*>(output_scale),
reinterpret_cast<int32_t*>(mask), use_silu_and_mul, n_experts);
return;
}

// Instantiate the function.
template void invokeFP4Quantization<half, 16>(int b, int m, int n, half const* input,
float const* SFScale, int64_t* output,
int32_t* SFOuput, bool useUE8M0,
QuantizationSFLayout layout, int multiProcessorCount,
int32_t const* mask, bool enable_pdl,
cudaStream_t stream);
bool enable_pdl, cudaStream_t stream);
template void invokeFP4Quantization<half, 32>(int b, int m, int n, half const* input,
float const* SFScale, int64_t* output,
int32_t* SFOuput, bool useUE8M0,
QuantizationSFLayout layout, int multiProcessorCount,
int32_t const* mask, bool enable_pdl,
cudaStream_t stream);
bool enable_pdl, cudaStream_t stream);
template void invokeMxFP8Quantization<half>(int b, int m, int n, int padded_n, half const* input,
int64_t* output, int32_t* SFOuput,
QuantizationSFLayout layout, int multiProcessorCount,
bool enable_pdl, cudaStream_t stream);
template void invokeSiluAndMulFP4Quantization<half, 16>(
int b, int m, int n, half const* input, float const* globalScale, int32_t const* mask,
int64_t* output, int32_t* SFOuput, QuantizationSFLayout layout, int multiProcessorCount,
bool enable_pdl, cudaStream_t stream);
template void invokeSiluAndMulNVFP4Quantization<half>(void* output, void* output_scale, void* input,
void* input_global_scale, void* mask,
bool use_silu_and_mul, int m_topk, int k,
int n_experts, cudaStream_t stream);

#ifdef ENABLE_BF16
template void invokeFP4Quantization<__nv_bfloat16, 16>(
int b, int m, int n, __nv_bfloat16 const* input, float const* SFScale, int64_t* output,
int32_t* SFOuput, bool useUE8M0, QuantizationSFLayout layout, int multiProcessorCount,
int32_t const* mask, bool enable_pdl, cudaStream_t stream);
bool enable_pdl, cudaStream_t stream);
template void invokeFP4Quantization<__nv_bfloat16, 32>(
int b, int m, int n, __nv_bfloat16 const* input, float const* SFScale, int64_t* output,
int32_t* SFOuput, bool useUE8M0, QuantizationSFLayout layout, int multiProcessorCount,
int32_t const* mask, bool enable_pdl, cudaStream_t stream);
bool enable_pdl, cudaStream_t stream);
template void invokeMxFP8Quantization<__nv_bfloat16>(int b, int m, int n, int padded_n,
__nv_bfloat16 const* input, int64_t* output,
int32_t* SFOuput, QuantizationSFLayout layout,
int multiProcessorCount, bool enable_pdl,
cudaStream_t stream);
template void invokeSiluAndMulFP4Quantization<__nv_bfloat16, 16>(
int b, int m, int n, __nv_bfloat16 const* input, float const* globalScale, int32_t const* mask,
int64_t* output, int32_t* SFOuput, QuantizationSFLayout layout, int multiProcessorCount,
bool enable_pdl, cudaStream_t stream);
template void invokeSiluAndMulNVFP4Quantization<__nv_bfloat16>(
void* output, void* output_scale, void* input, void* input_global_scale, void* mask,
bool use_silu_and_mul, int m_topk, int k, int n_experts, cudaStream_t stream);

#endif

#ifdef ENABLE_FP8
template void invokeFP4Quantization<__nv_fp8_e4m3, 16>(
int b, int m, int n, __nv_fp8_e4m3 const* input, float const* SFScale, int64_t* output,
int32_t* SFOuput, bool useUE8M0, QuantizationSFLayout layout, int multiProcessorCount,
int32_t const* mask, bool enable_pdl, cudaStream_t stream);
bool enable_pdl, cudaStream_t stream);
template void invokeFP4Quantization<__nv_fp8_e4m3, 32>(
int b, int m, int n, __nv_fp8_e4m3 const* input, float const* SFScale, int64_t* output,
int32_t* SFOuput, bool useUE8M0, QuantizationSFLayout layout, int multiProcessorCount,
int32_t const* mask, bool enable_pdl, cudaStream_t stream);
bool enable_pdl, cudaStream_t stream);

#endif

Expand Down
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