Fine-Tune Your First LLM¶
This guide will walk you through the process of launching your first finetuning job using torchtune.
How to download a model from the Hugging Face Hub
How to modify a recipe’s parameters to suit your needs
How to run a finetune
Be familiar with the overview of torchtune
Make sure to install torchtune
Downloading a model¶
The first step in any finetuning job is to download a pretrained base model. torchtune supports an integration with the Hugging Face Hub - a collection of the latest and greatest model weights.
For this tutorial, you’re going to use the Llama2 7B model from Meta. Llama2 is a “gated model”, meaning that you need to be granted access in order to download the weights. Follow these instructions on the official Meta page hosted on Hugging Face to complete this process. This should take less than 5 minutes. To verify that you have the access, go to the model page. You should be able to see the model files. If not, you may need to accept the agreement to complete the process.
Note
Alternatively, you can opt to download the model directly through the Llama2 repository. See this page for more details.
Once you have authorization, you will need to authenticate with Hugging Face Hub. The easiest way to do so is to provide an access token to the download script. You can find your token here.
Then, it’s as simple as:
tune download meta-llama/Llama-2-7b-hf \
--output-dir /tmp/Llama-2-7b-hf \
--hf-token <ACCESS TOKEN>
This command will also download the model tokenizer and some other helpful files such as a Responsible Use guide.
Selecting a recipe¶
Recipes are the primary entry points for torchtune users. These can be thought of as hackable, singularly-focused scripts for interacting with LLMs including training, inference, evaluation, and quantization.
Each recipe consists of three components:
Configurable parameters, specified through yaml configs and command-line overrides
Recipe script, entry-point which puts everything together including parsing and validating configs, setting up the environment, and correctly using the recipe class
Recipe class, core logic needed for training, exposed through a set of APIs
Note
To learn more about the concept of “recipes”, check out our technical deep-dive: What Are Recipes?.
torchtune provides built-in recipes for finetuning on single device, on multiple devices with FSDP,
using memory efficient techniques like LoRA, and more! Check out all our built-in recipes in our recipes overview. You can also utilize the
tune ls command to print out all recipes and corresponding configs.
$ tune ls
RECIPE CONFIG
full_finetune_single_device llama2/7B_full_low_memory
mistral/7B_full_low_memory
full_finetune_distributed llama2/7B_full
llama2/13B_full
mistral/7B_full
lora_finetune_single_device llama2/7B_lora_single_device
llama2/7B_qlora_single_device
mistral/7B_lora_single_device
...
For the purposes of this tutorial, you’ll will be using the recipe for finetuning a Llama2 model using LoRA on a single device. For a more in-depth discussion on LoRA in torchtune, you can see the complete “Fine-Tuning Llama2 with LoRA” tutorial.
Note
Why have a separate recipe for single device vs. distributed? This is discussed in “What Are Recipes?” but one of our core principles in torchtune is minimal abstraction and boilerplate code. If you only want to train on a single GPU, our single-device recipe ensures you don’t have to worry about additional features like FSDP that are only required for distributed training.
Modifying a config¶
YAML configs hold most of the important information needed for running your recipe. You can set hyperparameters, specify metric loggers like WandB, select a new dataset, and more. For a list of all currently supported datasets, see torchtune.datasets.
There are two ways to modify an existing config:
Override existing parameters from the command line
You can override existing parameters from the command line using a key=value format. Let’s say
you want to set the number of training epochs to 1.
tune run <RECIPE> --config <CONFIG> epochs=1
Copy the config through `tune cp` and modify directly
If you want to make more substantial changes to the config, you can use the tune CLI to copy it to your local directory.
$ tune cp llama2/7B_lora_single_device custom_config.yaml
Copied file to custom_config.yaml
Now you can update the custom YAML config any way you like. Try setting the random seed in order to make replication easier, changing the LoRA rank, update batch size, etc.
Note
Check out “All About Configs” for a deeper dive on configs in torchtune.
Training a model¶
Now that you have a model in the proper format and a config that suits your needs, let’s get training!
Just like all the other steps, you will be using the tune CLI tool to launch your finetuning run.
$ tune run lora_finetune_single_device --config llama2/7B_lora_single_device epochs=1
INFO:torchtune.utils.logging:Running LoRAFinetuneRecipeSingleDevice with resolved config:
Writing logs to /tmp/lora_finetune_output/log_1713194212.txt
INFO:torchtune.utils.logging:Model is initialized with precision torch.bfloat16.
INFO:torchtune.utils.logging:Tokenizer is initialized from file.
INFO:torchtune.utils.logging:Optimizer and loss are initialized.
INFO:torchtune.utils.logging:Loss is initialized.
INFO:torchtune.utils.logging:Dataset and Sampler are initialized.
INFO:torchtune.utils.logging:Learning rate scheduler is initialized.
1|52|Loss: 2.3697006702423096: 0%|▏ | 52/25880 [00:24<3:55:01, 1.83it/s]
You can see that all the modules were successfully initialized and the model has started training. You can monitor the loss and progress through the tqdm bar but torchtune will also log some more metrics, such as GPU memory usage, at an interval defined in the config.
Next steps¶
Now that you have trained your model and set up your environment, let’s take a look at what we can do with our new model by checking out the “E2E Workflow Tutorial”.
