52 lines
1.7 KiB
Python
52 lines
1.7 KiB
Python
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"""Python wrapper for the append_swa CUDA kernel.
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Writes raw BF16 KV into the FP8/BF16 split state cache layout.
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Quantizes the non-RoPE half BF16 -> FP8 (E4M3 amax-based scaling),
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writes the RoPE half as-is, computes per-token inverse scale, and
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updates the ring buffer head + position field.
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One block per token. Threads cooperatively:
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1. Compute amax over fp8-dim elements (warp reduce).
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2. Quantize BF16 -> FP8 with per-token scale.
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3. Write FP8 entries + BF16 RoPE entries + inv_scale + position.
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4. Atomic increment ring buffer head.
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"""
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import os
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import torch
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from torch.utils.cpp_extension import load
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_kernel_module = None
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def _get_kernel_module():
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global _kernel_module
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if _kernel_module is not None:
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return _kernel_module
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kernel_dir = os.path.join(os.path.dirname(__file__), "..", "cuda")
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_kernel_module = load(
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name="append_swa",
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sources=[os.path.join(kernel_dir, "append_swa.cu")],
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extra_cuda_cflags=["-O3", "--generate-code=arch=compute_100a,code=[sm_100a]"],
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verbose=False,
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)
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return _kernel_module
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def append_swa_kernel(
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raw_kv: torch.Tensor, # (T, head_dim) BF16
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request_slots: torch.Tensor, # (T,) int32
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positions: torch.Tensor, # (T,) int32
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swa_fp8: torch.Tensor, # (max_req, n_win, fp8_dim) uint8
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swa_rope: torch.Tensor, # (max_req, n_win, rope_dim) BF16
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swa_inv: torch.Tensor, # (max_req, n_win) FP32
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swa_pos: torch.Tensor, # (max_req, n_win) int32
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swa_head: torch.Tensor, # (max_req,) int32
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rope_dim: int,
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):
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mod = _get_kernel_module()
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mod.append_swa(
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raw_kv, request_slots, positions,
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swa_fp8, swa_rope, swa_inv, swa_pos, swa_head,
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rope_dim,
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)
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