4-bit量化推理模型在测试时动态扩增,解决误判提前停止问题。
BitCal-TTS: Bit-Calibrated Test-Time Scaling for Quantized Reasoning Models
- 设计轻量级运行时控制器,结合不确定性和推理稳定性在线估算。
- 在512个词元上限下,7B和14B模型准确率分别提升3.7和2.8点。
- 无需微调模型,适配主流4比特推理框架,适合资源受限场景。
后训练量化使大模型在内存与延迟约束下具备实用性,但会扭曲驱动自适应测试时计算分配的在线信号。在新生成词元数固定的情况下,信心失准可能导致有害的过早终止:模型可能呈现看似合理的最终答案,而底层推理仍错误;或控制器在推理轨迹未稳定前就停止。本文针对贪心4比特推理研究该问题,提出BitCal-TTS——一种轻量级运行时控制器,包含(i)低成本的词元级不确定性与推理轨迹稳定性在线代理,(ii)低精度下保守的比特条件置信度重校准,(iii)面向GSM8K类结构化输出的比特感知后标记确认窗口。方法无需微调基模型,通过前向钩子集成至标准Hugging Face 4比特推理流程。在小规模GSM8K评估片段上(7B: N=54, 14B: N=35),BitCal-TTS在7B和14B模型上均优于非比特感知基线,准确率提升+3.7和+2.8点,过早停止率从14.8%降至11.1%(7B)、17.1%降至11.4%(14B)。全程报告威尔逊95%置信区间,并明确讨论部分片段比较的统计效力有限。代码与绘图脚本已开源以支持复现。
原文摘要 · Abstract (English)
Post-training quantization makes large reasoning models practical under tight memory and latency budgets, but it can distort the online signals that drive adaptive test-time compute allocation. Under a fixed cap on the number of newly generated tokens, miscalibrated confidence can lead to harmful early halting: the model may surface a plausible final line while the underlying reasoning is still wrong, or the controller may stop before the trace has stabilized. We study this interaction for greedy 4-bit inference and propose BitCal-TTS, a lightweight runtime controller that combines (i) inexpensive online proxies for token-level uncertainty and reasoning-trace stability, (ii) a bit-conditioned confidence rescaling that is conservative at low nominal precision, and (iii) a bit-aware post-marker confirmation horizon designed for GSM8K-style structured outputs. The method requires no fine-tuning of the base model and integrates with standard Hugging Face 4-bit inference using forward hooks for logits and last-layer hidden states. On small evaluation shards of GSM8K with Qwen2.5 Instruct models, BitCal-TTS improves exact-match accuracy over a non-bit-aware adaptive baseline at the 7B and 14B scales while preserving substantial token savings relative to fixed-budget decoding. At a token cap of B=512, on the evaluation shards we report (N=54 for 7B and N=35 for 14B; not the full GSM8K test set), accuracy gains are +3.7 points (7B) and +2.8 points (14B), with the premature-stop rate falling from 14.8% to 11.1% on 7B and from 17.1% to 11.4% on 14B. We report Wilson 95% confidence intervals throughout and explicitly discuss the limited statistical power of the partial-shard comparisons. We release code and figure-generation scripts to support full reproduction.
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