arXiv AI By Zhengxin Zhang, Maosen Tang, Ning Wang, Changhao Li, Jingren Zhou, Bo Dai, Sainyam Galhotra, Alex Townsend, Claire Cardie

Does On-Policy Distillation Need to Complete Every Rollout?

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The paper introduces Stochastic Truncated On-Policy Distillation (STOPD), a method that speeds up on-policy distillation by randomly truncating student rollouts and correcting sampling bias with blockwise inverse-probability weighting. STOPD retains teacher feedback for every generated token and preserves the expected gradient of vanilla OPD while providing theoretical error bounds for common optimizers. Experiments show that STOPD cuts generated tokens by 25–48% and achieves 1.3–2.2× faster training without sacrificing accuracy.

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