用预训练模型的权重谱特征初始化语言模型,效果不如直接复用原始权重。
Complexity-Guided Component-wise Initialization for Language Model Pretraining
- 基于预训练模型的组件级权重谱特征设计初始化方案。
- 虽改变模型初始结构,但未带来性能提升。
- 仅匹配谱形状不够,需保留更丰富信息才能有效复用。
预训练语言模型常表现出结构化的权重谱特征,表明训练过程会重复生成相似的层间与组件级组织模式。我们探究这些反复出现的谱模式能否作为GPT-2类语言模型预训练的初始化信号。首先分析了11个不同规模、语言、分词器和训练语料的GPT-2类检查点,测量各层及Transformer子组件的Frobenius范数与有效秩熵。结果发现各检查点具有共享的深度趋势,尤其在残差写入矩阵中表现出更强的尺度增长与谱集中性。随后构建模仿预训练模型组件级幅度与谱特征的初始化方法,并与多种权重初始化方式对比。结果显示,这些初始化器显著改变了模型的初始谱结构,但评估未体现性能优势。预训练权重复用仍具竞争力,而仅靠粗略的谱匹配无法成为可靠优化策略。结果表明,预训练谱特征对模型结构具有诊断价值,但有效复用需保留比组件级尺度和奇异值形状更丰富的信息。
原文摘要 · Abstract (English)
Pretrained language models often exhibit structured weight spectra, suggesting that training may repeatedly produce similar layerwise and component-wise organization. We ask whether these recurring spectral patterns can be reused as an initialization signal for GPT-2-style language-model pretraining. First, we analyze eleven pretrained GPT-2-style checkpoints that vary in size, language, tokenizer, and training corpus, measuring Frobenius norm and effective-rank entropy across layers and Transformer subcomponents. The checkpoints show shared depth trends, especially increasing scale and stronger spectral concentration in residual-writing matrices. We then construct initialization schemes that imitate the component-wise magnitudes and spectral profiles of pretrained models, and compare them with several weight initialization methods. These initializers visibly change the model's structural spectral patterns, but the evaluation results do not show a corresponding performance advantage. Pretrained-weight reuse remains competitive, while coarse spectral matching alone is not a reliable optimization strategy. Our results suggest that pretrained spectra are useful diagnostics of trained model structure, but that effective reuse likely requires preserving richer information than component-wise scale and singular-value shape.
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。