[GitHub] [incubator-mxnet] zixuanweeei commented on a change in pull request #17075: [MKLDNN] mkldnn RNN operator enhancement

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zixuanweeei commented on a change in pull request #17075: [MKLDNN] mkldnn RNN operator enhancement
URL: https://github.com/apache/incubator-mxnet/pull/17075#discussion_r358067041
 
 

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 File path: docs/static_site/src/pages/api/faq/env_var.md
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 @@ -349,6 +349,10 @@ If ctypes is used, it must be `mxnet._ctypes.ndarray.NDArrayBase`.
   - Values: 0(false) or 1(true) ```(default=1)```
   - If this variable is set, MXNet will simplify the computation graph, eliminating duplicated operations on the same inputs.
 
+* MXNET_USE_MKLDNN_RNN
+  - Values: 0(false) or 1(true) ```(default=1)```
+  - This variable controls whether to use the MKL-DNN backend in fused RNN operator for CPU context. There are two fusion implementations of RNN operator in MXNet. The MKL-DNN implementation has a better performance than the naive one, but the latter is more stable in the backward operation currently.
 
 Review comment:
   I think it is not stable in the backward pass. I have trained the bucketing model (https://github.com/apache/incubator-mxnet/tree/master/example/rnn/bucketing) with the backend of MKL-DNN RNN Backward. It resulted in a convergent optimizing curve. But it has not been tested in other applications for training a model. So I provided an env variable for users to switch to the naive implementation.

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