MoESD: Unveil Speculative Decoding's Potential for Accelerating Sparse MoE

Fuente: arXiv
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Autori principali: Huang, Zongle, Zhu, Lei, Zhan, Zongyuan, Hu, Ting, Mao, Weikai, Yu, Xianzhi, Liu, Yongpan, Zhang, Tianyu
Natura: Preprint
Pubblicazione: 2025
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author Huang, Zongle
Zhu, Lei
Zhan, Zongyuan
Hu, Ting
Mao, Weikai
Yu, Xianzhi
Liu, Yongpan
Zhang, Tianyu
author_facet Huang, Zongle
Zhu, Lei
Zhan, Zongyuan
Hu, Ting
Mao, Weikai
Yu, Xianzhi
Liu, Yongpan
Zhang, Tianyu
contents Large Language Models (LLMs) have achieved remarkable success across many applications, with Mixture of Experts (MoE) models demonstrating great potential. Compared to traditional dense models, MoEs achieve better performance with less computation. Speculative decoding (SD) is a widely used technique to accelerate LLM inference without accuracy loss, but it has been considered efficient only for dense models. In this work, we first demonstrate that, under medium batch sizes, MoE surprisingly benefits more from SD than dense models. Furthermore, as MoE becomes sparser -- the prevailing trend in MoE designs -- the batch size range where SD acceleration is expected to be effective becomes broader. To quantitatively understand tradeoffs involved in SD, we develop a reliable modeling based on theoretical analyses. While current SD research primarily focuses on improving acceptance rates of algorithms, changes in workload and model architecture can still lead to degraded SD acceleration even with high acceptance rates. To address this limitation, we introduce a new metric 'target efficiency' that characterizes these effects, thus helping researchers identify system bottlenecks and understand SD acceleration more comprehensively. For scenarios like private serving, this work unveils a new perspective to speed up MoE inference, where existing solutions struggle. Experiments on different GPUs show up to 2.29x speedup for Qwen2-57B-A14B at medium batch sizes and validate our theoretical predictions.
format Preprint
id arxiv_https___arxiv_org_abs_2505_19645
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MoESD: Unveil Speculative Decoding's Potential for Accelerating Sparse MoE
Huang, Zongle
Zhu, Lei
Zhan, Zongyuan
Hu, Ting
Mao, Weikai
Yu, Xianzhi
Liu, Yongpan
Zhang, Tianyu
Machine Learning
Artificial Intelligence
Large Language Models (LLMs) have achieved remarkable success across many applications, with Mixture of Experts (MoE) models demonstrating great potential. Compared to traditional dense models, MoEs achieve better performance with less computation. Speculative decoding (SD) is a widely used technique to accelerate LLM inference without accuracy loss, but it has been considered efficient only for dense models. In this work, we first demonstrate that, under medium batch sizes, MoE surprisingly benefits more from SD than dense models. Furthermore, as MoE becomes sparser -- the prevailing trend in MoE designs -- the batch size range where SD acceleration is expected to be effective becomes broader. To quantitatively understand tradeoffs involved in SD, we develop a reliable modeling based on theoretical analyses. While current SD research primarily focuses on improving acceptance rates of algorithms, changes in workload and model architecture can still lead to degraded SD acceleration even with high acceptance rates. To address this limitation, we introduce a new metric 'target efficiency' that characterizes these effects, thus helping researchers identify system bottlenecks and understand SD acceleration more comprehensively. For scenarios like private serving, this work unveils a new perspective to speed up MoE inference, where existing solutions struggle. Experiments on different GPUs show up to 2.29x speedup for Qwen2-57B-A14B at medium batch sizes and validate our theoretical predictions.
title MoESD: Unveil Speculative Decoding's Potential for Accelerating Sparse MoE
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2505.19645