VLLM

Table of Contents Introduction Why Inference Optimization Matters The vLLM Architecture at a Glance 3.1 Dynamic Paging and Memory Management 3.2 Scheduler and Batch Fusion Identifying Bottlenecks in Standard LLM Serving Custom Kernel Development: When and How 5.1 Choosing the Right Kernel to Accelerate 5.2 CUDA Basics for LLM Engineers Hands‑On: Building a CUDA Kernel for Multi‑Head Attention 6.1 Reference Implementation in PyTorch 6.2 Porting to CUDA: Step‑by‑Step 6.3 Integrating the Kernel with vLLM Performance Evaluation 7.1 Benchmark Setup 7.2 Results and Analysis Production‑Ready Deployment Tips Future Directions & Community Roadmap Conclusion Resources Introduction Large language models (LLMs) have moved from research curiosities to production‑grade services that power chatbots, code assistants, and knowledge‑base search. While the training phase often dominates headlines, the inference phase is where cost, latency, and user experience converge. A single request to a 70‑billion‑parameter model can consume multiple gigabytes of GPU memory and stall a server for seconds if not carefully engineered. ...

Table of Contents Introduction Why Inference Optimization Matters Fundamentals of Quantization 3.1 Floating‑Point vs Fixed‑Point Representations 3.2 Common Quantization Schemes 3.3 Quantization‑Aware Training vs Post‑Training Quantization Practical Quantization Workflows for LLMs 4.1 Using 🤗 Transformers + BitsAndBytes 4.2 GPTQ & AWQ: Fast Approximate Quantization 4.3 Exporting to ONNX & TensorRT Benchmarking Quantized Models 5.1 Latency, Throughput, and Memory Footprint 5.2 Accuracy Trade‑offs: Perplexity & Task‑Specific Metrics Introducing vLLM: High‑Performance LLM Serving 6.1 Core Architecture and Scheduler 6.2 GPU Memory Management & Paging Deploying Quantized Models with vLLM 7.1 Installation & Environment Setup 7.2 Running a Quantized Model (Example: LLaMA‑7B‑4bit) 7.3 Scaling Across Multiple GPUs & Nodes Advanced Strategies: Mixed‑Precision, KV‑Cache Compression, and Async I/O Real‑World Case Studies 9.1 Customer Support Chatbot at a FinTech Startup 9.2 Semantic Search over Billion‑Document Corpus Best Practices & Common Pitfalls 11 Conclusion 12 Resources Introduction Large Language Models (LLMs) have transitioned from research curiosities to production‑grade engines powering chat assistants, code generators, and semantic search systems. Yet, the sheer size of state‑of‑the‑art models—often exceeding dozens of billions of parameters—poses a practical challenge: inference cost. ...

As an expert LLM infrastructure engineer, I’ve deployed countless inference systems where time-to-first-token (TTFT) and GPU efficiency make or break production performance. Enter LMCache—a game-changing KV cache layer that delivers 3-10x delay reductions by enabling “prefill-once, reuse-everywhere” semantics across serving engines like vLLM.[1][2] This zero-to-hero tutorial takes you from conceptual understanding to production deployment, covering architecture, integration, pitfalls, and real-world wins. Whether you’re building multi-turn chatbots or RAG pipelines, LMCache will transform your LLM serving stack. ...

Introduction vLLM has quickly become one of the most popular inference engines for serving large language models efficiently, thanks to its paged attention and strong OpenAI-compatible API. But as soon as you move beyond a single GPU or a single model server, you run into familiar infrastructure questions: How do I distribute traffic across multiple vLLM servers? How do I handle failures and keep latency predictable? How do I roll out new model versions without breaking clients? This is where the vLLM Router comes in. ...

Introduction If you’re trying to serve large language models (LLMs) efficiently on GPUs, you quickly run into a wall: GPU memory gets eaten by KV cache Throughput collapses as concurrent users increase You spend more on hardware than on your actual application vLLM is an open-source inference engine designed to fix this. It combines: A highly optimized attention implementation (PagedAttention) Continuous batching and scheduling A production-ready API server (OpenAI-compatible) Tight GPU memory management This tutorial is a concise zero-to-hero guide for developers who want to: ...