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# BAGEL-7B-MoT
Source <https://github.com/vllm-project/vllm-omni/tree/main/examples/offline_inference/bagel>.
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## Set up
Please refer to the [stage configuration documentation](https://docs.vllm.ai/projects/vllm-omni/en/latest/configuration/stage_configs/) to configure memory allocation appropriately for your hardware setup.
## Run examples
**Note**: These examples work with the default configuration on an **NVIDIA A100 (80GB)**. We also tested on dual **NVIDIA RTX 5000 Ada (32GB each)**. For dual-GPU setups, please modify the stage configuration to distribute the model across devices.
Get into the bagel folder
```bash
cd examples/offline_inference/bagel
```
### Modality Control
BAGEL-7B-MoT supports multiple modality modes. You can control the mode using the `--modality` argument:
#### Text to Image (text2img)
- **Pipeline**: Text → Thinker → DiT → VAE Decode → Image
- **Stages Used**: Stage 0 (Thinker) + Stage 1 (DiT)
- **KV Transfer**: Thinker sends KV cache to DiT for conditioned generation
Generate images from text prompts:
```bash
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality text2img \
--prompts "A cute cat"
```
#### Image to Image (img2img)
- **Pipeline**: Image → VAE Encode → DiT → VAE Decode → New Image
- **Stages Used**: Stage 1 (DiT) only
- **Special**: Bypasses the Thinker stage, direct image-to-image transformation
Transform images based on text prompts:
```bash
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality img2img \
--image-path /path/to/image.jpg \
--prompts "Let the woman wear a blue dress"
```
#### Image to Text (img2text)
- **Pipeline**: Image → ViT + VAE Encode → Thinker → Text Output
- **Stages Used**: Stage 0 (Thinker) only
- **Special**: Uses both VAE latent encoding AND ViT semantic encoding for comprehensive image understanding
Generate text descriptions from images:
```bash
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality img2text \
--image-path /path/to/image.jpg \
--prompts "Describe this image in detail"
```
#### Text to Text (text2text)
- **Pipeline**: Text → Thinker → Text Output
- **Stages Used**: Stage 0 (Thinker) only
- **Special**: No visual components involved, operates as pure language model
Pure text generation:
```bash
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality text2text \
--prompts "What is the capital of France?"
# You can load prompts from a text file (one prompt per line):
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality text2text \
--txt-prompts /path/to/prompts.txt
```
### Inference Steps
Control the number of inference steps for image generation:
```bash
# You can adjust steps to 100 to improve image quality
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality text2img \
--steps 50 \
--prompts "A cute cat"
```
### Key arguments
BAGEL-7B-MoT supports **multiple modality modes** for different use cases.
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The default yaml configuration deploys Thinker and DiT on the same GPU. You can use the default configuration file: [`bagel.yaml`](https://github.com/vllm-project/vllm-omni/tree/main/vllm_omni/model_executor/stage_configs/bagel.yaml)
#### 📌 Command Line Arguments (end2end.py)
| Argument | Type | Default | Description |
| :--------------------- | :----- | :---------------------------- | :----------------------------------------------------------- |
| `--model` | string | `ByteDance-Seed/BAGEL-7B-MoT` | Model path or name |
| `--modality` | choice | `text2img` | Modality mode: `text2img`, `img2img`, `img2text`, `text2text` |
| `--prompts` | list | `None` | Input text prompts directly |
| `--txt-prompts` | string | `None` | Path to txt file with one prompt per line |
| `--image-path` | string | `None` | Input image path (for `img2img`/`img2text`) |
| `--steps` | int | `50` | Number of inference steps |
| `--stage-configs-path` | string | `None` | Custom stage config file path |
| `--worker-backend` | choice | `process` | Worker backend: `process` or `ray` |
| `--ray-address` | string | `None` | Ray cluster address |
| `--enable-stats` | flag | `False` | Enable statistics logging |
| `--init-sleep-seconds` | int | `20` | Initialization sleep time |
| `--batch-timeout` | int | `5` | Batch timeout |
| `--init-timeout` | int | `300` | Initialization timeout |
------
#### ⚙️ Stage Configuration Parameters (bagel.yaml)
**Stage 0 - Thinker (LLM Stage)**
| Parameter | Value | Description |
| :------------------------------- | :------------------------------ | :----------------------- |
| `stage_type` | `llm` | Stage type |
| `devices` | `"0"` | GPU device ID |
| `max_num_seqs` | `1` | Maximum batch size |
| `model_stage` | `thinker` | Model stage identifier |
| `model_arch` | `BagelForConditionalGeneration` | Model architecture |
| `gpu_memory_utilization` | `0.4` | GPU memory utilization |
| `tensor_parallel_size` | `1` | Tensor parallel size |
| `max_num_batched_tokens` | `32768` | Maximum batched tokens |
| `omni_kv_config.need_send_cache` | `true` | Whether to send KV cache |
------
**Stage 1 - DiT (Diffusion Stage)**
| Parameter | Value | Description |
| :------------------------------- | :---------- | :-------------------------- |
| `stage_type` | `diffusion` | Stage type |
| `devices` | `"0"` | GPU device ID |
| `max_num_seqs` | `1` | Maximum batch size |
| `model_stage` | `dit` | Model stage identifier |
| `gpu_memory_utilization` | `0.4` | GPU memory utilization |
| `omni_kv_config.need_recv_cache` | `true` | Whether to receive KV cache |
| `engine_input_source` | `[0]` | Input source from Stage 0 |
------
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#### Tensor Parallelism (TP)
For larger models or multi-GPU environments, you can enable Tensor Parallelism (TP) by modifying the stage configuration (e.g., [`bagel.yaml`](https://github.com/vllm-project/vllm-omni/tree/main/vllm_omni/model_executor/stage_configs/bagel.yaml)).
