LoRA achieves remarkable resource efficiency and comparable performance when adapting LLMs for specific tasks. Since ChatGPT demonstrated superior performance on various tasks, there has been a growing desire to adapt one model for all tasks. However, the explicit low-rank of LoRA limits the adaptation performance in complex multi-task scenarios. LoRA is dominated by a small number of top singular vectors while fine-tuning decomposes into a set of less important unitary transforms. In this paper, we propose MultiLoRA for better multi-task adaptation by reducing the dominance of top singular vectors observed in LoRA. MultiLoRA scales LoRA modules horizontally and change parameter initialization of adaptation matrices to reduce parameter dependency, thus yields more balanced unitary subspaces. We unprecedentedly construct specialized training data by mixing datasets of instruction follow, natural language understanding, world knowledge, to cover semantically and syntactically different samples. With only 2.5% of additional parameters, MultiLoRA outperforms single LoRA counterparts and fine-tuning on multiple benchmarks and model scales. Further investigation into weight update matrices of MultiLoRA exhibits reduced dependency on top singular vectors and more democratic unitary transform contributions.

提出了MultiLoRA，通过减少LoRA中观察到的顶层奇异向量的主导性，通过水平扩展LoRA模块和改变适应矩阵的参数初始化来减少参数依赖性，从而产生更平衡的单元子空间，从而实现更好的多任务适应性。MultiLoRA在多个基准和模型规模上优于单个LoRA对应项和微调，仅需额外2.5％的参数。对MultiLoRA的权重更新矩阵进行进一步研究表明，其对顶层奇异向量的依赖性减小，单元变换贡献更加均衡。

MultiLoRA: 提升多任务学习效果的LoRA民主化