Writing Speed-of-Light Flash Attention for 5090 in CUDA C++

In this post, I will walkthrough how I learned to implement Flash Attention for 5090 in CUDA C++. The main objective is to learn writing attention in CUDA C++, since many features are not available in Triton , such as MXFP8 / NVFP4 MMA for sm120. I also feel this is a natural next step after learning about matmul kernels. Lastly, there are many excellent blogposts on writing fast matmul kernels,…