How to understand this on pytorch website?
I notice this on pytorch official website: https://pytorch.org/docs/stable/nn.html

If the following conditions are satisfied: 

1) cudnn is enabled, 

2) input data is on the GPU, 

3) input data has dtype torch.float16, 

4) V100 GPU is used, and

5) input data is not in PackedSequence format.

Then, persistent algorithm can be selected to improve performance.

Could anyone explain it? Thanks.

This refers a to very low level performance optimization of GPU cache usage, which is explained more in-depth here (note: this is not a PyTorch material, but I believe it does a good enough job at explaining). In other words, if all the bullets are satisfied, PyTorch will default to a different algorithm under the hood, hopefully providing higher RNN performance.
