@mgouicem Just to confirm few things:

1. Your idea is to fuse dropout to rnn primitives (https://oneapi-src.github.io/oneDNN/group__cpp__api__rnn.html) as post-op or attribute ? Correct ?
2. Currently in frameworks dropout is implemented as two elementwise (binary) operations. As I see https://oneapi-src.github.io/oneDNN/v2.0-beta03/dev_guide_attributes_post_ops.html post-ops are not defined for rnn primitives. You mentioned "then this limits the usage of some primitives, typically RNNs". I just wanted from you to confirm statement: "Currently RNNs are also limited because binary is not fused with them" ?

@piotrchmiel ,
sorry should have been clearer on the dropout attribute idea.
Some primitive need to apply dropout between two computations internally (e.g. if we fuse layers/iteration in RNN, we might have to apply the dropout between layers/iterations inside the primitive execution).
If we offer only a dropout primitive, a user can no more fuse layers/iterations in the RNN primitive if they need to apply dropout.
So we will have to have an attribute eventually to support it for RNN (or any other primitive where applying dropout would prevent fusion). Note that it is not a post-op per se since it happens in the middle of the computation for RNN, not at the end.
Now, the suggestion is, why not introduce such an attribute right now, so that we have only one mechanism to support dropout instead of two (a standalone primitive + an attribute)?

@mgouicem Ok, so if I understand correctly you're proposing attribute instead of post-ops, because you want to enable fused operation not only at the end of execution of the primitive, but also possibly in the middle where applicable.

1. How it is implemented now ? For example if you need dropout in the middle of RNN primitive execution, how you deal with that ? You simply don't use RNN primitives ?
2. Why do you think standalone primitive is obsolete not complementary to attribute approach? Attribute will require injecting implementation of dropout in all primitives where user wants to apply it. As you mentioned sometimes somewhere in the middle, sometimes at the end. Attribute allows possible the best fuse method, but it requires implementation of injection inside all primitives where we will identify that user may wants to use dropout. What if the user wanted to use dropout in other than we identified ? Standalone primitive will allow him to do that.