arXiv
Aug 04, 2026
Test-Time Scaling in Reasoning LLMs: Inference Regimes, Evaluation, and Reproducibility
This preprint argues that test-time scaling should be evaluated as a complete inference system rather than a single compute budget. It distinguishes sequential, leaf-level, and prefix-level search regimes; sets out protocol-matched reporting and reproducibility requirements; and releases a corpus of more than two billion reasoning traces with progressively richer signals.
- The authors distinguish three structural regimes for test-time scaling: sequential single-trajectory, leaf-level with terminal reduction, and prefix-level scaling.
- The paper proposes evaluation and reproducibility requirements that treat the inference protocol as part of the evaluated system.
Why it mattersFor AI-product teams and investors, increasing inference spend is not a comparable performance lever unless the search procedure, verifier, compute accounting, and uncertainty reporting are specified. The paper offers a framework for separating real system improvements from reporting artifacts; its conclusions remain preprint evidence.
arXiv
Aug 04, 2026
Cross-Model KV Cache Transfer in LLM Families: A Closed-Form Linear Mapping for Prefill Reuse
The authors study reusing a source model's KV cache when a production system switches to a different model size within the same family. Across six pairs in three model families, their linear mapper retained 73–98% of the target model's standalone-prefill accuracy on four pairs and ran 2.7–25 times faster than re-prefill; two pairs degraded sharply and required a nonlinear fallback for recovery.
- The proposed method maps KV state across compatible model sizes to avoid repeating the target model's prefill after a routing or handoff decision.
- In the authors' six-pair evaluation, four pairs retained 73–98% of standalone-prefill accuracy, while two degraded sharply.
Why it mattersModel routers and cost-quality cascades often lose latency savings when a handoff forces a new prefill. This is a promising systems result for serving economics, but the results are model-pair-specific preprint evidence—not a validated production saving across vendors or workloads.