arXiv:2504.05586cs.LGcs.AI2025-04被引 16

提出系统方法提升稀疏专家模型的效率与性能,解决专家冗余和能力丢失问题。

Finding Fantastic Experts in MoEs: A Unified Study for Expert Dropping Strategies and Observations

  • 构建专家重要性评估套件,多角度识别可裁剪专家
  • 采用迭代裁剪+任务无关微调,显著降低性能损失
  • 发现指令遵循能力易受损,可通过少量示例恢复

稀疏激活的专家混合模型(SMoE)在提升神经网络容量方面展现潜力,但存在专家冗余和内存开销大等问题,影响其在资源受限场景下的效率与可扩展性。本文针对三个核心问题展开研究:如何精准识别对性能影响最小的可裁剪专家子集?应采用一次性还是迭代式裁剪策略?如何通过修正机制缓解裁剪对子网络能力的冲击?首先,提出MoE专家压缩套件(MC-Suite),整合多种专家重要性评估方法,提供全面基准并揭示诸多洞见。其次,不同于以往的一次性裁剪,探索迭代裁剪结合MC-Suite准则重估的优越性,并引入任务无关微调作为校正手段,形成‘MoE彩票子网络’。最后,实验验证一个猜想:裁剪会严重损害SMoE的指令遵循能力,但可通过k-shot示例和监督微调有效恢复至稳健水平。

原文摘要 · Abstract (English)

Sparsely activated Mixture-of-Experts (SMoE) has shown promise in scaling up the learning capacity of neural networks. However, vanilla SMoEs have issues such as expert redundancy and heavy memory requirements, making them inefficient and non-scalable, especially for resource-constrained scenarios. Expert-level sparsification of SMoEs involves pruning the least important experts to address these limitations. In this work, we aim to address three questions: (1) What is the best recipe to identify the least knowledgeable subset of experts that can be dropped with minimal impact on performance? (2) How should we perform expert dropping (one-shot or iterative), and what correction measures can we undertake to minimize its drastic impact on SMoE subnetwork capabilities? (3) What capabilities of full-SMoEs are severely impacted by the removal of the least dominant experts, and how can we recover them? Firstly, we propose MoE Experts Compression Suite (MC-Suite), which is a collection of some previously explored and multiple novel recipes to provide a comprehensive benchmark for estimating expert importance from diverse perspectives, as well as unveil numerous valuable insights for SMoE experts. Secondly, unlike prior works with a one-shot expert pruning approach, we explore the benefits of iterative pruning with the re-estimation of the MC-Suite criterion. Moreover, we introduce the benefits of task-agnostic fine-tuning as a correction mechanism during iterative expert dropping, which we term MoE Lottery Subnetworks. Lastly, we present an experimentally validated conjecture that, during expert dropping, SMoEs' instruction-following capabilities are predominantly hurt, which can be restored to a robust level subject to external augmentation of instruction-following capabilities using k-shot examples and supervised fine-tuning.

专家混合模型压缩高效训练指令遵循

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