[Feat] Enable DiT tensor parallel for Diffusion Pipeline(Z-Image) (#735)

Signed-off-by: dongbo910220 <1275604947@qq.com>
Signed-off-by: dongbo910220 <32610838+dongbo910220@users.noreply.github.com>
Signed-off-by: Jiangyun Zhu <riverclouds.zhu@qq.com>
Co-authored-by: Jiangyun Zhu <riverclouds.zhu@qq.com>
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dongbo910220andJiangyun Zhu authored and GitHub committed 2026-01-12 11:00:42 +08:00
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@@ -12,27 +12,56 @@ The following parallelism methods are currently supported in vLLM-Omni:
3. Classifier-Free-Guidance Parallel (CFG-Parallel): CFG-Parallel runs the positive/negative prompts of classifier-free guidance (CFG) on different devices, then merges on a single device to perform the scheduler step.
4. [Tensor Parallelism](#tensor-parallelism): Tensor parallelism shards model weights across devices. This can reduce per-GPU memory usage. Note that for diffusion models we currently shard the majority of layers within the DiT.
The following table shows which models are currently supported by parallelism method:
### ImageGen
| Model | Model Identifier | Ulysses-SP | Ring-SP |CFG-Parallel |
|-------|------------------|-----------|-------------|-------------|
| **LongCat-Image** | `meituan-longcat/LongCat-Image` | ❌ | ❌ | ❌ |
| **LongCat-Image-Edit** | `meituan-longcat/LongCat-Image-Edit` | ❌ | ❌ | ❌ |
| **Ovis-Image** | `OvisAI/Ovis-Image` | ❌ | ❌ | ❌ |
| **Qwen-Image** | `Qwen/Qwen-Image` | ✅ | ✅ | ✅ |
| **Qwen-Image-Edit** | `Qwen/Qwen-Image-Edit` | ✅ | ✅ | ✅ |
| **Qwen-Image-Edit-2509** | `Qwen/Qwen-Image-Edit-2509` | ✅ | ✅ | ✅ |
| **Qwen-Image-Layered** | `Qwen/Qwen-Image-Layered` | ✅ | ✅ | ✅ |
| **Z-Image** | `Tongyi-MAI/Z-Image-Turbo` | ❌ | ❌ | ❌ |
| **Stable-Diffusion3.5** | `stabilityai/stable-diffusion-3.5` | ❌ | ❌ | ❌ |
| Model | Model Identifier | Ulysses-SP | Ring-SP | CFG-Parallel | Tensor-Parallel |
|-------|------------------|------------|---------|--------------|--------------------------|
| **LongCat-Image** | `meituan-longcat/LongCat-Image` | ❌ | ❌ | ❌ | ❌ |
| **LongCat-Image-Edit** | `meituan-longcat/LongCat-Image-Edit` | ❌ | ❌ | ❌ | ❌ |
| **Ovis-Image** | `OvisAI/Ovis-Image` | ❌ | ❌ | ❌ | ❌ |
| **Qwen-Image** | `Qwen/Qwen-Image` | ✅ | ✅ | ✅ | ❌ |
| **Qwen-Image-Edit** | `Qwen/Qwen-Image-Edit` | ✅ | ✅ | ✅ | ❌ |
| **Qwen-Image-Edit-2509** | `Qwen/Qwen-Image-Edit-2509` | ✅ | ✅ | ✅ | ❌ |
| **Qwen-Image-Layered** | `Qwen/Qwen-Image-Layered` | ✅ | ✅ | ✅ | ❌ |
| **Z-Image** | `Tongyi-MAI/Z-Image-Turbo` | ❌ | ❌ | ❌ | ✅ (TP=2 only) |
| **Stable-Diffusion3.5** | `stabilityai/stable-diffusion-3.5` | ❌ | ❌ | ❌ | ❌ |
!!! note "Why Z-Image is TP=2 only"
Z-Image Turbo is currently limited to `tensor_parallel_size` of **1 or 2** due to model shape divisibility constraints.
For example, the model has `n_heads=30` and a final projection out dimension of `64`, so valid TP sizes must divide both 30 and 64; the only common divisors are **1 and 2**.
### VideoGen
| Model | Model Identifier | Ulysses-SP | Ring-SP |
|-------|------------------|-----------|---------|
| **Wan2.2** | `Wan-AI/Wan2.2-T2V-A14B-Diffusers` | ❌ | ❌ |
| Model | Model Identifier | Ulysses-SP | Ring-SP | Tensor-Parallel |
|-------|------------------|------------|---------|--------------------------|
| **Wan2.2** | `Wan-AI/Wan2.2-T2V-A14B-Diffusers` | ❌ | ❌ | ❌ |
### Tensor Parallelism
Tensor parallelism splits model parameters across GPUs. In vLLM-Omni, tensor parallelism is configured via `DiffusionParallelConfig.tensor_parallel_size`.
#### Offline Inference
```python
from vllm_omni import Omni
from vllm_omni.diffusion.data import DiffusionParallelConfig
omni = Omni(
model="Tongyi-MAI/Z-Image-Turbo",
parallel_config=DiffusionParallelConfig(tensor_parallel_size=2),
)
outputs = omni.generate(
prompt="a cat reading a book",
num_inference_steps=9,
width=512,
height=512,
)
```
### Sequence Parallelism