EDSD: Entropy-Driven Design for Faster Speculative Decoding

Longkai Cheng, Ximing Wang, Jiangcai Zhu, Kailai Shao, Chao Chen, Haixiang Hu


Abstract
Speculative decoding has emerged as a promising paradigm for accelerating large language model inference by leveraging a lightweight draft model to generate multiple candidate tokens. However, existing methods often incur substantial training overhead to mitigate information misalignment between autoregressive draft model training and decoding. To address this challenge, we propose EDSD, an Entropy-Driven Speculative Decoding framework that uses entropy as a unified, interpretable signal for both draft model training and architectural design. EDSD drives the draft model to progressively align with the target model in an easy-to-hard manner while establishing token-level alignment as a dominant design principle. Extensive experiments on seven LLMs demonstrate that EDSD improves training efficiency by 24.8%, increases the average acceptance length by 4.0%, and achieves a 4.1% speedup compared to state-of-the-art methods. Furthermore, EDSD improves robustness to system prompt variations by more than 5x. Our findings establish entropy-driven alignment as an effective and principled foundation for efficient speculative decoding.
Anthology ID:
2026.acl-long.2145
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
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Publisher:
Association for Computational Linguistics
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Pages:
46243–46260
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URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.2145/
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Cite (ACL):
Longkai Cheng, Ximing Wang, Jiangcai Zhu, Kailai Shao, Chao Chen, and Haixiang Hu. 2026. EDSD: Entropy-Driven Design for Faster Speculative Decoding. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 46243–46260, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
EDSD: Entropy-Driven Design for Faster Speculative Decoding (Cheng et al., ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-long.2145.pdf
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