自回归生成建模的缩放定律

Scaling Laws for Autoregressive Generative Modeling

贾里德·卡普兰 Jared Kaplan · OpenAI · 2020-10-28 · arXiv:2010.14701 ↗ · 被引 632

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摘要 · Abstract

我们确定了四个领域(生成图像建模、视频建模、多模态图像-文本模型和数学问题求解)中交叉熵损失的经验缩放定律。在所有情况下,自回归 Transformer 的性能随着模型大小和计算预算的增加而平滑提升,遵循幂律加常数的缩放定律。最优模型大小也通过幂律依赖于计算预算,其指数在所有数据域中几乎通用。交叉熵损失具有信息论解释:S(真实) + D_KL(真实||模型),经验缩放定律预测了真实数据分布的熵以及真实分布与模型分布之间的 KL 散度。根据这一解释,数十亿参数的 Transformer 几乎是 YFCC100M 图像分布下采样到 8×8 分辨率的完美模型,我们可以预测达到任何给定可减少损失(即 D_KL,单位为 nats/图像)所需的其他分辨率的模型大小。我们在特定领域发现了额外的缩放定律:(a)我们确定了多模态模型中标题与图像之间互信息的缩放关系,并回答了“一图胜千言?”的问题;(b)在数学问题求解中,我们确定了模型在训练分布外推时的性能缩放定律;(c)我们对生成图像模型进行微调用于 ImageNet 分类,发现即使生成损失趋于平稳,分类损失和错误率仍平滑缩放。综合来看,这些结果强化了缩放定律对神经网络性能(包括下游任务)具有重要意义的观点。

We identify empirical scaling laws for the cross-entropy loss in four domains: generative image modeling, video modeling, multimodal image$\leftrightarrow$text models, and mathematical problem solving. In all cases autoregressive Transformers smoothly improve in performance as model size and compute budgets increase, following a power-law plus constant scaling law. The optimal model size also depends on the compute budget through a power-law, with exponents that are nearly universal across all data domains. The cross-entropy loss has an information theoretic interpretation as $S($True$) + D_{\mathrm{KL}}($True$||$Model$)$, and the empirical scaling laws suggest a prediction for both the true data distribution's entropy and the KL divergence between the true and model distributions. With this interpretation, billion-parameter Transformers are nearly perfect models of the YFCC100M image distribution downsampled to an $8\times 8$ resolution, and we can forecast the model size needed to achieve any given reducible loss (ie $D_{\mathrm{KL}}$) in nats/image for other resolutions. We find a number of additional scaling laws in specific domains: (a) we identify a scaling relation for the mutual information between captions and images in multimodal models, and show how to answer the question "Is a picture worth a thousand words?"; (b) in the case of mathematical problem solving, we identify scaling laws for model performance when extrapolating beyond the training distribution; (c) we finetune generative image models for ImageNet classification and find smooth scaling of the classification loss and error rate, even as the generative loss levels off. Taken together, these results strengthen the case that scaling laws have important implications for neural network performance, including on downstream tasks.

核心贡献 · Key contributions

局限 · Limitations

论文章节 · Sections(共 30)

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