Alexi

If you learn AI Infrastructure Engineering, you will never be unemployed again. Stage 1: Systems & GPU Foundations - Learn: C++, Rust, CUDA memory hierarchy, PCIe vs NVLink, thread blocks and warp scheduling. - Practice: Write a custom CUDA kernel for matrix multiplication from scratch and profile it against cuBLAS. - Why: You cannot optimize what you do not understand at the silicon level. Stage 2: Transformer Inference Physics - Learn: Prefill vs Decode phases, arithmetic intensity, memory bandwidth bottlenecks, KV-cache math. - Practice: Profile a HuggingFace model with Nsight Systems to identify the exact memory bottleneck during token generation. - Why: LLM inference is almost always memory-bound, not compute-bound. Stage 3: Modern Serving Engines & Batching - Learn: vLLM, SGLang, PagedAttention, continuous batching, chunked prefill. - Practice: Deploy a 70B model and tune chunk sizes to maximize throughput without starving decode requests during long-context prefills. - Why: Naive batching leaves 60% of GPU VRAM wasted. PagedAttention fixes this. Stage 4: KV-Cache & Memory Optimization - Learn: Prefix caching, KV quantization, CPU offloading, multi-turn cache reuse. - Practice: Build a routing proxy that directs requests with identical system prompts to the same replica to share KV blocks. - Why: Reused cache is free speed. It can slash Time-To-First-Token (TTFT) by 80%. Stage 5: Quantization & Compression - Learn: FP8, INT4, AWQ, GPTQ, Sparsity, TensorRT-LLM calibration. - Practice: Serve a model in FP8 vs FP16 and benchmark the exact perplexity drop against the latency and VRAM gains. - Why: Quantization is the only way to fit frontier models on edge GPUs and protect your margins. Stage 6: Kernel-Level Engineering - Learn: Triton, FlashAttention, CUDA graphs, operator fusion. - Practice: Write a fused Triton kernel for RMSNorm or Softmax and benchmark it against the native PyTorch implementation. - Why: Python overhead kills inference. Fused kernels save milliseconds that compound at scale. Stage 7: Distributed Inference & Parallelism - Learn: Tensor parallelism, Pipeline parallelism, Expert parallelism (for MoE models). - Practice: Shard a 405B parameter model across 8 nodes and measure the communication overhead between GPUs. - Why: Single-GPU inference is dead for frontier models. You must master the shard. Stage 8: Speculative Decoding - Learn: Draft-target models, Medusa heads, acceptance rates, n-gram drafting. - Practice: Build a pipeline where a local 3B model drafts tokens for a cloud 70B model to verify in parallel. - Why: 2x decode speed at zero quality cost is the closest thing to a free lunch in inference. Stage 9: Multi-Node & Hardware Interconnects - Learn: NCCL, RDMA, InfiniBand, NVLink, Disaggregated Prefill/Decode architectures. - Practice: Set up a multi-node cluster and profile the network latency of tensor parallelism across nodes vs within a single node. - Why: Network latency is the new GPU bottleneck. Disaggregating prefill and decode is the 2026 meta. Stage 10: Cluster Orchestration & GPU Scheduling - Learn: Kubernetes GPU operators, Ray, Slurm, MIG (Multi-Instance GPU) partitioning, KEDA. - Practice: Build a queue-based autoscaler that spins up spot GPUs based on pending inference requests and drains them when empty. - Why: Idle H100s burn $3+/hr. FinOps and scheduling are now core infra responsibilities. Stage 11: AI Gateways, Routing & Observability - Learn: TTFT/ITL SLOs, semantic routing, DCGM metrics, OpenTelemetry for LLMs. - Practice: Build a gateway that routes simple queries to a quantized local model and complex reasoning to a frontier API based on prompt complexity. - Why: Routing protects your margins and DCGM metrics tell you when your GPUs are silently throttling. Stage 12: Public Benchmarks & Teardowns - Learn: Reproducible methodology, latency/throughput Pareto curves, cost-per-token analysis. - Practice: Publish a teardown comparing vLLM vs SGLang vs TensorRT-LLM on your specific hardware with full configs. - Why: Public proof of hardware mastery gets you hired instantly by top AI labs. Wrappers are a commodity. AI Infrastructure is the physics of scale. The modern AI Infra Engineer builds the silicon nervous system for global intelligence. Bookmark and Repost!