While most attention logits can be computed in low precision without degrading numerical stability, current attention kernels fail to exploit this phenomenon.
We introduce a novel hardware-algorithm co-design in the form of mixed-precision FlashAttention.
Our method accumulates key-query products and evaluates their exponentials in 8-bit formats, then adaptively identifies sensitive sub-blocks and recomputes them in 16-bit formats.
We propose the specifications for a dedicated accelerator capable of executing this pipeline efficiently.
Simulated experiments with Qwen3 and Gemma 3 show that rerouting a selective minority of sub-blocks to high precision is sufficient to recover the baseline model performance.