SPIN: Accelerating Large Language Model Inference with Heterogeneous Speculative Models

Fuente: arXiv
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Main Authors: Chen, Fahao, Li, Peng, Luan, Tom H., Su, Zhou, Deng, Jing
Format: Preprint
Published: 2025
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author Chen, Fahao
Li, Peng
Luan, Tom H.
Su, Zhou
Deng, Jing
author_facet Chen, Fahao
Li, Peng
Luan, Tom H.
Su, Zhou
Deng, Jing
contents Speculative decoding has been shown as an effective way to accelerate Large Language Model (LLM) inference by using a Small Speculative Model (SSM) to generate candidate tokens in a so-called speculation phase, which are subsequently verified by the LLM in a verification phase. However, current state-of-the-art speculative decoding approaches have three key limitations: handling requests with varying difficulty using homogeneous SSMs, lack of robust support for batch processing, and insufficient holistic optimization for both speculation and verification phases. In this paper, we introduce SPIN, an efficient LLM inference serving system based on speculative decoding, designed to address these challenges through three main innovations. First, SPIN improves token speculation by using multiple heterogeneous SSMs, with a learning-based algorithm for SSM selection that operates without prior knowledge of request difficulty. Second, SPIN employs a request decomposition method to minimize batching overhead during LLM verification. Finally, SPIN orchestrates speculation and verification phases by pipelining their executions on GPUs to achieve further acceleration. Experimental results demonstrate that SPIN significantly outperforms state-of-the-art methods, achieving a performance increase of approximately 2.28X.
format Preprint
id arxiv_https___arxiv_org_abs_2503_15921
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SPIN: Accelerating Large Language Model Inference with Heterogeneous Speculative Models
Chen, Fahao
Li, Peng
Luan, Tom H.
Su, Zhou
Deng, Jing
Distributed, Parallel, and Cluster Computing
Speculative decoding has been shown as an effective way to accelerate Large Language Model (LLM) inference by using a Small Speculative Model (SSM) to generate candidate tokens in a so-called speculation phase, which are subsequently verified by the LLM in a verification phase. However, current state-of-the-art speculative decoding approaches have three key limitations: handling requests with varying difficulty using homogeneous SSMs, lack of robust support for batch processing, and insufficient holistic optimization for both speculation and verification phases. In this paper, we introduce SPIN, an efficient LLM inference serving system based on speculative decoding, designed to address these challenges through three main innovations. First, SPIN improves token speculation by using multiple heterogeneous SSMs, with a learning-based algorithm for SSM selection that operates without prior knowledge of request difficulty. Second, SPIN employs a request decomposition method to minimize batching overhead during LLM verification. Finally, SPIN orchestrates speculation and verification phases by pipelining their executions on GPUs to achieve further acceleration. Experimental results demonstrate that SPIN significantly outperforms state-of-the-art methods, achieving a performance increase of approximately 2.28X.
title SPIN: Accelerating Large Language Model Inference with Heterogeneous Speculative Models
topic Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2503.15921