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Documentation Index

Fetch the complete documentation index at: https://docs.sglang.io/llms.txt

Use this file to discover all available pages before exploring further.

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1. Model Introduction

Qwen-Image is a text-to-image diffusion model developed by the Qwen team. For more details, please refer to the official Qwen-Image HuggingFace page, the Blog, and the Tech Report.

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2. SGLang-diffusion Installation

SGLang-diffusion offers multiple installation methods. You can choose the most suitable installation method based on your hardware platform and requirements. Please refer to the official SGLang-diffusion installation guide for installation instructions.

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3. Model Deployment

This section provides deployment configurations optimized for different hardware platforms and use cases.

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3.1 Basic Configuration

Qwen-Image is a text-to-image model. The recommended launch configurations vary by hardware. Interactive Command Generator: Use the configuration selector below to automatically generate the appropriate deployment command for your hardware platform.

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3.2 Configuration Tips

Current supported optimization all listed here.
  • --vae-path: Path to a custom VAE model or HuggingFace model ID (e.g., fal/FLUX.2-Tiny-AutoEncoder). If not specified, the VAE will be loaded from the main model path.
  • --num-gpus: Number of GPUs to use
  • --tp-size: Tensor parallelism size (only for the encoder; should not be larger than 1 if text encoder offload is enabled, as layer-wise offload plus prefetch is faster)
  • --sp-degree: Sequence parallelism size (typically should match the number of GPUs)
  • --ulysses-degree: The degree of DeepSpeed-Ulysses-style SP in USP
  • --ring-degree: The degree of ring attention-style SP in USP
AMD ROCm Notes: Requires SGLang >= v0.5.8.

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4. API Usage

For complete API documentation, please refer to the official API usage guide.

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4.1 Generate an Image

Example
import base64
from openai import OpenAI

client = OpenAI(api_key="EMPTY", base_url="http://localhost:30000/v1")

response = client.images.generate(
    model="Qwen/Qwen-Image",
    prompt="A logo With Bold Large text: SGL Diffusion",
    n=1,
    response_format="b64_json",
)

# Save the generated image
image_bytes = base64.b64decode(response.data[0].b64_json)
with open("output.png", "wb") as f:
    f.write(image_bytes)

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4.2 Advanced Usage

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4.2.1 Cache-DiT Acceleration

SGLang integrates Cache-DiT, a caching acceleration engine for Diffusion Transformers (DiT), to achieve up to 7.4x inference speedup with minimal quality loss. You can set SGLANG_CACHE_DIT_ENABLED=True to enable it. For more details, please refer to the SGLang Cache-DiT documentation. Basic Usage
Command
SGLANG_CACHE_DIT_ENABLED=true sglang serve --model-path Qwen/Qwen-Image
Advanced Usage
  • DBCache Parameters: DBCache controls block-level caching behavior:
ParameterEnv VariableDefaultDescription
FnSGLANG_CACHE_DIT_FN1Number of first blocks to always compute
BnSGLANG_CACHE_DIT_BN0Number of last blocks to always compute
WSGLANG_CACHE_DIT_WARMUP4Warmup steps before caching starts
RSGLANG_CACHE_DIT_RDT0.24Residual difference threshold
MCSGLANG_CACHE_DIT_MC3Maximum continuous cached steps
  • TaylorSeer Configuration: TaylorSeer improves caching accuracy using Taylor expansion:
ParameterEnv VariableDefaultDescription
EnableSGLANG_CACHE_DIT_TAYLORSEERfalseEnable TaylorSeer calibrator
OrderSGLANG_CACHE_DIT_TS_ORDER1Taylor expansion order (1 or 2)
Combined Configuration Example:
Command
SGLANG_CACHE_DIT_ENABLED=true \
SGLANG_CACHE_DIT_FN=2 \
SGLANG_CACHE_DIT_BN=1 \
SGLANG_CACHE_DIT_WARMUP=4 \
SGLANG_CACHE_DIT_RDT=0.4 \
SGLANG_CACHE_DIT_MC=4 \
SGLANG_CACHE_DIT_TAYLORSEER=true \
SGLANG_CACHE_DIT_TS_ORDER=2 \
sglang serve --model-path Qwen/Qwen-Image

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4.2.2 CPU Offload

  • --dit-cpu-offload: Use CPU offload for DiT inference. Enable if run out of memory.
  • --text-encoder-cpu-offload: Use CPU offload for text encoder inference.
  • --vae-cpu-offload: Use CPU offload for VAE.
  • --pin-cpu-memory: Pin memory for CPU offload. Only added as a temp workaround if it throws “CUDA error: invalid argument”.

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5. Benchmark

Test Environment:
  • Hardware: AMD Instinct MI300X GPU (1x)
  • Model: Qwen/Qwen-Image
  • Docker Image: lmsysorg/sglang:v0.5.8-rocm700-mi30x
  • sglang diffusion version: 0.5.8

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5.1 Speedup Benchmark

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5.1.1 Generate an image

Server Command:
Command
sglang serve --model-path Qwen/Qwen-Image \
    --ulysses-degree=1 --ring-degree=1 --port 30000
Benchmark Command:
Command
python3 -m sglang.multimodal_gen.benchmarks.bench_serving \
    --backend sglang-image --dataset vbench --task text-to-image --num-prompts 1 --max-concurrency 1
Result:
Output
================= Serving Benchmark Result =================
Task:                                    text-to-image
Model:                                   Qwen/Qwen-Image
Dataset:                                 vbench
--------------------------------------------------
Benchmark duration (s):                  29.04
Request rate:                            inf
Max request concurrency:                 1
Successful requests:                     1/1
--------------------------------------------------
Request throughput (req/s):              0.03
Latency Mean (s):                        29.0378
Latency Median (s):                      29.0378
Latency P99 (s):                         29.0378
--------------------------------------------------
Peak Memory Max (MB):                    48018.83
Peak Memory Mean (MB):                   48018.83
Peak Memory Median (MB):                 48018.83
============================================================

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5.1.2 Generate images with high concurrency

Benchmark Command:
Command
python3 -m sglang.multimodal_gen.benchmarks.bench_serving \
    --backend sglang-image --dataset vbench --task text-to-image --num-prompts 20 --max-concurrency 20
Result:
Output
================= Serving Benchmark Result =================
Task:                                    text-to-image
Model:                                   Qwen/Qwen-Image
Dataset:                                 vbench
--------------------------------------------------
Benchmark duration (s):                  300.79
Request rate:                            inf
Max request concurrency:                 20
Successful requests:                     14/20
--------------------------------------------------
Request throughput (req/s):              0.05
Latency Mean (s):                        154.5368
Latency Median (s):                      154.8363
Latency P99 (s):                         285.4603
--------------------------------------------------
Peak Memory Max (MB):                    48030.31
Peak Memory Mean (MB):                   48030.30
Peak Memory Median (MB):                 48030.29
============================================================