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nemo-mbridge-perf-moe-long-contextlisted

Long-context MoE training guidance for Megatron Bridge. Covers CP sizing, selective recompute, dispatcher choices, and practical patterns from DSV3, Qwen3, and Qwen3-Next long-context experiments.
yangwhale/CloseCrab · ★ 4 · AI & Automation · score 80
Install: claude install-skill yangwhale/CloseCrab
# MoE Long-Context Training Stable docs: @docs/training/moe-optimization.md Card: @skills/nemo-mbridge-perf-moe-long-context/card.yaml ## What Changes At Long Context Once sequence length moves well past the 4K-class regime, attention memory and activation residency become the dominant constraints. For MoE models, that usually means you need some combination of: - context parallelism - selective recompute - lower precision - CPU offload for optimizer state - a dispatcher and PP layout that do not waste the smaller remaining DP budget ## Rounded Scaling Patterns ### DSV3 on H100 The DSV3 long-context runs show a stable pattern: - selective recompute works better than full recompute once you move past the shortest contexts - throughput stays in a fairly narrow band from mid-length through very long contexts if CP is increased appropriately - the trade shifts from "memory fit" to "GPU-count feasibility" as CP grows In other words, long context does not immediately collapse utilization if the layout is chosen well, but it does consume the DP budget very quickly. ### Qwen3-Next on GB200 Qwen3-Next behaves more like a memory-sensitive medium-scale model: - 8K and 32K remain practical with moderate CP - 64K is possible, but the throughput drop is noticeable and memory becomes much tighter - pipeline layout and grouped-GEMM improvements matter almost as much as CP ### Qwen3 235B on GB200 Qwen3 235B shows that long context can still be efficient on NVL72 systems wh