Mixture of Experts layers (MoEs) enable efficient scaling of language models through conditional computation. This paper presents a detailed empirical study of how autoregressive MoE language models scale in comparison with dense models in a wide range of settings: in- and out-of-domain language modeling, zero- and few-shot priming, and full-shot fine-tuning. With the exception of fine-tuning, we find MoEs to be substantially more compute efficient. At more modest training budgets, MoEs can match the performance of dense models using ∼4 times less compute. This gap narrows at scale, but our largest MoE model (1.1T parameters) consistently outperforms a compute-equivalent dense model (6.7B parameters). Overall, this performance gap varies greatly across tasks and domains, suggesting that MoE and dense models generalize differently in ways that are worthy of future study. We make our code and models publicly available for research use.
Notes: Table 1
Size Notes: 112B tokens, or 84B words at 0.75 English words/token. "We pretrain our models on a union of six Englishlanguage datasets, including the five datasets used to pretrain RoBERTa (Liu et al., 2019) and the English subset of CC100, totalling 112B tokens" ... "All models are trained for 300B tokens with a sequence length of 2048 tokens."