GLA-LoRA: Parameter-efficient LLM fine-tuning with global-local knowledge alignment

The rapid advancement of large language models (LLMs) has revolutionized natural language processing, yet their enormous parameter size presents significant challenges for fine-tuning on downstream tasks. While parameter-efficient fine-tuning (PEFT) methods such as Low-Rank Adaptation (LoRA) and Quantized LoRA (QLoRA) have substantially reduced computational requirements, they often introduce knowledge misalignment and representation degradation during adaptation. To bridge this gap, we propose GLA-LoRA, a novel PEFT framework centered on Global-Local Knowledge Alignment. Our approach establishes a unified learning strategy that synergistically integrates multi-granular contrastive learning with knowledge distillation. GLA-LoRA explicitly preserves dataset-wide semantic structures through global contrastive learning and maintains sample-level feature consistency via local invariance learning, while a teacher model guides the adaptation to retain the original model's knowledge. Extensive evaluations across eight benchmarks, spanning six GLUE tasks and two intent detection datasets, demonstrate that GLA-LoRA consistently outperforms strong baselines including standard LoRA and QLoRA. Under identical parameter budgets, GLA-LoRA achieves consistent and significant improvements over standard LoRA across three base models and eight benchmark datasets. On sentence-level classification and regression tasks, our method yields average accuracy gains of 1.4%, 1.1%, and 1.2% on LLaMA2-7B, RoBERTa_base, and BERT_Large, respectively. For intent detection (CLINC and HWU), it achieves even more pronounced improvements, with up to 2.3% accuracy gain on BERT_Large. These results establish that explicit global-local knowledge alignment is essential for achieving high-fidelity, parameter-efficient fine-tuning across diverse language tasks.