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Main Authors: Huang, Haiduo, Song, Jiangcheng, Zhao, Wenzhe, Ren, Pengju
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.20416
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author Huang, Haiduo
Song, Jiangcheng
Zhao, Wenzhe
Ren, Pengju
author_facet Huang, Haiduo
Song, Jiangcheng
Zhao, Wenzhe
Ren, Pengju
contents 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.
format Preprint
id arxiv_https___arxiv_org_abs_2509_20416
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FastEagle: Cascaded Drafting for Accelerating Speculative Decoding
Huang, Haiduo
Song, Jiangcheng
Zhao, Wenzhe
Ren, Pengju
Machine Learning
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.
title FastEagle: Cascaded Drafting for Accelerating Speculative Decoding
topic Machine Learning
url https://arxiv.org/abs/2509.20416