arXiv:2603.07365cs.LGcs.AI2026-03

小模型性能随规模变化规律首次被揭示,发现越小越准但错得不同。

Scaling Laws in the Tiny Regime: How Small Models Change Their Mistakes

  • 在22K至19.8M参数范围内测试90个模型,分析误差率与规模的幂律关系。
  • 小模型误差下降更快(指数α=0.106~0.156),但大到一定程度后性能饱和。
  • 小模型误判集中在简单样本,且校准性更好,不适合用大模型经验评估。

神经网络缩放定律描述了模型性能随规模提升的幂律关系,但现有研究主要针对超1亿参数的大模型。本文首次系统考察小于2000万参数的微型模型(即边缘计算场景):在CIFAR-100上训练90个模型(22K–19.8M参数),采用Plain ConvNet和MobileNetV2两种架构,固定深度与训练条件,仅调整宽度。结果表明,两类模型误差率均近似遵循幂律关系,对应指数分别为α=0.156±0.002(ScaleCNN)与α=0.106±0.001(MobileNetV2),比大型语言模型(α≈0.076)更陡峭。然而幂律并非全局成立:局部指数随规模衰减,且MobileNetV2在19.8M处出现饱和(局部指数α_local=0.006)。错误模式也显著变化:最小与最大规模模型的错误样本重叠率仅0.35(25组种子,±0.004),说明压缩改变了误判对象而非数量。小模型将能力集中于简单类别(吉尼系数0.26,22K参数时;4.7M时为0.09),放弃最难类别(底5类准确率:22K时10% → 4.7M时53%)。令人意外的是,最小模型校准最优(ECE=0.013,中等规模峰值达0.110)。因此,边缘部署时仅依赖聚合精度是误导性的,验证必须在目标模型尺寸进行。

原文摘要 · Abstract (English)

Neural scaling laws describe how model performance improves as a power law with size, but existing work focuses on models above 100M parameters. The sub-20M regime -- where TinyML and edge AI operate -- remains unexamined. We train 90 models (22K--19.8M parameters) across two architectures (plain ConvNet, MobileNetV2) on CIFAR-100, varying width while holding depth and training fixed. Both follow approximate power laws in error rate: $α= 0.156 \pm 0.002$ (ScaleCNN) and $α= 0.106 \pm 0.001$ (MobileNetV2) across five seeds. Since prior work fit cross-entropy loss rather than error rate, direct exponent comparison is approximate; with that caveat, these are 1.4--2x steeper than $α\approx 0.076$ for large language models. The power law does not hold uniformly: local exponents decay with scale, and MobileNetV2 saturates at 19.8M parameters ($α_{\mathrm{local}} = 0.006$). Error structure also changes. Jaccard overlap between error sets of the smallest and largest ScaleCNN is only 0.35 (25 seed pairs, $\pm 0.004$) -- compression changes which inputs are misclassified, not merely how many. Small models concentrate capacity on easy classes (Gini: 0.26 at 22K vs. 0.09 at 4.7M) while abandoning the hardest (bottom-5 accuracy: 10% vs. 53%). Counter to expectation, the smallest models are best calibrated (ECE = 0.013 vs. peak 0.110 at mid-size). Aggregate accuracy is therefore misleading for edge deployment; validation must happen at the target model size.

小模型缩放定律边缘计算错误模式

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