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# Gemma 3 with Variable Sliding Window Attention

This guide demonstrates how to deploy google/gemma-3-1b-it with Variable Sliding Window Attention (VSWA) using Dynamo. Since google/gemma-3-1b-it is a small model, each aggregated, decode, or prefill worker only requires one H100 GPU or one GB200 GPU.
VSWA is a mechanism in which a model’s layers alternate between multiple sliding window sizes. An example of this is Gemma 3, which incorporates both global attention layers and sliding window layers.

> [!Note]
> - Ensure that required services such as `nats` and `etcd` are running before starting.
> - Request access to `google/gemma-3-1b-it` on Hugging Face and set your `HF_TOKEN` environment variable for authentication.
> - It's recommended to continue using the VSWA feature with the Dynamo 0.5.0 release and the TensorRT-LLM dynamo runtime image nvcr.io/nvidia/ai-dynamo/tensorrtllm-runtime:0.5.0. The 0.5.1 release bundles TensorRT-LLM v1.1.0rc5, which has a regression that breaks VSWA.

## Aggregated Serving
```bash
cd $DYNAMO_HOME/examples/backends/trtllm
export MODEL_PATH=google/gemma-3-1b-it
export SERVED_MODEL_NAME=$MODEL_PATH
export AGG_ENGINE_ARGS=$DYNAMO_HOME/examples/backends/trtllm/engine_configs/gemma3/vswa_agg.yaml
./launch/agg.sh
```

## Aggregated Serving with KV Routing
```bash
cd $DYNAMO_HOME/examples/backends/trtllm
export MODEL_PATH=google/gemma-3-1b-it
export SERVED_MODEL_NAME=$MODEL_PATH
export AGG_ENGINE_ARGS=$DYNAMO_HOME/examples/backends/trtllm/engine_configs/gemma3/vswa_agg.yaml
./launch/agg_router.sh
```

## Disaggregated Serving
```bash
cd $DYNAMO_HOME/examples/backends/trtllm
export MODEL_PATH=google/gemma-3-1b-it
export SERVED_MODEL_NAME=$MODEL_PATH
export PREFILL_ENGINE_ARGS=$DYNAMO_HOME/examples/backends/trtllm/engine_configs/gemma3/vswa_prefill.yaml
export DECODE_ENGINE_ARGS=$DYNAMO_HOME/examples/backends/trtllm/engine_configs/gemma3/vswa_decode.yaml
./launch/disagg.sh
```

## Disaggregated Serving with KV Routing
```bash
cd $DYNAMO_HOME/examples/backends/trtllm
export MODEL_PATH=google/gemma-3-1b-it
export SERVED_MODEL_NAME=$MODEL_PATH
export PREFILL_ENGINE_ARGS=$DYNAMO_HOME/examples/backends/trtllm/engine_configs/gemma3/vswa_prefill.yaml
export DECODE_ENGINE_ARGS=$DYNAMO_HOME/examples/backends/trtllm/engine_configs/gemma3/vswa_decode.yaml
./launch/disagg_router.sh
```
