SmallToLarge (S2L): Scalable Data Selection for Fine-tuning Large Language Models by Summarizing Training Trajectories of Small Models
Yu Yang, Siddhartha Mishra, Jeffrey N Chiang, Baharan Mirzasoleiman
TL;DR
S2L introduces a scalable data-selection method for supervised fine-tuning in specialized-domain LLMs by leveraging loss trajectories from a small proxy model. It clusters these trajectories and uniformly samples from clusters to form a representative subset, with theoretical guarantees on gradient similarity and convergence. Empirically, S2L achieves substantial data-efficiency gains across mathematical reasoning and clinical text summarization, even transferring subsets to larger target models and reducing data and compute costs. The approach is robust to hyperparameters and proxy choice, though its evaluation is limited to two domains and assumes fixed training schedules, suggesting avenues for broader validation and optimization.
Abstract
Despite the effectiveness of data selection for large language models (LLMs) during pretraining and instruction fine-tuning phases, improving data efficiency in supervised fine-tuning (SFT) for specialized domains poses significant challenges due to the complexity of fine-tuning data. To bridge this gap, we introduce an effective and scalable data selection method for SFT, SmallToLarge (S2L), which leverages training trajectories from small models to guide the data selection for larger models. We demonstrate through extensive experiments that S2L significantly improves data efficiency in SFT for mathematical problem-solving, reducing the training data to just 11% of the original MathInstruct dataset (Yue et al., 2023) to match full dataset performance while outperforming state-of-the-art data selection algorithms by an average of 4.7% across 6 in- and out-domain evaluation datasets. Remarkably, selecting only 50K data for SFT, S2L achieves a 32.7% accuracy on the most challenging MATH (Hendrycks et al., 2021) benchmark, improving Phi-2 (Li et al., 2023b) by 16.6%. In clinical text summarization on the MIMIC-III dataset (Johnson et al., 2016), S2L again outperforms training on the full dataset using only 50% of the data. Notably, S2L can perform data selection using a reference model 40x smaller than the target model, proportionally reducing the cost of data selection.
