Purpose

Deploy and optimize LLM inference servers using vLLM, TGI, or Ollama with proper batching, quantization, and resource management.

When to use this skill

• deploying a model with vLLM or TGI for production inference
• configuring continuous batching and max concurrent requests
• fitting models into GPU memory with quantization (AWQ, GPTQ, GGUF)
• benchmarking throughput (tokens/sec) and latency (TTFT, TPS)

Do not use this skill when

• choosing which model to use — prefer model-selection
• running on CPU only — prefer offline-cpu-inference
• building agent memory or RAG — prefer agent-memory or embeddings-indexing

Procedure

1. Choose serving framework — vLLM for high-throughput GPU serving, TGI for HuggingFace models, Ollama for local dev.
2. Select quantization — AWQ/GPTQ for GPU (4-bit, minimal quality loss), GGUF for llama.cpp/CPU. Match quant to VRAM budget.
3. Launch server — vllm serve <model> --tensor-parallel-size <gpus> --max-model-len <ctx> --quantization awq.
4. Configure batching — vLLM uses continuous batching by default. Set --max-num-seqs to control concurrency.
5. Set memory limits — --gpu-memory-utilization 0.9 for vLLM. Reserve 10% for KV cache overhead.
6. Add OpenAI-compatible API — vLLM and TGI both serve /v1/chat/completions. Point clients at http://localhost:8000.
7. Benchmark — python -m vllm.entrypoints.openai.api_server --benchmark or use locust/hey for load testing.
8. Monitor — track GPU utilization (nvidia-smi), request queue depth, TTFT (time to first token), and throughput.

vLLM deployment

# Basic serving
pip install vllm
vllm serve meta-llama/Llama-3.1-8B-Instruct \
  --tensor-parallel-size 1 \
  --max-model-len 8192 \
  --gpu-memory-utilization 0.9

# With quantization (fits larger models in less VRAM)
vllm serve TheBloke/Llama-3.1-70B-AWQ \
  --quantization awq \
  --tensor-parallel-size 2 \
  --max-model-len 4096

TGI deployment

docker run --gpus all -p 8080:80 \
  -v /data:/data \
  ghcr.io/huggingface/text-generation-inference:latest \
  --model-id meta-llama/Llama-3.1-8B-Instruct \
  --max-batch-total-tokens 32768 \
  --max-input-tokens 4096

GPU memory estimation

Model params * bytes per param = VRAM needed
  7B  * 2 bytes (fp16)  = ~14 GB
  7B  * 0.5 bytes (4bit) = ~3.5 GB + KV cache
  70B * 2 bytes (fp16)  = ~140 GB (2x A100 80GB)
  70B * 0.5 bytes (4bit) = ~35 GB + KV cache

Decision rules

• Use vLLM for production GPU serving — best throughput via PagedAttention.
• Use Ollama for local development and testing — simplest setup.
• AWQ quantization for GPU, GGUF for CPU — do not mix formats.
• Set max-model-len to actual max needed, not model max — saves KV cache memory.
• Always benchmark with realistic request patterns before deploying.

References

• https://docs.vllm.ai/
• https://huggingface.co/docs/text-generation-inference/
• https://ollama.com/

Related skills

• model-selection — choosing the right model
• llama-cpp — CPU/hybrid inference with llama.cpp
• offline-cpu-inference — CPU-only optimization