Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/NVIDIA-NeMo/Megatron-Bridgenpx agentmods add skills/nvidia-nemo/megatron-bridge/nemo-mbridge-perf-moe-comm-overlapWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/nvidia-nemo/megatron-bridge/nemo-mbridge-perf-moe-comm-overlap)<a href="https://agentmods.dev/skills/nvidia-nemo/megatron-bridge/nemo-mbridge-perf-moe-comm-overlap"><img src="https://agentmods.dev/badge/skills/nvidia-nemo/megatron-bridge/nemo-mbridge-perf-moe-comm-overlap/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/nvidia-nemo/megatron-bridge/nemo-mbridge-perf-moe-comm-overlap"><img src="https://agentmods.dev/badge/skills/nvidia-nemo/megatron-bridge/nemo-mbridge-perf-moe-comm-overlap.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00042 | $0.01929 |
| Opus 5 | $0.00021 | $0.00964 |
| Sonnet 5 | $0.00008 | $0.00386 |
| Haiku 4.5 | $0.00004 | $0.00193 |
Grade A, and why
nemo-mbridge-perf-moe-comm-overlap scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
100% identical to nemo-mbridge-perf-moe-comm-overlap — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 189 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MoE Communication Overlap
For the higher-level overview, see:
- @docs/training/communication-overlap.md
- @skills/nemo-mbridge-perf-moe-comm-overlap/card.yaml
Quick Decision
Use MoE communication overlap when:
EP > 1- token dispatch or combine time is visible in the profile
- the run is already correct and you are now tuning throughput
Avoid turning it on as an early bring-up step. It is easier to validate after the dispatcher, routing mode, and recompute plan are already stable.
Enablement
cfg.comm_overlap.overlap_moe_expert_parallel_comm = True
# Optional: delayed wgrad for additional overlap
cfg.comm_overlap.delay_wgrad_compute = True
# IMPORTANT: disable shared expert overlap when using dispatch overlap
cfg.model.moe_shared_expert_overlap = False
Prerequisites
expert_model_parallel_size > 1num_moe_experts > 1moe_token_dispatcher_typemust be"alltoall"or"flex"- Precision: BF16 or FP16
- If PP is used, VPP (
virtual_pipeline_model_parallel_size) must be set (non-None)
Flex dispatcher activation
Setting moe_flex_dispatcher_backend alone does not activate flex dispatch.
You must also set moe_token_dispatcher_type = "flex".
Recompute And CUDA Graph Interaction
- Full recompute is not a good companion for the overlap path.
delay_wgrad_computeadds further constraints if CUDA-graph scopes include attention or MoE-router work.- In practice, selective recompute is the safer pairing when overlap is enabled.
Measured Evidence
HybridEP production-shape validation
A 2026-07-25 controlled Qwen3 30B-A3B pretraining comparison used 16 H100
GPUs, BF16, sequence length 4096, TP=1, PP=1, CP=1, EP=16,
MBS=1, GBS=1024, forced-balanced routing, HybridEP, and Transformer
Engine CUDA-graph scopes moe_router and moe_preprocess. The only
performance change was plain EP overlap; delayed wgrad stayed disabled.
| Case | Steady window | Step time | Model TFLOPS/GPU |
|---|---|---|---|
| EP overlap off | iterations 5-20 | 24.7138s | 244.039 |
| EP overlap on, search run | iterations 5-20 | 21.0725s | 286.208 |
| EP overlap on, independent validation | iterations 41-50 | 20.9920s | 287.305 |
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 189 lines · 42 tokens per session scan A 4a9656bdc898
nemo-mbridge-perf-moe-comm-overlap is a skill published in the GitHub repository NVIDIA-NeMo/Megatron-Bridge (905 stars, last pushed yesterday), licensed Apache-2.0. It adds 42 tokens to every session and 1,929 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to nemo-mbridge-perf-moe-comm-overlap, differing in 0 lines, and is treated as a copy.
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