What is cuDNN implementation of rnn cells in Tensorflow

Question

To create RNN cells, there are classes like GRUCell and LSTMCell which can be used later to create RNN layers.
And also there are 2 other classes as CudnnGRU and CudnnLSTM which can be directly used to create RNN layers.

In the documentation they say that the latter classes have cuDNN implementation. Why should I use or not use this cuDNN implemented classes over classical RNN implementations when I'm creating a RNN model..?

Answer 1

In short: cudnnGRU and cudnnLSTM can/ must be used on GPU, normal rnn implementations not. So if you have tensorflow-gpu, cudnn implementation of RNN cells would run faster.