It is a common practice in natural language processing to pre-train a single model on a general domain and then fine-tune it for downstream tasks. However, when it comes to Large Language Models, fine-tuning the entire model can be computationally expensive, resulting in very intensive energy consumption. As a result, several Parameter efficient fine-tuning (PEFT) approaches were recently proposed. One of the most popular approaches is low-rank adaptation (LoRA), where the key insight is decomposing the update weights of the pre-trained model into two low-rank matrices. However, the proposed approaches either use the same rank value across all different weight matrices or do not use any quantization technique, which has been shown to be one of the most important factors when it comes to a model's energy consumption. In this work, we propose Bayesian-LoRA (B-LoRA) which approaches matrix decomposition and quantization from a Bayesian perspective by employing a prior distribution on both quantization levels and rank values of the learned low-rank matrices. As a result, B-LoRA is able to fine-tune a pre-trained model on a specific downstream task, finding the optimal rank values and quantization levels for every low-rank matrix. We validate the proposed model fine-tuning a pre-trained DeBERTaV3 on the GLUE benchmark. Moreover, we compare it to relevant baselines and present both qualitative and quantitative results, showing how the proposed approach is able to learn optimal-rank quantized matrices. B-LoRA performs on par or better than baselines while reducing the total amount of bit operations of roughly 70% with respect to the baselines ones.

在这项研究中，我们提出了一种基于贝叶斯角度的矩阵分解和量化方法，名为B-LoRA，通过对学习到的低秩矩阵的量化级别和秩值引入先验分布，使其能够在特定任务上对预训练模型进行精细调节，找到每个低秩矩阵的最佳秩值和量化级别。通过在GLUE基准上对预训练的DeBERTaV3模型进行验证，并将其与相关基准进行比较，我们展示了该方法如何学习到最优秩的量化矩阵，相比基线方法，B-LoRA在性能上与基线相当或更好，并且减少了大约70%的总比特操作量。

贝叶斯-LoRA：使用最佳量化水平和等级值通过可微分贝叶斯门进行参数高效微调的基于LoRA的方法