Dive into FlashAttention-3
The rise of large language models has made the “attention” mechanism a cornerstone of modern AI. But attention is computationally and memory-intensive, often becoming a bottleneck. Enter FlashAttention, a groundbreaking algorithm designed to accelerate this crucial step. While the cutting-edge FlashAttention-4 for NVIDIA’s new Blackwell architecture is now emerging, understanding the leap forward made by FlashAttention-3 on the widely-used Hopper (H100) platform is key to grasping modern GPU optimization. This post will dissect the clever combination of techniques that make it fast, from algorithmic innovations like the fused kernel to the deep hardware co-design on Hopper, which uses specialized units like the Tensor Memory Accelerator (TMA) to power advanced scheduling patterns like Warp Specialization and Pingpong Scheduling. ...