commit 86e3e008e084b37af3b579a0b6c03940d1d9446e
author Aapo Kyrola <akyrola@fb.com> Mon Oct 30 11:50:26 2017 -0700
committer Facebook Github Bot <facebook-github-bot@users.noreply.github.com> Mon Oct 30 12:24:12 2017 -0700
tree d84f8ddbbdb57130404e5b1984b73a2d6767ea1d
parent b7a9f51de31aa7e291a8aabc0f8a3073b8cf4697

optimize RNN executor subnet construction for forward-only models

Summary:
RNN executor had a disadvantage to plain nets when running in forward-only mode: for plain nets, we only create two workspaces and two nets and alternate between them. With RNN executor, we had only four workspaces (4 > 2 because it was faster in some cases), but the nets (or rather the ops) were created for each of the timesteps. This has significant overhead. This diff changes this sos that if executor is is forward-only mode (i.e has limited parallelism setting), then it will use the same operators as the t - 4'th net -- excluding the ops that require the timestep blob. The latter exception is required because RNN executor needs different timestep blob for each timestep because it cannot modify the value of the timestep blob like when running nets in a loop.

Also removed redundancy in the dependency computation and added a debug flag to the executor that outputs the description of the rnn contents.

Reviewed By: salexspb

Differential Revision: D6155510

fbshipit-source-id: c47f727d2128649b081270d15020a08d41e5748d