arXiv:2509.20416cs.LG2025-09被引 2

用单次前向传播完成多步草案生成,显著提速大模型推理

FastEagle: Cascaded Drafting for Accelerating Speculative Decoding

  • 采用轻量级层叠结构替代传统逐词生成,实现一次前向传播出完整草案
  • 在多个模型和任务上速度提升超EAGLE-3,平均采纳长度相当
  • 适合追求高吞吐、低延迟的部署场景,尤其适合实时生成应用

推测解码通过并行生成候选文本并验证来加速生成,但当前最优草案生成器(如EAGLE)仍需N次串行计算生成N个词。我们提出FastEagle,一种非自回归的级联草案生成器,可在单次前向传播中输出完整草案。FastEagle以轻量级层叠结构替代时间步,通过分层监督训练缓解误差累积。结合约束草案树结构,保持无损验证开销。在多个LLM(Vicuna-13B、LLaMA-Instruct 3.x、DeepSeek-R1-Distill-LLaMA)和任务(MT-Bench、HumanEval、GSM8K、CNN/DM、Alpaca)上,FastEagle在贪婪与随机解码下均持续优于EAGLE-3的速度表现,且平均采纳长度相当。结果表明,消除草案生成中的串行依赖是实现无损大模型推理加速的可行路径。

原文摘要 · Abstract (English)

Speculative decoding accelerates generation by drafting candidates and verifying them in parallel, yet state-of-the-art drafters (e.g., EAGLE) still require N sequential passes to propose N tokens. We present FastEagle, a non-autoregressive cascaded drafter that emits an entire draft in a single forward pass. FastEagle replaces temporal steps with a lightweight layer cascade and trains with layer-wise supervision to mitigate error accumulation. Coupled with a constrained draft tree that preserves lossless verification cost, FastEagle delivers substantial wall-clock speedups over strong autoregressive drafters while maintaining competitive acceptance behavior. Across multiple LLMs (Vicuna-13B, LLaMA-Instruct 3.x, and DeepSeek-R1-Distill-LLaMA) and tasks (MT-Bench, HumanEval, GSM8K, CNN/DM, Alpaca), FastEagle consistently outperforms EAGLE-3 in speedup under both greedy and stochastic decoding, with comparable average acceptance lengths. These results indicate that removing sequential dependencies in drafting is a practical path toward lossless LLM inference acceleration.

大模型推理推测解码加速生成非自回归

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