Adacc动态统一压缩与重计算,提升大模型训练效率。
Adacc: An Adaptive Framework Unifying Compression and Activation Recomputation for LLM Training
- 根据张量特征和硬件条件,动态选择重计算、保留或压缩。
- 相比最先进框架,训练吞吐提升1.01倍至1.37倍,精度相当。
- 支持层内自适应压缩算法与运行时策略进化,适合大模型训练优化。
大语言模型(LLM)训练常受GPU显存限制。为缓解内存压力,激活重计算和数据压缩是两种主要策略,但各有缺陷:重计算带来显著训练开销,而简单压缩会导致精度下降和计算低效。本文提出Adacc,首个统一激活重计算与数据压缩的自适应内存优化框架,可在保持模型精度的同时提升训练效率。不同于静态或单一策略方法,Adacc在张量级别进行细粒度决策,依据张量特性与运行时硬件约束,动态选择重计算、保留或压缩。其解决三大挑战:(1) 提出层特定压缩算法,通过处理激活中的异常值减轻精度损失;(2) 采用基于混合整数线性规划(MILP)的调度策略,全局优化跨层内存策略;(3) 集成自适应策略演化机制,根据数据分布变化动态更新策略。实验表明,与当前最优框架相比,Adacc在保持基线精度的前提下,训练吞吐提升1.01倍至1.37倍。
原文摘要 · Abstract (English)
Training large language models (LLMs) is often constrained by GPU memory limitations. To alleviate memory pressure, activation recomputation and data compression have been proposed as two major strategies. However, both approaches have limitations: recomputation introduces significant training overhead, while compression can lead to accuracy degradation and computational inefficiency when applied naively. In this paper, we propose Adacc, the first adaptive memory optimization framework that unifies activation recomputation and data compression to improve training efficiency for LLMs while preserving model accuracy. Unlike existing methods that apply static, rule-based strategies or rely solely on one technique, Adacc makes fine-grained, tensor-level decisions, dynamically selecting between recomputation, retention, and compression based on tensor characteristics and runtime hardware constraints. Adacc tackles three key challenges: (1) it introduces layer-specific compression algorithms that mitigate accuracy loss by accounting for outliers in LLM activations; (2) it employs a MILP-based scheduling policy to globally optimize memory strategies across layers; and (3) it integrates an adaptive policy evolution mechanism to update strategies during training in response to changing data distributions. Experimental results show that Adacc improves training throughput by 1.01x to 1.37x compared to state-of-the-art frameworks, while maintaining accuracy comparable to the baseline.
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