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AI Systems

Notes on training, inference, and product co-design—connecting hardware and models to latency, cost, and user experience.

Current focus

Apple silicon

Exploring how Apple silicon architecture, compilers, and GPU kernels shape model execution.

Writing

15 articles · Newest first
LLM inference

LLM Generative watermarks

Who uses text watermarks, how generative watermarking works, and what it changes in an inference system.

GPU architecture

Apple GPU Evolution for AI Compute

Apple GPU evolution for AI compute, from Dynamic Caching and Neural Accelerators to the TensorOps and MLX software stack.

GPU kernels

Hopper kernel for MXFP4

Notes on Triton's Hopper MXFP4 matmul path, from packed FP4 unpacking into BF16 to scale conversion with inline PTX.

NCCL

Build PyTorch with NCCL2

Covers NCCL2 installation, clean PyTorch source builds, multi-GPU all-reduce tests, and network interface troubleshooting.

Tensor internals

Figure out what b.add_(b) has done

Traces PyTorch tensor addition from Python bindings through ATen, TH tensor macros, BLAS paths, OpenMP splitting, and AVX2 vector kernels.