Building a FlashAttention-2 Forward Kernel in Pure NumPy
TL;DR — FlashAttention-2 is an IO-aware attention algorithm that fuses the softmax and matrix multiply into tiled CUDA kernels. We rebuild the forward pass from scratch in pure NumPy: blocking the QKV matrices into tiles, running a streaming softmax per block, and rescaling outputs online. The result is a runnable, testable side project that demonstrates memory-hierarchy thinking, numerical stability, and GPU-style programming patterns — exactly what hiring managers look for on a CV. ...