Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsity
In deep learning, models typically reuse the same parameters for all inputs.
Mixture of Experts (MoE) defies this and instead selects different parameters
for each incoming example. The result is a sparsely-activated model -- with
outrageous numbers of parameters -- but a constant computational cost. However,
despite several notable successes of MoE, widespread adoption has been hindered
by complexity, communication costs and training instability -- we address these
with the Switch Transformer. We simplify the MoE routing algorithm and design
intuitive improved models with reduced communication and computational costs.
Our proposed training techniques help wrangle the instabilities and we show
large sparse models may be trained, for the first time, with lower precision
(bfloat16) formats. We design models based off T5-Base and T5-Large to obtain
up to 7x increases in pre-training speed with the same computational resources.
These improvements extend into multilingual settings where we measure gains
over the mT5-Base version across all 101 languages. Finally, we advance the
current scale of language models by pre-training up to trillion parameter
models on the "Colossal Clean Crawled Corpus" and achieve a 4x speedup over the