ViperEkura
8c052c99ee
- add FlashAttnBackend (ATTN_BACKEND.FLASH) using flash_attn_func with KV-cache gather + GQA, mirroring TorchNativeBackend - add flash_attn_available() probe gated on compute capability plus a real-kernel smoke test, cached at first use - lazy-import flash-attn via importlib so it stays an optional dependency, raising clear errors when unusable - add 'flash' optional extra (flash-attn>=2.6) and export the new backend
54 lines
1.5 KiB
Python
54 lines
1.5 KiB
Python
"""CUDA attention kernel wrappers with torch fallback.
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Public API:
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- ``attn_decode`` — single-query decode attention
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- ``attn_prefill`` — multi-query prefill attention
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- ``attn_paged_decode`` — paged decode attention (direct page-table access)
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- ``AttentionBackend`` — ABC for attention computation strategies
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- ``TorchNativeBackend`` — default SDPA backend with KV cache I/O
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- ``CudaBackend`` — CUDA kernel backend with paged decode + prefill
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Layout convention: all q/k/v are ``[batch, seq_len, n_heads, head_dim]``
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(blhd). Scale is always ``1/sqrt(head_dim)``.
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Each wrapper calls its compiled CUDA kernel directly. Fallback to torch
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SDPA is handled by the attention backend, not the wrapper functions.
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"""
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from astrai.extension.attention_backend import (
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ATTN_BACKEND,
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AttentionBackend,
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CudaBackend,
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FlashAttnBackend,
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TorchNativeBackend,
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attention,
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attn_backend,
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get_backend,
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)
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from astrai.extension.attention_ops import (
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TensorLayout,
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attn_decode,
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attn_paged_decode,
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attn_prefill,
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)
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from astrai.extension.loader import KERNEL_NAMES, is_available
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from astrai.extension.rotary_backend import apply_rotary_emb
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__all__ = [
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"ATTN_BACKEND",
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"AttentionBackend",
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"CudaBackend",
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"TorchNativeBackend",
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"FlashAttnBackend",
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"TensorLayout",
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"attention",
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"attn_backend",
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"get_backend",
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"attn_decode",
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"attn_paged_decode",
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"attn_prefill",
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"is_available",
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"KERNEL_NAMES",
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"apply_rotary_emb",
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]
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