GraLoRA: Granular Low-Rank Adaptation for Parameter-Efficient Fine-Tuning
LoRA suffers from structural bottlenecks at high ranks, causing gradient entanglement across input channels, which leads to overfitting and performance saturation—hindering its ability to approximate full fine-tuning (FFT). To address this, we propose Granular Low-Rank Adaptation (GraLoRA), the first sub-block-level low-rank adaptation framework: it partitions the weight matrix into fine-grained blocks and assigns each block an independent low-rank adapter, explicitly decoupling gradient propagation paths. This design incurs virtually zero additional parameters or computational overhead while substantially enhancing representational capacity and FFT approximation fidelity. On HumanEval+, GraLoRA achieves a +8.5% improvement in Pass@1, consistently outperforming LoRA and other PEFT baselines across diverse model scales and rank configurations. Its performance demonstrates strong robustness and scalability.