GuiLoMo: Allocating Expert Number and Rank for LoRA-MoE via Bilevel Optimization with GuidedSelection Vectors

Fuente: arXiv
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Autores principales: Zhang, Hengyuan, Chen, Xinrong, Qiu, Yingmin, Liang, Xiao, Li, Ziyue, Wang, Guanyu, Li, Weiping, Mo, Tong, So, Hayden Kwok-Hay, Wong, Ngai
Formato: Preprint
Publicado: 2025
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author Zhang, Hengyuan
Chen, Xinrong
Qiu, Yingmin
Liang, Xiao
Li, Ziyue
Wang, Guanyu
Li, Weiping
Mo, Tong
So, Hayden Kwok-Hay
Wong, Ngai
author_facet Zhang, Hengyuan
Chen, Xinrong
Qiu, Yingmin
Liang, Xiao
Li, Ziyue
Wang, Guanyu
Li, Weiping
Mo, Tong
So, Hayden Kwok-Hay
Wong, Ngai
contents Parameter-efficient fine-tuning (PEFT) methods, particularly Low-Rank Adaptation (LoRA), offer an efficient way to adapt large language models with reduced computational costs. However, their performance is limited by the small number of trainable parameters. Recent work combines LoRA with the Mixture-of-Experts (MoE), i.e., LoRA-MoE, to enhance capacity, but two limitations remain in hindering the full exploitation of its potential: 1) the influence of downstream tasks when assigning expert numbers, and 2) the uniform rank assignment across all LoRA experts, which restricts representational diversity. To mitigate these gaps, we propose GuiLoMo, a fine-grained layer-wise expert numbers and ranks allocation strategy with GuidedSelection Vectors (GSVs). GSVs are learned via a prior bilevel optimization process to capture both model- and task-specific needs, and are then used to allocate optimal expert numbers and ranks. Experiments on three backbone models across diverse benchmarks show that GuiLoMo consistently achieves superior or comparable performance to all baselines. Further analysis offers key insights into how expert numbers and ranks vary across layers and tasks, highlighting the benefits of adaptive expert configuration. Our code is available at https://github.com/Liar406/Gui-LoMo.git.
format Preprint
id arxiv_https___arxiv_org_abs_2506_14646
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle GuiLoMo: Allocating Expert Number and Rank for LoRA-MoE via Bilevel Optimization with GuidedSelection Vectors
Zhang, Hengyuan
Chen, Xinrong
Qiu, Yingmin
Liang, Xiao
Li, Ziyue
Wang, Guanyu
Li, Weiping
Mo, Tong
So, Hayden Kwok-Hay
Wong, Ngai
Computation and Language
Parameter-efficient fine-tuning (PEFT) methods, particularly Low-Rank Adaptation (LoRA), offer an efficient way to adapt large language models with reduced computational costs. However, their performance is limited by the small number of trainable parameters. Recent work combines LoRA with the Mixture-of-Experts (MoE), i.e., LoRA-MoE, to enhance capacity, but two limitations remain in hindering the full exploitation of its potential: 1) the influence of downstream tasks when assigning expert numbers, and 2) the uniform rank assignment across all LoRA experts, which restricts representational diversity. To mitigate these gaps, we propose GuiLoMo, a fine-grained layer-wise expert numbers and ranks allocation strategy with GuidedSelection Vectors (GSVs). GSVs are learned via a prior bilevel optimization process to capture both model- and task-specific needs, and are then used to allocate optimal expert numbers and ranks. Experiments on three backbone models across diverse benchmarks show that GuiLoMo consistently achieves superior or comparable performance to all baselines. Further analysis offers key insights into how expert numbers and ranks vary across layers and tasks, highlighting the benefits of adaptive expert configuration. Our code is available at https://github.com/Liar406/Gui-LoMo.git.
title GuiLoMo: Allocating Expert Number and Rank for LoRA-MoE via Bilevel Optimization with GuidedSelection Vectors
topic Computation and Language
url https://arxiv.org/abs/2506.14646