Gumiho: A Hybrid Architecture to Prioritize Early Tokens in Speculative Decoding

Fuente: arXiv
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Autores principales: Li, Jinze, Xu, Yixing, Huang, Haiduo, Yin, Xuanwu, Li, Dong, Ngai, Edith C. H., Barsoum, Emad
Formato: Preprint
Publicado: 2025
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author Li, Jinze
Xu, Yixing
Huang, Haiduo
Yin, Xuanwu
Li, Dong
Ngai, Edith C. H.
Barsoum, Emad
author_facet Li, Jinze
Xu, Yixing
Huang, Haiduo
Yin, Xuanwu
Li, Dong
Ngai, Edith C. H.
Barsoum, Emad
contents Speculative decoding (SPD) aims to accelerate the auto-regressive token generation process of a target Large Language Model (LLM). Some approaches employ a draft model with multiple heads to predict a sequence of future tokens, where each head handles a token in the sequence. The target LLM verifies the predicted sequence and accepts aligned tokens, enabling efficient multi-token generation. However, existing methods assume that all tokens within a sequence are equally important, employing identical head structures and relying on a single-generation paradigm, either serial or parallel. To this end, we theoretically demonstrate that initial tokens in the draft sequence are more important than later ones. Building on this insight, we propose Gumiho, a hybrid model combining serial and parallel heads. Specifically, given the critical importance of early tokens, we employ a sophisticated Transformer architecture for the early draft heads in a serial configuration to improve accuracy. For later tokens, we utilize multiple lightweight MLP heads operating in parallel to enhance efficiency. By allocating more advanced model structures and longer running times to the early heads, Gumiho achieves improved overall performance. The experimental results demonstrate that our method outperforms existing approaches, fully validating its effectiveness.
format Preprint
id arxiv_https___arxiv_org_abs_2503_10135
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Gumiho: A Hybrid Architecture to Prioritize Early Tokens in Speculative Decoding
Li, Jinze
Xu, Yixing
Huang, Haiduo
Yin, Xuanwu
Li, Dong
Ngai, Edith C. H.
Barsoum, Emad
Computation and Language
Artificial Intelligence
Machine Learning
Speculative decoding (SPD) aims to accelerate the auto-regressive token generation process of a target Large Language Model (LLM). Some approaches employ a draft model with multiple heads to predict a sequence of future tokens, where each head handles a token in the sequence. The target LLM verifies the predicted sequence and accepts aligned tokens, enabling efficient multi-token generation. However, existing methods assume that all tokens within a sequence are equally important, employing identical head structures and relying on a single-generation paradigm, either serial or parallel. To this end, we theoretically demonstrate that initial tokens in the draft sequence are more important than later ones. Building on this insight, we propose Gumiho, a hybrid model combining serial and parallel heads. Specifically, given the critical importance of early tokens, we employ a sophisticated Transformer architecture for the early draft heads in a serial configuration to improve accuracy. For later tokens, we utilize multiple lightweight MLP heads operating in parallel to enhance efficiency. By allocating more advanced model structures and longer running times to the early heads, Gumiho achieves improved overall performance. The experimental results demonstrate that our method outperforms existing approaches, fully validating its effectiveness.
title Gumiho: A Hybrid Architecture to Prioritize Early Tokens in Speculative Decoding
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2503.10135