arXiv:2606.02288cs.LG2026-06

发现大模型激活峰值实为结构化向量偏置,提出无峰值量化方法。

Massive Spikes in LLMs are Bias Vectors: Mechanistic Uncovering and Spike-Free Quantization

论文配图:Massive Spikes in LLMs are Bias Vectors: Mechanistic Uncovering and Spike-Free Quantization
图 1 · 摘自论文原文
  • 激活峰值是归一化后恒定向量,驱动注意力与值态机制。
  • 提出INSERTQUANT框架,使激活严格无峰值,支持低比特量化。
  • 可泛化至视觉模型,性能媲美顶级张量量化方法。

大型语言模型(LLMs)中的大规模激活峰值会因动态范围拉伸而严重损害量化效果。尽管以往假设这些峰值是高层标量偏置,我们提出它们实际上是携带峰值的标记中刚性结构向量偏置的标量中间结果。我们发现这些标记在归一化后收敛到常定向量,驱动注意力汇聚和值状态耗尽机制。通过分析投影权重的协同作用:$W_K$ 对该向量进行对比增强,$W_Q$ 将语义标记对齐至其方向,$W_V$ 将其投影至谱零空间,从几何上证实了这一现象。此外,模型通过将这些结构偏置定位在“旋转稳定性区域”,利用低频带和相干通道对来主动抵御旋转位置编码(RoPE)扰动。基于此,我们提出INSERTQUANT——一种后训练量化(PTQ)框架,通过预计算模板向量钳制峰值并恢复其功能。该方法实现严格无峰值激活,支持鲁棒的低比特量化且保持高保真度。INSERTQUANT在LLMs上达到与最先进逐张量量化方法相当的性能,并独特地泛化至ViTs等其他模态。

原文摘要 · Abstract (English)

Massive activation spikes in Large Language Models (LLMs) severely degrade quantization by stretching dynamic ranges. While prior hypotheses characterize these as high-level scalar biases, we argue that they are merely the scalar intermediates of rigid, structural vector biases in the spike-carrying tokens. We show that these tokens converge to constant vectors after normalization that drive the attention sink and value-state drain mechanisms. We geometrically substantiate this by analyzing the coordination of projection weights: $W_K$ contrastively amplifies the vector, $W_Q$ aligns semantic tokens toward it, and $W_V$ projects it into the spectral null-space. Furthermore, we reveal that the model actively preserves these structural biases against Rotary Positional Embedding (RoPE) perturbations by localizing them in "zones of rotational stability" utilizing low-frequency bands and coherent channel pairs. Leveraging this, we propose INSERTQUANT, a post-training quantization (PTQ) framework that clamps spikes and restores their function via pre-computed template vectors. This renders activations strictly spike-free, enabling robust low-bit quantization with high fidelity. INSERTQUANT achieves parity with state-of-the-art per-tensor quantization methods on LLMs and uniquely generalizes beyond text to other modalities such as ViTs.

量化大模型注意力机制结构偏置

Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。