chasemcdo/loraplus

LoRA+

This repository contains the code for LoRA+, introduced in LoRA+: Efficient Low Rank Adaptation of Large Models.

Usage

LoRA+ introduces one new required hyperparameter to your optimizer (and another optional hyperparameter). Setting this hyperparameter appropriately can improve finetuning performance, especially on more challenging downstream tasks.

LoRA+ arguments

• loraplus_lr_ratio: the ratio of learning rates $\eta_B / \eta_A$ where $\eta_A$ is passed in as the optimizer learning rate (e.g., learning_rate or lr). See the note below for some advice on how to set this.
• loraplus_lr_embedding: (optional) if LoRA modules are added to embedding layers your can specify a different learning rate for them. Default value 1e-6.

NOTE: loraplus_lr_ratio should be $\geq 1$, but the optimal choice of loraplus_lr_ratio is

1. model and task dependent.
2. needs to be set in tandem with the optimizer learning rate (i.e., $\eta_A$).

As a rule of thumb, loraplus_lr_ratio should be larger when the task is more difficult and the model needs to update its features to learn well. In this case, it helps to make the learning rate $\eta_A$ slightly smaller (e.g., by a factor of 2) than typical vanilla LoRA learning rates. Please see the paper for examples.

Code

The code for using LoRA+ can be found in lora_plus.py.

With Huggingface Trainer

To integrate LoRA+ into a finetuning project using huggingface Trainer is straightforward. Just replace the Trainer in your project with LoraPlusTrainer and pass in the training arguments (including LoRA+ arguments) using LoraPlusTrainingArguments. See the image_classification.ipynb notebook for an example.

No Trainer

For training with LoRA+ without Trainer you can just use an optimizer created with the create_loraplus_optimizer function. This function wraps an optimizer class and sets the learning rates of your model parameters appropriately for the optimizer.

import torch

# LoRA model
model = ...

optimizer_cls = torch.optim.AdamW
optimizer_kwargs = {'lr': 5e-5, 'eps': 1e-6, 'betas': (0.9, 0.999), 'weight_decay': 0.0}
loraplus_lr_ratio = 20.0
optimizer = create_loraplus_optimizer(model, optimizer_cls, optimizer_kwargs, loraplus_ratio):

Examples

In the glue/ folder we have code for finetuning models on GLUE using LoRA+ which can be used to reproduce results in the paper. We also include a notebook image_classification.ipynb for demonstrating code usage.

Requirements

To run the code, first install the requirements using:

pip install -r requirements.txt

Running GLUE Experiments

Download the glue tasks using e.g. :

python download_glue.py --task_names mnli,qqp --datadir data/

Check scripts/ folder for finetuning examples with gpt2, roberta-base, and llama-7b.

Citation

This code is part of the LoRA+ project. For citations, please use

@article{hayou2024loraplus,
      title={LoRA+: Efficient Low Rank Adaptation of Large Models}, 
      author={Soufiane Hayou and Nikhil Ghosh and Bin Yu},
      year={2024},
      journal={arXiv 2402.12354}
}

Acknowledgements

We thank Amazon Web Services (AWS) for providing the compute for this project through cloud credits under an Amazon Research Award.