Implementation Matters in Deep RL: A Case Study on PPO and TRPO

Reinforcement Learning


  • Logan Engstrom
  • Andrew Ilyas
  • Shibani Santurkar
  • Dimitris Tsipras
  • Firdaus Janoos
  • Larry Rudolph
  • Aleksander Madry

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We study the roots of algorithmic progress in deep policy gradient algorithms through a case study on two popular algorithms: Proximal Policy Optimization (PPO) and Trust Region Policy Optimization (TRPO). Specifically, we investigate the consequences of “code-level optimizations:” algorithm augmentations found only in implementations or described as auxiliary details to the core algorithm. Seemingly of secondary importance, such optimizations turn out to have a major impact on agent behavior. Our results show that they (a) are responsible for most of PPO’s gain in cumulative reward over TRPO, and (b) fundamentally change how RL methods function. These insights show the difficulty, and importance, of attributing performance gains in deep reinforcement learning.

Please cite our work using the BibTeX below.

title={Implementation Matters in Deep RL: A Case Study on PPO and TRPO},
author={Logan Engstrom and Andrew Ilyas and Shibani Santurkar and Dimitris Tsipras and Firdaus Janoos and Larry Rudolph and Aleksander Madry},
booktitle={International Conference on Learning Representations},
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