1. **Set `tensor_parallel_size`**: Increase this value (e.g., to `2` or `4`).
2. **Set `devices`**: Specify the comma-separated GPU IDs to be used for the stage (e.g., `"0,1"`).
Example configuration for TP=2 on GPUs 0 and 1:
```yaml
engine_args:
tensor_parallel_size: 2
...
runtime:
devices: "0,1"
```
------
#### 🔗 Runtime Configuration
| Parameter | Value | Description |
| :-------------------- | :------ | :------------------------------- |
| `shm_threshold_bytes` | `65536` | Shared memory threshold (64KB) |
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## Using Mooncake Connector
[Mooncake](https://github.com/kvcache-ai/Mooncake) is a high-performance distributed KV cache transfer engine that enables efficient cross-node data movement via TCP or RDMA, making it ideal for multi-node disaggregated inference.
By default, BAGEL uses `SharedMemoryConnector` for inter-stage communication. You can switch to the Mooncake connector for better performance on multi-GPU setups and to enable multi-node deployment.
### Prerequisites
Install the Mooncake transfer engine:
```bash
# For CUDA-enabled systems (recommended)
pip install mooncake-transfer-engine
# For non-CUDA systems
pip install mooncake-transfer-engine-non-cuda
```
### Step 1: Start the Mooncake Master
On the **primary node**, start the Mooncake master service (run in a separate terminal or background with `&`):
```bash
# Optional: enable disk-backed storage by creating a directory and passing --root_fs_dir.
# Without it, Mooncake runs in memory-only mode, which is sufficient for KV cache transfer.
mkdir -p ./mc_storage
mooncake_master \
--rpc_port=50051 \
--enable_http_metadata_server=true \
--http_metadata_server_host=0.0.0.0 \
--http_metadata_server_port=8080 \
--metrics_port=9003 \
--root_fs_dir=./mc_storage/ \
--cluster_id=mc-local-1 &
```
### Step 2: Run Offline Inference with Mooncake
Use the provided Mooncake stage config [`bagel_multiconnector.yaml`](https://github.com/vllm-project/vllm-omni/tree/main/vllm_omni/model_executor/stage_configs/bagel_multiconnector.yaml). Before launching, update the `metadata_server` and `master` addresses in the YAML to match your Mooncake master node's IP (use `127.0.0.1` for single-node testing).
```bash
cd examples/offline_inference/bagel
# Text to Image with Mooncake
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality text2img \
--prompts "A cute cat" \
--stage-configs-path ../../../vllm_omni/model_executor/stage_configs/bagel_multiconnector.yaml
# Image to Text with Mooncake
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality img2text \
--image-path /path/to/image.jpg \
--prompts "Describe this image" \
--stage-configs-path ../../../vllm_omni/model_executor/stage_configs/bagel_multiconnector.yaml
# Text to Text with Mooncake
python end2end.py --model ByteDance-Seed/BAGEL-7B-MoT \
--modality text2text \
--prompts "What is the capital of France?" \
--stage-configs-path ../../../vllm_omni/model_executor/stage_configs/bagel_multiconnector.yaml
```
For more details on the Mooncake connector and multi-node setup, see the [Mooncake Store Connector documentation](https://github.com/vllm-project/vllm-omni/tree/main/docs/design/feature/omni_connectors/mooncake_store_connector.md).
------
## FAQ
- If you don’t know how much VRAM is needed for the model or encounter the OOM error, you can try to decrease the max_model_len.
| Stage | VRAM |
| :------------------ | :--------------------------- |
| Stage-0 (Thinker) | **15.04 GiB** **+ KV Cache** |
| Stage-1 (DiT) | **26.50 GiB** |
| Total | **~42 GiB + KV Cache** |
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## Example materials
??? abstract "end2end.py"
``````py
--8<-- "examples/offline_inference/bagel/end2end.py"
``````