- split quantize into quantize.cuh, templated on input type (bf16/fp16/fp32) - rename pybind entry quantize_bf16 to quantize; validate the fmt enum - fix fp8x2 packing: one 32-bit word packs two pairs (halves were dropped) - drop the dead OutFp8 template param; GEMM output is always bf16 - fp8_state.reset() restores recipe/format defaults too (test state leak) - rewrite tests for the two-primitive API with fp32-domain amax references
114 lines
4.5 KiB
C++
114 lines
4.5 KiB
C++
#pragma once
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#include <cuda_bf16.h>
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#include <cuda_fp8.h>
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#include <cuda_runtime.h>
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#include <cstdint>
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// Pure POD/traits header — no .cuh/CUDA-kernel includes; raw __nv_* type
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// spellings only.
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namespace astrai {
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namespace fp8 {
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// Compile-time FP8 format: E4M3 (forward / high precision, max 448) or
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// E5M2 (gradient / large dynamic range, max 57344).
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enum class FP8Format : int {
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E4M3 = 0,
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E5M2 = 1,
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};
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// Operand memory layouts as types (CUTLASS-style tags). The tag names the
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// storage order of the raw buffer relative to the operand's canonical GEMM
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// matrix — A is [M][K], B is [K][N]:
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// A RowMajor = [M][K] storage (K-contiguous rows; the default)
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// A ColMajor = [K][M] storage (M-contiguous; A^T)
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// B RowMajor = [K][N] storage (N-contiguous; the plain a @ b operand)
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// B ColMajor = [N][K] storage (K-contiguous; the nn.Linear weight layout)
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// Empty tags: selection happens by type at compile time (see load_operand_tile).
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struct RowMajor {};
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struct ColMajor {};
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// Transpose of a layout tag: the same buffer with the rows and contract dims
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// swapped. B's tag is relative to the canonical [K][N] GEMM matrix, so the
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// stage-load (which views any operand as [rows][contract]) sees the transposed
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// tag — this trait makes that inversion explicit.
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template <typename Layout>
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struct transpose_layout;
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template <>
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struct transpose_layout<RowMajor> {
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using type = ColMajor;
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};
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template <>
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struct transpose_layout<ColMajor> {
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using type = RowMajor;
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};
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template <typename Layout>
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using transpose_layout_t = typename transpose_layout<Layout>::type;
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// Compile-time tile configuration, mirroring KernelTraits<HEAD_DIM, BC,
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// WARPS, STAGES> in the attention kernels. `Fmt` selects the FP8 conversion
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// and the MMA PTX mnemonic; the remaining parameters shape the CTA tile and
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// the cp.async pipeline depth.
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template <FP8Format Fmt, int BlockM, int BlockN, int K, int Stages>
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struct Fp8GemmTraits {
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static constexpr FP8Format kFormat = Fmt;
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static constexpr int kBlockM = BlockM;
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static constexpr int kBlockN = BlockN;
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static constexpr int kK = K;
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static constexpr int kStages = Stages;
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static constexpr bool kIsE5M2 = (Fmt == FP8Format::E5M2);
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static constexpr __nv_fp8_interpretation_t kNvFormat =
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kIsE5M2 ? __NV_E5M2 : __NV_E4M3;
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static constexpr float kFp8Max = kIsE5M2 ? 57344.0f : 448.0f;
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// Derived launch geometry: 64x32 warp tiles give the CTA thread count.
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// The shared-memory budget is layout-aware (crosswise operands add K-
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// major staging + a canonical buffer), so it lives in Fp8GemmSmem in
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// gemm.cuh together with the resident-CTA hint for __launch_bounds__.
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static constexpr int kCtaThreads = (BlockM / 64) * (BlockN / 32) * 32;
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};
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// Quantize-kernel parameter POD: float input (bf16 / fp16 / fp32) -> FP8
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// with fused amax.
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struct FP8QuantizeParams {
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// Float input and FP8 output buffers; scale is the quantization
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// multiplier (device scalar). amax (may be null) is zero-initialized by
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// the binding and receives the raw-domain absolute maximum.
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const void* __restrict__ input_ptr = nullptr;
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void* __restrict__ output_ptr = nullptr;
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const float* __restrict__ scale = nullptr;
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float* __restrict__ amax = nullptr;
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// Element count (only the elementwise quantize kernel uses it).
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int total = 0;
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};
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// Unified GEMM parameter POD, mirroring AttentionParams: one struct flows
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// through the pre-quantized GEMM kernels. Each kernel touches only the
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// fields it needs; buffers are raw pointers packed by the torch binding.
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// Pointer members default to null so optional paths cannot hold garbage.
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struct FP8Params {
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// Inputs: a/b are FP8 for the pre-quantized path. Scales are
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// quantization steps (device scalars).
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const void* __restrict__ a_ptr = nullptr;
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const void* __restrict__ b_ptr = nullptr;
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void* __restrict__ out_ptr = nullptr;
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const float* __restrict__ scale = nullptr;
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// Shapes. `int` covers every realistic LLM shape; the kernels promote
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// to int64 for all pointer arithmetic.
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int m, n, k;
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// Physical leading dimensions (column count, i.e. row stride) of A and
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// B. For a non-transposed operand the stride equals the contract dim;
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// for a transposed operand it is the operand's own column count. The
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// binding packs these so the kernel reads both buffers either naturally
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// or transposed depending on the LayoutA/LayoutB tags (see gemm.cuh).
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int a_ld, b_ld;
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};
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} // namespace fp8
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} // namespace astrai
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