MoE Expert-Parallel Overlap Skill

References

• Stable docs: @docs/training/communication-overlap.md
• Structured metadata: @skills/nemo-mbridge-perf-expert-parallel-overlap/card.yaml

What It Is

Expert-parallel (EP) overlap hides the cost of token dispatch/combine all-to-all communication by running it concurrently with expert FFN compute. Optionally, delayed expert weight-gradient computation (delay_wgrad_compute) provides additional overlap by deferring wgrad to overlap with the next layer's forward.

Bridge supports two dispatcher paths: