.. _input_processing_pipeline:

Input Processing Pipeline
=========================

1. Input data is passed to :class:`~vllm.LLMEngine` (or :class:`~vllm.AsyncLLMEngine`).

2. Tokenize the data if necessary.

3. Process the inputs using :meth:`INPUT_REGISTRY.process_input <vllm.inputs.registry.InputRegistry.process_input>`.

   - For example, add placeholder tokens to reserve KV cache for multi-modal embeddings.

4. Send the processed inputs to :class:`~vllm.executor.executor_base.ExecutorBase`.

5. Distribute the inputs via :class:`~vllm.worker.worker_base.WorkerBase` to :class:`~vllm.worker.model_runner_base.ModelRunnerBase`.

6. If the data contains multi-modal data, convert it into keyword arguments using :meth:`MULTIMODAL_REGISTRY.map_input <vllm.multimodal.MultiModalRegistry.map_input>`.

   - For example, convert a :class:`PIL.Image.Image` input to its pixel values for a vision language model.
