minLoRA

A minimal, but versatile PyTorch re-implementation of LoRA. In only ~100 lines of code, minLoRA supports the following features:

Features

• Functional, no need to modify the model definition
• Works everywhere, as long as you use torch.nn.Module
• PyTorch native, uses PyTorch's torch.nn.utils.parametrize to do all the heavy lifting
• Easily extendable, you can add your own LoRA parameterization
• Supports training, inference, and inference with multiple LoRA models

Demo

• demo.ipynb shows the basic usage of the library
• advanced_usage.ipynb shows how you can add LoRA to other layers such as embedding, and how to tie weights

Examples

• Finetuning GPT using LoRA + nanoGPT: https://github.com/cccntu/LoRAnanoGPT/pull/1/files

Library Installation

If you want to import minlora into your project:

git clone https://github.com/cccntu/minLoRA.git
cd minLoRA
pip install -e .

Usage

import torch
from minlora import add_lora, apply_to_lora, disable_lora, enable_lora, get_lora_params, merge_lora, name_is_lora, remove_lora, load_multiple_lora, select_lora

Training a model with minLoRA

model = torch.nn.Linear(in_features=5, out_features=3)
# Step 1: Add LoRA to the model
add_lora(model)

# Step 2: Collect the parameters, pass them to the optimizer

parameters = [
    {"params": list(get_lora_params(model))},
]
optimizer = torch.optim.AdamW(parameters, lr=1e-3)

# Step 3: Train the model
# ...

# Step 4: export the LoRA parameters
lora_state_dict = get_lora_state_dict(model)

Loading and Inferencing with minLoRA

# Step 1: Add LoRA to your model
add_lora(model)

# Step 2: Load the LoRA parameters
_ = model.load_state_dict(lora_state_dict, strict=False)

# Step 3: Merge the LoRA parameters into the model
merge_lora(model)

Inferencing with multiple LoRA models

# to avoid re-adding lora to the model when rerun the cell, remove lora first
remove_lora(model)
# Step 1: Add LoRA to your model
add_lora(model)

# Step 2: Load the LoRA parameters

# load three sets of LoRA parameters
lora_state_dicts = [lora_state_dict_0, lora_state_dict_1, lora_state_dict_2]

load_multiple_lora(model, lora_state_dicts)


# Step 3: Select which LoRA to use at inference time
Y0 = select_lora(model, 0)(x)
Y1 = select_lora(model, 1)(x)
Y2 = select_lora(model, 2)(x)

References

• microsoft/LoRA has the official implementation of LoRA, in PyTorch
• karpathy/minGPT the structure of the repo is adapted from minGPT

TODO

• A notebook to show how to configure LoRA parameters
• Real training & inference examples