提出两种新方法,在节省25%内存的同时,让小模型预训练效果超越主流高效算法。
Scalable Parameter and Memory Efficient Pretraining for LLM: Recent Algorithmic Advances and Benchmarking
- 通过权重重构和动量重置,提升低秩方法在预训练中的表现。
- 在10亿参数模型上,新方法比GaLore、Fira等更低困惑度。
- 揭示高秩更新是提升低秩方法性能的关键,适合资源受限的预训练场景。
得益于强大的多领域任务处理能力,大语言模型(LLMs)以空前速度增长,部分模型参数达万亿级别。这一增长带来巨大的计算挑战,尤其是在训练和微调所需的内存与算力方面。尽管诸如LoRA等方法在微调中有效,但其在预训练中的应用仍面临巨大挑战,因需处理海量数据。本文旨在回答:参数或内存高效方法能否在保持与全模型相当性能的前提下提升预训练效率?如何缩小性能差距?为此,工作贡献包括:(1) 系统综述当前高效的预训练方法;(2) 对多个代表性内存高效预训练方法进行基准评估,发现适当选择优化器与超参数下,全秩训练表现最佳;同时发现,将高秩更新引入低秩方法是提升性能的关键;(3) 提出两种实用技术——权重重构与动量重置,应用于10亿参数模型时,可在约25%更少内存下实现低于GaLore和Fira的困惑度。
原文摘要 · Abstract (English)
Fueled by their remarkable ability to tackle diverse tasks across multiple domains, large language models (LLMs) have grown at an unprecedented rate, with some recent models containing trillions of parameters. This growth is accompanied by substantial computational challenges, particularly regarding the memory and compute resources required for training and fine-tuning. Numerous approaches have been explored to address these issues, such as LoRA. While these methods are effective for fine-tuning, their application to pre-training is significantly more challenging due to the need to learn vast datasets. Motivated by this issue, we aim to address the following questions: Can parameter- or memory-efficient methods enhance pre-training efficiency while achieving performance comparable to full-model training? How can the performance gap be narrowed? To this end, the contributions of this work are the following. (1) We begin by conducting a comprehensive survey that summarizes state-of-the-art methods for efficient pre-training. (2) We perform a benchmark evaluation of several representative memory efficient pre-training approaches to comprehensively evaluate their performance across model sizes. We observe that with a proper choice of optimizer and hyperparameters, full-rank training delivers the best performance, as expected. We also notice that incorporating high-rank updates in low-rank approaches is the key to improving their performance. (3) Finally, we propose two practical techniques, namely weight refactorization and momentum reset, to enhance the performance of efficient pre-training methods. We observe that applying these techniques to the low-rank method (on a 1B model) can achieve a lower perplexity than popular memory efficient algorithms such as GaLore and Fira, while simultaneously using about 25% less memory.
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