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Mitigating Catastrophic Forgetting in Large Language Models through Selective Fine-Tuning


Основні поняття
Half Fine-Tuning (HFT) allows large language models to acquire new abilities while retaining previously learned knowledge by selectively updating only half of the model parameters during fine-tuning.
Анотація

The paper introduces Half Fine-Tuning (HFT), a simple yet effective approach to mitigate catastrophic forgetting in large language models (LLMs) during fine-tuning.

The key insights are:

  • Resetting half of the fine-tuned parameters to the pre-trained state can help restore some of the original knowledge while maintaining new learning abilities.
  • HFT involves freezing half of the model parameters and only updating the other half during fine-tuning, without changing the model architecture.
  • HFT can be seamlessly integrated into existing fine-tuning frameworks, including supervised fine-tuning, direct preference optimization, and continual learning.

Extensive experiments demonstrate the effectiveness of HFT:

  • HFT significantly alleviates catastrophic forgetting compared to full fine-tuning (FFT), while achieving comparable or even better performance on downstream tasks.
  • HFT is robust to the selection of trainable parameters, with around 50% of parameters being updated yielding the best results.
  • HFT also improves training efficiency, reducing training time by approximately 30% compared to FFT.

The paper provides a theoretical interpretation of HFT from an optimization perspective, showing that it can be viewed as a form of regularization. The parameter variation analysis further reveals that HFT leads to more gradual changes in the model parameters compared to FFT.

Overall, HFT offers a simple yet powerful solution to preserve the knowledge of pre-trained LLMs while enabling effective fine-tuning for various tasks, making it a promising alternative to the standard fine-tuning approach.

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Статистика
Updating half of the parameters in LLAMA 2-CHAT-7B model can roughly restore a significant amount of forgotten basic knowledge while maintaining high-level general abilities performance. Compared to full fine-tuning, HFT achieves an average performance improvement of 1.9% on LLAMA 2-7B and 2.9% on LLAMA 2-13B for general abilities benchmarks. HFT consistently outperforms full fine-tuning and direct preference optimization in preserving basic knowledge, with improvements of 3.4% and 2.9% on LLAMA 2-7B and LLAMA 2-13B respectively. HFT can shorten the training time by approximately 30% compared to full fine-tuning.
Цитати
"By regularly resetting partial parameters, LLMs can restore some of the original knowledge." "Without changing the model architecture, HFT could be seamlessly integrated into existing fine-tuning frameworks." "Extensive experiments and analysis demonstrate the effectiveness and efficiency of HFT."

Ключові висновки, отримані з

by Tingfeng Hui... о arxiv.org 04-30-2024

https://arxiv.org/pdf/2404.18466.pdf
HFT: Half Fine-Tuning for Large Language Models

Глибші Запити

How can HFT be extended to handle more complex fine-tuning scenarios, such as multi-task learning or few-shot learning?

Half Fine-Tuning (HFT) can be extended to handle more complex fine-tuning scenarios by adapting its parameter selection strategy and training process. In the case of multi-task learning, where a model needs to perform well on multiple tasks, HFT can be modified to selectively freeze and update parameters based on the specific requirements of each task. For example, different subsets of parameters can be frozen or updated for different tasks, allowing the model to retain knowledge relevant to each task while learning new information. This approach ensures that the model maintains a balance between task-specific knowledge and general capabilities. In the context of few-shot learning, where a model needs to quickly adapt to new tasks with limited training data, HFT can be enhanced by incorporating meta-learning techniques. By leveraging meta-learning algorithms, HFT can learn how to effectively select and update parameters in a few-shot setting, enabling the model to efficiently adapt to new tasks with minimal data. Additionally, techniques such as dynamic parameter freezing based on task similarity or complexity can further improve the performance of HFT in few-shot learning scenarios. Overall, by customizing the parameter selection process and incorporating meta-learning strategies, HFT can be extended to handle more complex fine-tuning scenarios like multi-task learning and few-shot learning effectively.

What are the potential drawbacks or limitations of HFT, and how can they be addressed?

While Half Fine-Tuning (HFT) offers several advantages in mitigating catastrophic forgetting and improving performance in downstream tasks, there are potential drawbacks and limitations that need to be considered: Selection Bias: The random selection of parameters in HFT may introduce selection bias, leading to suboptimal performance in certain scenarios. To address this, techniques such as adaptive parameter selection based on task characteristics or model performance can be implemented to reduce bias and improve the effectiveness of HFT. Optimization Challenges: HFT may face optimization challenges when fine-tuning a large number of parameters, especially in complex models. To overcome this limitation, advanced optimization algorithms or regularization techniques can be applied to enhance the training process and ensure stable convergence. Scalability: Scaling HFT to larger models or more diverse tasks may pose scalability challenges, as the parameter selection process becomes more complex. Addressing this limitation involves optimizing the selection strategy, leveraging distributed training methods, and exploring parallel processing techniques to handle the increased computational requirements efficiently. Generalization: HFT's effectiveness may vary across different tasks and datasets, impacting its generalization capabilities. To improve generalization, incorporating transfer learning principles, exploring domain-specific fine-tuning strategies, and conducting thorough hyperparameter tuning can enhance the robustness of HFT across diverse scenarios. By addressing these drawbacks through advanced techniques, optimization strategies, and model enhancements, the limitations of HFT can be mitigated, leading to more effective and versatile fine-tuning approaches.

How might the insights from HFT inspire the development of new parameter-efficient fine-tuning techniques for large language models?

The insights from Half Fine-Tuning (HFT) can inspire the development of new parameter-efficient fine-tuning techniques for large language models in the following ways: Selective Parameter Updating: HFT's approach of selectively updating parameters while freezing others can serve as a foundation for designing more efficient fine-tuning methods. By identifying and prioritizing critical parameters for each task, new techniques can optimize the fine-tuning process and reduce computational overhead. Regularization Strategies: The regularization effect observed in HFT, where freezing parameters helps retain previous knowledge, can inspire the integration of regularization techniques in fine-tuning algorithms. By incorporating regularization methods that preserve essential information while learning new tasks, parameter-efficient fine-tuning can be achieved without sacrificing performance. Adaptive Learning Mechanisms: Insights from HFT can drive the development of adaptive learning mechanisms that dynamically adjust parameter updates based on task complexity, data availability, and model performance. By incorporating adaptive strategies into fine-tuning processes, models can efficiently adapt to changing tasks and datasets while maintaining parameter efficiency. Meta-Learning Integration: Leveraging meta-learning principles in fine-tuning techniques, inspired by HFT's approach to balancing old and new knowledge, can enhance the model's ability to quickly adapt to new tasks and domains. By incorporating meta-learning components, parameter-efficient fine-tuning methods can improve task generalization and adaptation capabilities. By leveraging the insights and principles derived from HFT, researchers can innovate and develop novel parameter-efficient fine-tuning techniques that optimize model performance, reduce computational costs, and enhance the adaptability of large language models in various applications and scenarios.
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