用可检索的梯度实现持续训练,避免参数漂移。
Retrievable Gradients: Continual Post-Training Without Cumulative Weight Drift

- 将梯度存为可检索的知识单元,按需调用临时更新模型。
- 在通用与领域任务上优于对比方法,保持性能不下降。
- 适合需要持续学习且避免遗忘的部署场景。
持续后训练使模型在部署后持续吸收新知识,但反复更新共享参数会导致权重漂移,引发灾难性遗忘并降低泛化能力。检索增强生成虽能避免参数漂移,但缺乏参数化知识整合的深度。本文提出 ReGrad(可检索梯度),将梯度视为可检索的知识单位:离线预计算文档特定梯度,存入索引梯度库,在推理时仅检索相关梯度进行临时权重调整。然而,原始语言模型梯度针对的是词元级文档重建,而非查询驱动的知识利用。为此,我们引入双层元学习目标,将文档衍生梯度重塑为适用于下游任务的可迁移适应信号。跨通用与领域设置的实验表明,ReGrad 在性能上超越 CPT 与 RAG 基线,实现可扩展、可逆的参数化知识注入,且无累积权重漂移。
原文摘要 · Abstract (English)
Continual post-training enables models to absorb emerging knowledge after deployment, but repeatedly updating shared parameters can accumulate weight drift, potentially causing catastrophic forgetting and degrading general capabilities. Retrieval-augmented generation avoids such parameter drift, yet often lacks the depth of parametric knowledge integration. In this paper, we propose ReGrad (Retrievable Gradients), a new paradigm that treats gradients as retrievable units of knowledge. ReGrad pre-computes document-specific gradients offline, stores them in an indexed Gradient Bank, and retrieves only query-relevant gradients at inference time for temporary weight adaptation. However, raw language-modeling gradients are optimized for token-level document reconstruction rather than for query-driven knowledge use. We therefore introduce a bi-level meta-learning objective that reshapes document-derived gradients into generalizable adaptation signals for downstream tasks. Experiments across general and domain-specific settings show that \textsc{ReGrad} outperforms CPT and RAG baselines, enabling scalable and reversible parametric knowledge injection without accumulating weight drift.
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