arXiv:2510.26527cs.LG2025-10ICML被引 1

提出多模型推测解码新框架,显著降低大模型推理延迟。

Polybasic Speculative Decoding Through a Theoretical Perspective

  • 设计多基础推测解码机制,突破传统双模型范式
  • 实测速度提升3.31倍至4.43倍,输出分布不变
  • 理论完备,适合追求推理加速的工业与研究场景

推理延迟是大规模部署大语言模型的关键瓶颈。推测解码方法近期展现出在不改变输出分布的前提下加速推理的潜力。然而,现有工作通常依赖于双阶段草稿-验证框架,且缺乏严格的理论基础。本文提出一种全新的多基础(polybasic)推测解码框架,并基于全面的理论分析展开研究。我们证明了一个基本定理,刻画了多模型推测解码系统的最优推理时间,揭示了如何从双模型范式扩展到更通用的多基础范式。通过对多模型标记生成的理论探究,我们揭示并优化了模型能力、接受长度与整体计算成本之间的相互作用。该框架既支持独立实现,也可与现有推测技术集成,在实践中实现加速。跨多个模型家族的实验结果表明,本方法在LLaMA2-Chat 7B上实现3.31×至4.01×的加速,对LLaMA3-8B达3.87×,Vicuna-7B达4.43×,Qwen2-7B达3.85×,同时保持原始输出分布。我们开源了理论证明与实现代码,以促进对多基础推测解码的进一步研究。

原文摘要 · Abstract (English)

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.

推理加速推测解码大模型

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