St-moe: Designing Stable And Transferable Sparse Expert Models

Zoph Barret, Bello Irwan, Kumar Sameer, Du Nan, Huang Yanping, Dean Jeff, Shazeer Noam, Fedus William. Arxiv 2022

[Paper]    
Applications Fine Tuning Model Architecture Pretraining Methods Security Training Techniques Transformer

Scale has opened new frontiers in natural language processing – but at a high cost. In response, Mixture-of-Experts (MoE) and Switch Transformers have been proposed as an energy efficient path to even larger and more capable language models. But advancing the state-of-the-art across a broad set of natural language tasks has been hindered by training instabilities and uncertain quality during fine-tuning. Our work focuses on these issues and acts as a design guide. We conclude by scaling a sparse model to 269B parameters, with a computational cost comparable to a 32B dense encoder-decoder Transformer (Stable and Transferable Mixture-of-Experts or ST-MoE-32B). For the first time, a sparse model achieves state-of-the-art performance in transfer learning, across a diverse set of tasks including reasoning (SuperGLUE, ARC Easy, ARC Challenge), summarization (XSum, CNN-DM), closed book question answering (WebQA, Natural Questions), and adversarially constructed tasks (Winogrande, ANLI R3).

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