Au Revoir Backprop! Bonjour Optical Transfer Learning!

Code used to produce data for our blog post Au Revoir Backprop! Bonjour Optical Transfer Learning!

Access to Optical Processing Units

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How to install

We advise creating a virtualenv before running these commands. You can create one with python3 -m venv <venv_name>. Activate it with source <path_to_venv>/bin/activate before proceeding. We used python 3.5 and pytorch 1.2 for all the simulations.

• Clone the repository and then do pip install <path_to_repo>.

• (optional) Should you wish to replicate the results with TensorRT in int8 you need to download the appropriate version from the official NVIDIA website. We tested the code with TensorRT 6.0.1.5 with CUDA 10.1.

• Finally download the dataset from the Kaggle page. You should put the dataset in the same folder as the repo, but all scripts have an option to change the path with -dataset_path.

NOTE: we had problems with the Pillow package because this combination of Pytorch and TensorRT requires version Pillow 6.1 in the onnx conversion of the model. If you have the same problems, uninstall Pillow and then retry with pip install Pillow==6.1.

Replicate the OPU/backprop results

Use the script multiple_block.sh in the bash folder. Open it in a text editor and then:

• set the OPU/backprop flags at the top to true, depending on which simulation you want to run

• Set the dtype to float32/float16. This affects only the OPU simulation.

• (optional) change the path to the script/dataset/save folder if you want to deviate from the defaults;

• launch ./multiple_block.sh. You might need to run chmod +x multiple_block.sh to make the script executable.

Jupyter notebook option

The notebook TL_OPU.ipynb in the notebooks folder does largely the same thing as the OPU script. It is a good way to get an idea of the general pipeline on the full DenseNet model.

Replicate the TensorRT results

Navigate to the script folder and then launch the following command:

python3 tensorrt_training.py densenet169 Saturn -dtype_train int8 -dtype_inf int8 -block 10 -layer 12 
-n_components 2 -encode_type plain_th -encode_thr 0 -alpha_exp_min 6 -alpha_exp_max 8 
-save_path ~/dummy/int8/ -features_path ~/datasets_conv_features/int8_features/

Substitute the save_path with your desired destination folder. In the above example I had pre-extracted the features on a GPU which supported int8 (RTX 2080) and then moved them to the OPU machine. If your machine already supports int8 just drop the -features_path argument.

If you want to just extract the dataset features you can use the tensorrt_extract_features.py. Example call:

python3 tensorrt_extract_features.py densenet169 32 -block 10 -layer 12 
-dtype_train int8 -dtype_inf int8 -dataset_path ~/datasets/animals10/

Obviously change the dataset path with the correct one on your machine.

Hardware specifics

All the simulations have been run on a Tesla P100 GPU with 16GB memory and a Intel(R) Xeon(R) Gold 6128 CPU @ 3.40GHz with 12 cores. For the int8 simulations we use an RTX 2080 with 12GB memory.