You can login to Nvidia Developer, and look at the developer guide for Cudnn:
https://docs.nvidia.com/deeplearning/sdk/cudnn-developer-guide/index.html 15
All the functions for recurrent networks in cudnn requires a cudnnRNNDescriptor_t instance as input. When you initialize an RNN descriptor object with cudnnSetRNNDescriptor() function, you define the algorithm with cudnnRNNAlgo_t value, which can be CUDNN_RNN_ALGO_STANDARD, CUDNN_RNN_ALGO_PERSIST_STATIC, or CUDNN_RNN_ALGO_PERSIST_DYNAMIC.
You can refer to the cudnn developer guide for information.