Merging Experts into One: Improving Computational Efficiency of Mixture of Experts

Shwai He, Run-Ze Fan, Liang Ding, Li Shen, Tianyi Zhou, Dacheng Tao


Abstract
Scaling the size of language models usually leads to remarkable advancements in NLP tasks. But it often comes with a price of growing computational cost. Although a sparse Mixture of Experts (MoE) can reduce the cost by activating a small subset of parameters (e.g., one expert) for each input, its computation escalates significantly if increasing the number of activated experts, limiting its practical utility. Can we retain the advantages of adding more experts without substantially increasing the computational costs? In this paper, we first demonstrate the superiority of selecting multiple experts and then propose a computation-efficient approach called Merging Experts into One (MEO), which reduces the computation cost to that of a single expert. Extensive experiments show that MEO significantly improves computational efficiency, e.g., FLOPS drops from 72.0G of vanilla MoE to 28.6G (MEO). Moreover, we propose a token-level attention block that further enhances the efficiency and performance of token-level MEO, e.g., 83.3% (MEO) vs. 82.6% (vanilla MoE) average score on the GLUE benchmark. Our code will be released upon acceptance. Code will be released at: https://github.com/Shwai-He/MEO.
Anthology ID:
2023.emnlp-main.907
Volume:
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing
Month:
December
Year:
2023
Address:
Singapore
Editors:
Houda Bouamor, Juan Pino, Kalika Bali
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
14685–14691
Language:
URL:
https://aclanthology.org/2023.emnlp-main.907
DOI:
10.18653/v1/2023.emnlp-main.907
Bibkey:
Cite (ACL):
Shwai He, Run-Ze Fan, Liang Ding, Li Shen, Tianyi Zhou, and Dacheng Tao. 2023. Merging Experts into One: Improving Computational Efficiency of Mixture of Experts. In Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing, pages 14685–14691, Singapore. Association for Computational Linguistics.
Cite (Informal):
Merging Experts into One: Improving Computational Efficiency of Mixture of Experts (He et al., EMNLP 2023)
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PDF:
https://aclanthology.org/2023.emnlp-main.907.pdf
Video:
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