Domyn scales 1T MoE training to 1,300 tokens/s per GPU on JUPITER using TorchTitan

·2026.11.14 01:28

Key point

The team optimized FSDP and Expert Parallelism on 384 GH200 GPUs to reach 1,300 tokens/s per GPU, overcoming inter-node bandwidth bottlenecks.

Details

  • Achieved 1,300 tokens/s per GPU throughput for a ~1T-parameter MoE on 384 GH200 GPUs, a 14x improvement over the initial baseline.
  • Utilized 384-way FSDP and 4-way Expert Parallelism (EP) within nodes to minimize cross-node communication, leveraging the 900 GB/s Grace-Hopper C2C link for activation offloading.
  • Reduced optimizer step time from 42 seconds to ~2 seconds by running Newton-Schulz iterations on the GPU instead of the CPU, contributing to a 35% throughput increase.
  • Implemented FP8 expert all-gather and node-local resharding to cut communication volume, resulting in an 18% gain without affecting training loss.
  • Fixed memory allocator issues by moving allocations to the compute stream, eliminating retries and boosting throughput by 21% while reducing peak reserved memory by 13.5 GiB.
  • Model and training recipes are planned for open release, with all fixes contributed upstream to PyTorch and TorchTitan.

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