Mixture-of-experts (MoE) is gaining increasing attention due to its unique
properties and remarkable performance, especially for language tasks. By
sparsely activating a subset of parameters for each token, MoE architecture
could increase the model size without sacrificing computational efficiency,
achieving a better trade-off between performance and training costs. However,
the underlying mechanism of MoE still lacks further exploration, and its
modularization degree remains questionable. In this paper, we make an initial
attempt to understand the inner workings of MoE-based large language models.
Concretely, we comprehensively study the parametric and behavioral features of
three recent MoE-based models and reveal some intriguing observations,
including (1) Neurons act like fine-grained experts. (2) The router of MoE
usually selects experts with larger output norms. (3) The expert diversity
increases as the layer increases, while the last layer is an outlier. Based on
the observations, we also provide suggestions for a broad spectrum of MoE
practitioners, such as router design and expert allocation. We hope this work
could shed light on future research on the MoE framework and other modular
architectures. Code is available at
this https URL

Mixture-of-experts (MoE) 的内在机制及行为特征的初步研究表明神经元如同细粒度专家，在参数和行为特征方面带来了一些有趣的观察，为 MoE 框架和其他模块化架构的未来研究提供了启示。