vLLM adaptive verification now works head-free, using draft logits with online logistic calibration

vllm_project · x · 2026-10-15

vLLM announces a major simplification to adaptive verification: it previously required a drafter with a trained confidence head, but now works with draft models you already serve—MTP, EAGLE, DFlash and DSpark checkpoints without a head, no retraining.

Key insight: the signal was already in the draft logits. The drafter's own top-token probability ranks drafts as well as a trained confidence head, but overestimates acceptance rates; a tiny logistic fit trained online from the target's accept/reject decisions corrects the calibration.

In benchmarks, a single adaptive verification config at max draft length stays on the throughput–interactivity Pareto frontier at most concurrencies with no per-load tuning. Available now on main behind enableadaptiveverification, for draft models whose attention backends support variable-length verification. Built by Giancarlo Delfin.

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