Scaling LLM Inference with Custom CUDA Kernels and Distributed Memory Management
Table of Contents Introduction Why Scaling LLM Inference Is Hard 2.1 Memory Footprint 2.2 Compute Throughput 2.3 Latency vs. Batch Size Trade‑offs Fundamentals of CUDA for LLMs 3.1 Thread Hierarchy & Memory Types 3.2 Warp‑level Primitives 3.3 Common Pitfalls Designing Custom CUDA Kernels for Transformer Ops 4.1 Matrix‑Multiplication (GEMM) Optimizations 4.2 Fused Attention Kernel 4.3 Layer Normalization & Activation Fusion 4.4 Kernel Launch Configuration Best Practices Distributed Memory Management Strategies 5.1 Tensor Parallelism 5.2 Pipeline Parallelism 5.3 Hybrid Parallelism 5.4 Memory Swapping & Off‑loading Putting It All Together: A Full‑Stack Inference Pipeline 6.1 Data Flow Diagram 6.2 Implementation Sketch (Python + PyCUDA) 6.3 Performance Benchmarking Methodology Real‑World Case Studies 7.1 OpenAI’s “ChatGPT” Scaling Journey 7.2 Meta’s LLaMA‑2 Production Deployment 7.3 Start‑up Example: Low‑Latency Chatbot on a 4‑GPU Node Future Directions & Emerging Technologies 8.1 Tensor Cores Beyond FP16/BF16 8.2 NVidia Hopper & Transformer Engine 8.3 Unified Memory & NVLink‑based Hierarchical Memory Conclusion Resources Introduction Large language models (LLMs) have transitioned from research curiosities to production‑grade services that power chatbots, code assistants, and search engines. While training these models often dominates headlines, inference—the process of generating predictions from a trained model—poses its own set of engineering challenges. As model sizes balloon past 100 B parameters, a single forward pass can consume tens of gigabytes of GPU memory and require hundreds of teraflops of compute. ...