Meta's Jagged Flash Attention kernel beats FA4 on Blackwell using TLX
AIPyTorch Blog says its Jagged Flash Attention kernel, the attention kernel behind Meta's Generative Ads Model, runs on NVIDIA B200 Blackwell built with TLX (Triton Low-level Extensions). The kernel is about 3.2K lines, roughly 3× less code than the roughly 10K-line CuteDSL FlashAttention-4 (FA4) kernel, and outperforms FA4 (May 2026 version) on GEM's jagged shapes by about 13% on the forward pass and about 50% on the backward pass.








