Agentic AI Notebook
Phase 21

vLLM

~2 min read

Concept & How It Works

  • Key points are in the visual diagram above.

Why Does It Exist?

Serving open-source models at scale needs optimized inference. vLLM is the default for production self-hosted LLMs.

Real-World Analogy

vLLM is a smart valet parking system — fits more cars (requests) in the same lot (GPU memory) without waste.
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Visual Workflows

What is vLLM?

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Example

Scenario

Serve Llama 3 8B on 1x L4 with vLLM — 3x higher throughput than naive HuggingFace generate loop.

Solution

In Agent Runtime & Production, apply vLLM to this scenario: Serve Llama 3 8B on 1x L4 with vLLM — 3x higher throughput than naive HuggingFace generate loop. Identify the inputs, run the technique, validate the output, and note one thing you would monitor in production.

Practice Task

Do this before moving to the next module — reading alone is not enough.

Open the Code Walkthrough below and run it locally. Change one parameter related to vLLM (e.g. model, temperature, top_k, or tool name), observe the difference in output, and write 2–3 sentences explaining what changed.

Code Walkthrough

Highlighted lines show where vLLM happens in the code.

vLLM
1python -m vllm.entrypoints.openai.api_server \  # key line for vLLM2  --model meta-llama/Llama-3.1-8B-Instruct \3  --port 8000

Commands to Remember

Commands to Remember

  • pip install fastapi uvicorn # serve agent APIs
  • docker build -t agent-api . # containerize for production
  • kubectl apply -f deployment.yaml # deploy to Kubernetes

Common Mistakes

  • Treating vLLM as a black box without evaluation
  • Ignoring cost and latency in production
  • Skipping error handling for vllm

Cheat Sheet

Quick recap — the most important points from this module.

Cheat Sheet

quick ref
  • vLLM
  • PagedAttention
  • Continuous Batching
  • KV Cache