Parameter-efficient fine-tuning (PEFT) adapts a pretrained model by updating only a small fraction of its parameters or adding trainable modules. It reduces compute and cost while often preserving accuracy and robustness, making domain adaptation more practical than full fine-tuning. section 2.4 section 2.3
Common PEFT approaches include:
- LoRA freezes pretrained weights and trains low-rank updates for selected weight matrices. section 2.4
- Prefix tuning and prompt tuning optimize continuous task-specific vectors or prompt embeddings while keeping the model frozen. section 2.4
- AdaLoRA reallocates its parameter budget according to importance scores, while LoftQ combines quantization with low-rank initialization. section 2.4
Figure 2.3 The LoRA fine-tuning process
Use the process diagram to see how LoRA preserves pretrained weights while training a smaller adaptation component. section 2.4
LoRA domain adaptation
A practical workflow loads FLAN-T5-small in 8-bit mode, prepares it for k-bit training, targets the q and v modules with a LoRA configuration, trains on the SAMSum dialogue-summarization dataset, saves the adapter, and reloads it for generation. section 2.4




