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name: parallel-and-optimization description: "Plans HunyuanVideo multi-GPU xDiT inference, FP8 command construction, memory trade-offs, and optional CUDA dependency troubleshooting." disable-model-invocation: true metadata: disco-role: operating license: NOASSERTION

HunyuanVideo Parallel and Optimization

Use this sub-skill when the user mentions multi-GPU generation, xDiT, torchrun, --ulysses-degree, --ring-degree, FP8 weights, flash-attn, xfuser, memory pressure, or CUDA backend errors.

Read first

• references/parallel-and-fp8.md for xDiT and FP8 command patterns.
• references/memory-and-backends.md for GPU memory and dependency planning.
• references/troubleshooting.md for xDiT, FP8, and flash-attn failures.
• scripts/build_optimized_command.py to build safe multi-GPU or FP8 commands without launching generation.

Command-builder examples

Multi-GPU xDiT command:

python sub-skills/parallel-and-optimization/scripts/build_optimized_command.py multi-gpu \
  --prompt "A cat walks on the grass, realistic style." \
  --height 720 --width 1280 --nproc-per-node 4 --ulysses-degree 2 --ring-degree 2

FP8 command:

python sub-skills/parallel-and-optimization/scripts/build_optimized_command.py fp8 \
  --prompt "A cat walks on the grass, realistic style." \
  --dit-weight ckpts/hunyuan-video-t2v-720p/transformers/mp_rank_00_model_states_fp8.pt

The helper validates degree products and FP8 map paths. It prints commands only; actual generation remains a GPU/model job.

Non-negotiable backend facts

• xDiT requires CUDA, NCCL, xfuser, and a valid torchrun world size.
• Distributed mode asserts --use-cpu-offload is false.
• --nproc_per_node must equal --ulysses-degree * --ring-degree.
• FP8 requires both the FP8 .pt weight and the derived _map.pt scale file.
• CPU imports do not verify xDiT or FP8 generation.