[Doc] Add LTX-2 online serving deployment recipes with optimization benchmarks (#1971)

Signed-off-by: samithuang <285365963@qq.com>
Signed-off-by: Samit <285365963@qq.com>

docs/user_guide/examples/online_serving/text_to_video.md

@@ -3,17 +3,28 @@
 Source <https://github.com/vllm-project/vllm-omni/tree/main/examples/online_serving/text_to_video>.
 
 
-This example demonstrates how to deploy the Wan2.2 text-to-video model for online video generation using vLLM-Omni.
+This example demonstrates how to deploy text-to-video models for online video generation using vLLM-Omni.
 
-## Start Server
+## Supported Models
 
-### Basic Start
+| Model | Model ID |
+|-------|----------|
+| Wan2.1 T2V (1.3B) | `Wan-AI/Wan2.1-T2V-1.3B-Diffusers` |
+| Wan2.1 T2V (14B) | `Wan-AI/Wan2.1-T2V-14B-Diffusers` |
+| Wan2.2 T2V | `Wan-AI/Wan2.2-T2V-A14B-Diffusers` |
+| LTX-2 | `Lightricks/LTX-2` |
+
+## Wan2.2 T2V
+
+### Start Server
+
+#### Basic Start
 
 ```bash
 vllm serve Wan-AI/Wan2.2-T2V-A14B-Diffusers --omni --port 8091
 ```
 
-### Start with Parameters
+#### Start with Parameters
 
 Or use the startup script:
 
@@ -234,8 +245,94 @@ while true; do
 done
 ```
 
+## LTX-2
+
+### Start Server
+
+#### Basic Start
+
+```bash
+vllm serve Lightricks/LTX-2 --omni --port 8098 \
+    --enforce-eager --flow-shift 1.0 --boundary-ratio 1.0
+```
+
+#### Start with Optimization Presets
+
+Use the LTX-2 startup script with built-in optimization presets:
+
+```bash
+# Baseline (1 GPU, eager)
+bash run_server_ltx2.sh baseline
+
+# 4-GPU Ulysses sequence parallelism (lossless)
+bash run_server_ltx2.sh ulysses4
+
+# Cache-DiT lossy acceleration (1 GPU, ~1.4× speedup)
+bash run_server_ltx2.sh cache-dit
+
+# Best combo: 4-GPU Ulysses SP + Cache-DiT (~2.2× speedup)
+bash run_server_ltx2.sh best-combo
+```
+
+#### Optimization Benchmarks
+
+Benchmarked on H800, online serving (480×768, 41 frames, 20 steps, `seed=42`).
+"Inference" is the server-reported inference time; excludes HTTP/poll overhead.
+
+| Preset | Server Command | Inference (s) | Speedup | Type |
+|--------|---------------|---------------|---------|------|
+| `baseline` | `--enforce-eager` | 10.3 | 1.00× | — |
+| `compile` | *(default, no --enforce-eager)* | ~10.3 (warm) | ~1.00× | Lossless |
+| `ulysses4` | `--enforce-eager --usp 4` | ~10.3 | ~1.00× | Lossless |
+| `cache-dit` | `--enforce-eager --cache-backend cache_dit` | 7.4 avg | ~1.4× | Lossy |
+| `best-combo` | `--enforce-eager --usp 4 --cache-backend cache_dit` | 4.7 avg | **~2.2×** | Lossless + Lossy |
+
+**Observations**:
+- **torch.compile**: On H800, warm-request inference time matches the eager baseline (~10.3s).
+  The first request pays ~6s compilation overhead. Benefit depends on model architecture and GPU.
+- **Ulysses SP (4 GPU)**: No measurable speedup alone for 41-frame generation at this resolution.
+  Communication overhead outweighs gains at this sequence length.
+- **Cache-DiT**: Inference varies per request (6–10s) due to dynamic caching decisions.
+  Average is ~7.4s (~1.4× speedup) with slight quality tradeoff.
+- **Best combo**: 4-GPU Ulysses SP + Cache-DiT synergize well — Cache-DiT reduces per-step
+  computation, making the communication overhead of Ulysses SP worthwhile. Average ~4.7s
+  (~2.2× speedup).
+- **FP8 quantization**: Reduces VRAM but does not speed up LTX-2 on H800 (compute-bound).
+
+**Deployment Recommendations**:
+- For **production with quality priority**: use `baseline` with `--enforce-eager`
+- For **maximum throughput** (4 GPUs, quality tradeoff): use `best-combo` (~2.2× speedup)
+- For **single-GPU throughput**: use `cache-dit` (~1.4× speedup)
+- `--enforce-eager` is recommended to avoid torch.compile warmup latency on first request
+
+### Send Requests (curl)
+
+```bash
+# Using the provided script
+bash run_curl_ltx2.sh
+
+# Or directly
+curl -sS -X POST http://localhost:8098/v1/videos \
+  -H "Accept: application/json" \
+  -F "prompt=A serene lakeside sunrise with mist over the water." \
+  -F "width=768" \
+  -F "height=480" \
+  -F "num_frames=41" \
+  -F "fps=24" \
+  -F "num_inference_steps=20" \
+  -F "guidance_scale=3.0" \
+  -F "seed=42"
+```
+
 ## Example materials
 
+??? abstract "response.json"
+    ``````json
+    --8<-- "examples/online_serving/text_to_video/response.json"
+    ``````
+??? abstract "run_curl_ltx2.sh"
+    ``````sh
+    --8<-- "examples/online_serving/text_to_video/run_curl_ltx2.sh"
 ??? abstract "run_curl_hunyuan_video_15.sh"
     ``````sh
     --8<-- "examples/online_serving/text_to_video/run_curl_hunyuan_video_15.sh"
@@ -248,6 +345,9 @@ done
     ``````sh
     --8<-- "examples/online_serving/text_to_video/run_server.sh"
     ``````
+??? abstract "run_server_ltx2.sh"
+    ``````sh
+    --8<-- "examples/online_serving/text_to_video/run_server_ltx2.sh"
 ??? abstract "run_server_hunyuan_video_15.sh"
     ``````sh
     --8<-- "examples/online_serving/text_to_video/run_server_hunyuan_video_15.sh"