PELA: Learning Parameter-Efficient Models with Low-Rank Approximation

Yangyang Guo, Guangzhi Wang, Mohan S. Kankanhalli

Abstract: Applying a pre-trained large model to downstream tasks is prohibitive under resource-constrained conditions. Recent dominant approaches for addressing efficiency issues involve adding a few learnable parameters to the fIxed backbone model. This strategy, however, leads to more challenges in loading large models for downstream finetuning with limited resources. In this paper, we propose a novel method for increasing the parameter efficiency of pretrained models by introducing an intermediate pre-training stage. To this end, we first employ low-rank approximation to compress the original large model and then devise a feature distillation module and a weight perturbation regularization module. These modules are specifically designed to enhance the low-rank model. In particular, we update only the low-rank model while freezing the backbone parameters during pre-training. This allows for direct and efficient utilization of the low-rank model for downstream finetuning tasks. The proposed method achieves both efficiencies in terms of required parameters and computation time while maintaining comparable results with minimal modifications to the backbone architecture. Specifically, when applied to three vision-only and one vision-language Transformer models, our approach often demonstrates a merely rvO.6 point decrease in performance while reducing the original parameter size by 1/3 to 2/3. We release our code at link.