why flash can't accelerate on A40 machine?

[zhangxihou]

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Hi i tested flash-attn operation on an A40 machine and it showed no improvement on trainning speed , Moreover , I printed out the time cost of self-attention calculation part between two models . One model used normal attention , the other used flash-attn. Aart from that ,these two models are consistent. So can flash-atten only accelerate trainning speed on A100, but A40 can't? by the way,flash-atten did reduce the cuda memory usage! paste the env and other configurations: work: speech recognition env: cuda12.1 torch2.1.2 flash-atten 2.5.2
models: 11*conformers operation used: flash_attn_qkvpacked_func

[tridao]

Please benchmark just the attention operation