What is vLLM?
vLLM is a high-throughput and memory-efficient inference and serving engine for LLMs. It is designed to serve LLMs at production scale with high concurrency and low latency.
Why vLLM?
The core innovation is PagedAttention — a memory management algorithm that allows serving more concurrent requests by managing GPU KV-cache memory like an OS manages RAM pages. This means:
- 24x higher throughput than naive HuggingFace serving on the same hardware.
- Continuous batching — new requests join an in-flight batch as slots free up.
- Efficient memory — near-zero memory waste on KV cache.
Key Features
- OpenAI-compatible API — drop-in replacement for OpenAI's API server.
- Streaming — supports streaming token output.
- Multi-GPU — tensor parallelism across multiple GPUs.
- Many models — supports LLaMA, Mistral, Mixtral, Falcon, MPT, GPT-2, T5, and more.
- Quantization — AWQ, GPTQ, SqueezeLLM.
Quick Start
pip install vllm
python -m vllm.entrypoints.openai.api_server --model meta-llama/Meta-Llama-3-8B-Instruct
vs. Ollama
Ollama is for personal use on a laptop. vLLM is for serving LLMs to many users with enterprise-grade throughput. Choose vLLM when you're building a product that needs to serve hundreds of concurrent requests.