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Dynamic Loss-Based Sample Reweighting for Improved Large Language Model Pretraining (2502.06733v1)

Published 10 Feb 2025 in cs.LG and cs.AI

Abstract: Pretraining LLMs on vast and heterogeneous datasets is crucial for achieving state-of-the-art performance across diverse downstream tasks. However, current training paradigms treat all samples equally, overlooking the importance or relevance of individual samples throughout the training process. Existing reweighting strategies, which primarily focus on group-level data importance, fail to leverage fine-grained instance-level information and do not adapt dynamically to individual sample importance as training progresses. In this paper, we introduce novel algorithms for dynamic, instance-level data reweighting aimed at improving both the efficiency and effectiveness of LLM pretraining. Our methods adjust the weight of each training sample based on its loss value in an online fashion, allowing the model to dynamically focus on more informative or important samples at the current training stage. In particular, our framework allows us to systematically devise reweighting strategies deprioritizing redundant or uninformative data, which we find tend to work best. Furthermore, we develop a new theoretical framework for analyzing the impact of loss-based reweighting on the convergence of gradient-based optimization, providing the first formal characterization of how these strategies affect convergence bounds. We empirically validate our approach across a spectrum of tasks, from pretraining 7B and 1.4B parameter LLMs to smaller-scale LLMs and linear regression problems, demonstrating that our loss-based reweighting approach can lead to faster convergence and significantly improved performance.

Summary

  • The paper proposes dynamically reweighting individual training samples based on their loss values throughout LLM pretraining to enhance efficiency and effectiveness.
  • It presents a theoretical framework showing how strategically down-weighting low-loss samples can contribute to faster convergence during gradient-based optimization.
  • Empirical experiments across various model scales demonstrate that this dynamic loss-based reweighting significantly improves convergence speeds and overall model performance.

Dynamic Loss-Based Sample Reweighting for Improved LLM Pretraining

The research paper presented focuses on enhancing the pretraining efficiency and efficacy of LLMs by introducing a method of dynamic, instance-level data reweighting predicated on the loss values of individual training samples. As the size of datasets for pretraining LLMs scales to voluminous proportions, optimizing which parts of these data receive more attention during training becomes crucial for achieving not only quicker convergence but also better model performance across diverse applications.

Traditionally, LLM pretraining involves treating every sample homogeneously within the training objective, often missing the opportunity to better leverage sample-specific importance. This paper proposes an innovative alternative by dynamically adjusting the weights of individual samples based on their loss value, which varies throughout the training process. This not only allows for a more focused learning approach on parts of the data considered more informative but also deprioritizes redundant or uninformative data, conserving computational resources.

Key Contributions and Theoretical Foundation

  1. Instance-Level Loss-Based Reweighting:
    • The authors establish a systematic approach to reweighting strategies based at the instance level, allowing for adjustment in response to each sample's changing importance during the training phases. This method draws from the tenets of penalizing or boosting the importance of a sample by actively adapting its weight relative to the model's current state.
  2. New Theoretical Framework:
    • The research introduces a theoretical framework illustrating how instance-level loss-based reweighting impacts the convergence of gradient-based optimization. A compelling finding is that strategically down-weighting low-loss samples contributes to faster convergence rates. This is analytically validated by deriving bounds within which reweighting boosts the training convergence, a novel contribution in quantifying the dynamic weight adjustments' effect.
  3. Empirical Validation:
    • Empirically, the methods are probed across various scenarios, from larger models with parameters going up to billions to linear regression tasks, validating the robustness of these loss-based adjustments in promoting efficiency and effectiveness in model training. Notably, the empirical assessment confirms that the efficiency gains are consistent, confirming the method’s practicality for different scales of problem complexity.

Results and Implications

The empirical results underline that the proposed reweighting significantly improves convergence speeds and model performance. For instance, in scenarios involving pretraining models with millions to billions of parameters, the incorporation of loss-based reweighting led to considerable improvements in performance benchmarks. Moreover, when combined with existing domain-level reweighting strategies, the proposed instance-level methods showed synergistic effects, further enhancing model robustness and flexibility across varied reasoning and other language-based tasks.

The practical implications of this work extend into reducing the dependency on extensive manual data curation and selection, considering dynamic data leveraging could optimize sample importance more holistically, potentially scaling more transparently with evolving datasets.

Conclusion and Future Perspectives

In summary, the paper proposes a strategic pivot in how instance-specific losses are traditionally perceived and utilized within the LLM pretraining paradigm. By leveraging these dynamic reweighting strategies, the research not only addresses an existing inefficiency but also extends a framework, both theoretical and empirical, that can significantly impact future developments in AI and natural language processing realms. This creates avenues for further paper, particularly in applying similar strategies across other machine learning domains and potentially extending the analytical and empirical bounds of such dynamic training methodologies. Future research might investigate incorporating continuous updating mechanisms as models evolve, considering their application to real-time language processing tasks and other dynamic AI challenges.