2022

MegaBlocks: Efficient Sparse Training with Mixture-of-Experts

Gale, Trevor, Narayanan, Deepak, Young, Cliff et al.

Understand

We present MegaBlocks, a system for efficient Mixture-of-Experts (MoE) training on GPUs.

  • Our system is motivated by the limitations of current frameworks, which restrict the dynamic routing in MoE layers to satisfy the constraints of existing software and hardware.
  • These formulations force a tradeoff between model quality and hardware efficiency, as users must choose between dropping tokens from the computation or wasting computation and memory on padding.
  • To address these limitations, we reformulate MoE computation in terms of block-sparse operations and develop new block-sparse GPU kernels that efficiently handle the dynamism present in MoEs.

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