Polybasic Speculative Decoding Through a Theoretical Perspective

Fuente: arXiv
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Autori principali: Wang, Ruilin, Li, Huixia, Ma, Yuexiao, Zheng, Xiawu, Chao, Fei, Xiao, Xuefeng, Ji, Rongrong
Natura: Preprint
Pubblicazione: 2025
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author Wang, Ruilin
Li, Huixia
Ma, Yuexiao
Zheng, Xiawu
Chao, Fei
Xiao, Xuefeng
Ji, Rongrong
author_facet Wang, Ruilin
Li, Huixia
Ma, Yuexiao
Zheng, Xiawu
Chao, Fei
Xiao, Xuefeng
Ji, Rongrong
contents Inference latency stands as a critical bottleneck in the large-scale deployment of Large Language Models (LLMs). Speculative decoding methods have recently shown promise in accelerating inference without compromising the output distribution. However, existing work typically relies on a dualistic draft-verify framework and lacks rigorous theoretical grounding. In this paper, we introduce a novel \emph{polybasic} speculative decoding framework, underpinned by a comprehensive theoretical analysis. Specifically, we prove a fundamental theorem that characterizes the optimal inference time for multi-model speculative decoding systems, shedding light on how to extend beyond the dualistic approach to a more general polybasic paradigm. Through our theoretical investigation of multi-model token generation, we expose and optimize the interplay between model capabilities, acceptance lengths, and overall computational cost. Our framework supports both standalone implementation and integration with existing speculative techniques, leading to accelerated performance in practice. Experimental results across multiple model families demonstrate that our approach yields speedup ratios ranging from $3.31\times$ to $4.01\times$ for LLaMA2-Chat 7B, up to $3.87 \times$ for LLaMA3-8B, up to $4.43 \times$ for Vicuna-7B and up to $3.85 \times$ for Qwen2-7B -- all while preserving the original output distribution. We release our theoretical proofs and implementation code to facilitate further investigation into polybasic speculative decoding.
format Preprint
id arxiv_https___arxiv_org_abs_2510_26527
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Polybasic Speculative Decoding Through a Theoretical Perspective
Wang, Ruilin
Li, Huixia
Ma, Yuexiao
Zheng, Xiawu
Chao, Fei
Xiao, Xuefeng
Ji, Rongrong
Machine Learning
Inference latency stands as a critical bottleneck in the large-scale deployment of Large Language Models (LLMs). Speculative decoding methods have recently shown promise in accelerating inference without compromising the output distribution. However, existing work typically relies on a dualistic draft-verify framework and lacks rigorous theoretical grounding. In this paper, we introduce a novel \emph{polybasic} speculative decoding framework, underpinned by a comprehensive theoretical analysis. Specifically, we prove a fundamental theorem that characterizes the optimal inference time for multi-model speculative decoding systems, shedding light on how to extend beyond the dualistic approach to a more general polybasic paradigm. Through our theoretical investigation of multi-model token generation, we expose and optimize the interplay between model capabilities, acceptance lengths, and overall computational cost. Our framework supports both standalone implementation and integration with existing speculative techniques, leading to accelerated performance in practice. Experimental results across multiple model families demonstrate that our approach yields speedup ratios ranging from $3.31\times$ to $4.01\times$ for LLaMA2-Chat 7B, up to $3.87 \times$ for LLaMA3-8B, up to $4.43 \times$ for Vicuna-7B and up to $3.85 \times$ for Qwen2-7B -- all while preserving the original output distribution. We release our theoretical proofs and implementation code to facilitate further investigation into polybasic speculative decoding.
title Polybasic Speculative Decoding Through a Theoretical Perspective
topic Machine Learning
url https://arxiv.org/abs/2510.26527