DDRL ablation: skipping SFT and running RL straight from pretraining works

gowthami_s · x · 2026-10-15

Parts 4-5 of the thread: the paper ablates skipping SFT since DDRL already includes a supervised loss. Removing the separate 20k-step SFT stage and running DDRL directly from pretraining on the same dataset yields comparable rewards and diffusion loss to SFT→DDRL — works in this setup, though the x-axis is data used and expensive RL rollouts still dominate compute. The author's own take: don't skip SFT; you still need good rollouts to do RL.

Related event: DDRL keeps diffusion loss during RL to fix reward hacking in video models(5 posts)→

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