Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsity

Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsity

23 (2022) 1-40 | William Fedus*, Barret Zoph*, Noam Shazeer
The paper introduces the Switch Transformer, a sparsely-activated model that simplifies and improves upon the Mixture of Experts (MoE) paradigm. The Switch Transformer reduces computational complexity and communication costs while maintaining or improving model performance. Key contributions include: 1. **Simplified Sparse Routing**: The Switch Transformer uses a single expert per token, reducing router computation and batch size, and simplifying the routing implementation. 2. **Efficient Sparse Routing**: The model is designed for efficient distributed data and model parallel architectures, using Mesh-Tensorflow to facilitate sharding and load balancing. 3. **Training Techniques**: The paper addresses training instability and communication costs by introducing selective precision techniques and smaller parameter initialization. 4. **Scaling Properties**: The Switch Transformer demonstrates superior scaling properties, achieving faster training and better sample efficiency compared to dense models. 5. **Downstream Results**: The model shows significant improvements on various natural language processing tasks, including fine-tuning and multi-task learning. 6. **Model Design**: The paper explores different scaling strategies, including data, model, and expert-parallelism, to balance FLOPs, communication costs, and memory usage. 7. **Trillion Parameter Models**: The authors pre-train large sparse models up to 1.6 trillion parameters on the "Colossal Clean Crawled Corpus," achieving a 4x speedup over the T5-XXL model. The Switch Transformer is designed to be more computationally efficient and stable, making it suitable for training large-scale models with fewer resources.The paper introduces the Switch Transformer, a sparsely-activated model that simplifies and improves upon the Mixture of Experts (MoE) paradigm. The Switch Transformer reduces computational complexity and communication costs while maintaining or improving model performance. Key contributions include: 1. **Simplified Sparse Routing**: The Switch Transformer uses a single expert per token, reducing router computation and batch size, and simplifying the routing implementation. 2. **Efficient Sparse Routing**: The model is designed for efficient distributed data and model parallel architectures, using Mesh-Tensorflow to facilitate sharding and load balancing. 3. **Training Techniques**: The paper addresses training instability and communication costs by introducing selective precision techniques and smaller parameter initialization. 4. **Scaling Properties**: The Switch Transformer demonstrates superior scaling properties, achieving faster training and better sample efficiency compared to dense models. 5. **Downstream Results**: The model shows significant improvements on various natural language processing tasks, including fine-tuning and multi-task learning. 6. **Model Design**: The paper explores different scaling strategies, including data, model, and expert-parallelism, to balance FLOPs, communication costs, and memory usage. 7. **Trillion Parameter Models**: The authors pre-train large sparse models up to 1.6 trillion parameters on the "Colossal Clean Crawled Corpus," achieving a 4x speedup over the T5-XXL model. The Switch Transformer is designed to be more computationally efficient and stable, making it suitable for training large-scale models with fewer resources.
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