arXiv:2601.04890cs.LG2026-01被引 1

让语言模型矩阵层自学习缩放系数,提升性能并减少调参负担。

Learnable Multipliers: Freeing the Scale of Language Model Matrix Layers

  • 为矩阵层引入可学习的缩放系数,替代固定权重衰减控制尺度。
  • 在多个数据集上实现优于标准muP基线的性能提升,尤其在下游任务中表现更优。
  • 适用于追求高精度与低调参成本的语言模型训练,适合研究者与工程师使用。

大型语言模型预训练中,对矩阵层施加权重衰减(WD)是标准做法。已有研究表明,随机梯度噪声会引发权重矩阵W的布朗运动式增长,其增长被WD抵消,形成一个固定的权重范数||W||的平衡态。本文认为该平衡范数是训练过程的有害副产物,提出引入可学习的缩放系数以自动学习最优尺度。首先,在矩阵W上附加可学习标量乘子,验证了原始平衡范数次优,且学习到的尺度能适应数据分布,显著提升性能;进一步,针对行与列的范数也受约束的问题,引入逐行、逐列的可学习乘子,使尺度自由化。该方法可视为muP乘子的可学习、更具表达力的推广。实验表明,其性能超越精心调优的muP基线,降低乘子调参开销,并揭示前向传递对称性与缩放系数的宽度依赖性等实际问题。最终在Adam与Muon优化器下均验证有效,下游评估提升幅度相当于从Adam切换至Muon的效果。

原文摘要 · Abstract (English)

Applying weight decay (WD) to matrix layers is standard practice in large-language-model pretraining. Prior work suggests that stochastic gradient noise induces a Brownian-like expansion of the weight matrices W, whose growth is counteracted by WD, leading to a WD-noise equilibrium with a certain weight norm ||W||. In this work, we view the equilibrium norm as a harmful artifact of the training procedure, and address it by introducing learnable multipliers to learn the optimal scale. First, we attach a learnable scalar multiplier to W and confirm that the WD-noise equilibrium norm is suboptimal: the learned scale adapts to data and improves performance. We then argue that individual row and column norms are similarly constrained, and free their scale by introducing learnable per-row and per-column multipliers. Our method can be viewed as a learnable, more expressive generalization of muP multipliers. It outperforms a well-tuned muP baseline, reduces the computational overhead of multiplier tuning, and surfaces practical questions such as forward-pass symmetries and the width-scaling of the learned multipliers. Finally, we validate learnable multipliers with both Adam and Muon optimizers, where it shows improvement in downstream evaluations matching the improvement of the switching from Adam to Muon.

大模型训练可学习缩放权重衰减优化器

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