Direct-OPD: Transferring RL Policy Shifts from Small to Large Models

_lewtun · x · 2026-08-12

The HF journal club discussed Direct On-Policy Distillation (Direct-OPD), a paper from a joint Tsinghua and ByteDance lab.

The method tackles the high cost of running Reinforcement Learning (RL) on large models. The core idea is to run expensive RL on a smaller model, extract the policy shift (the difference between pre-RL and post-RL checkpoints), and distill this shift into a larger, already stronger model.

Unlike naive distillation (which inherits the small model's limitations), transferring this RL-induced policy shift yields strong results. On AIME24, a 7B student model improved its score from 56.7 to 63.1 by absorbing the policy shift from a 1.5B teacher pair.

Related event: Tsinghua and ByteDance Propose Direct-OPD for Model Distillation(3 posts)→

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