Open Source LLM: Llama 2
Tags: llm, opensource, ai
Published: 2023-08-08 13:51:51

In this Blog, I will give you a description about Llama 2 from Meta' s prospective and also the steps on how you can contribute to Meta's Model:

**Llama 2**
Meta has unlocked the power of large language models. Meta's latest version of Llama is now accessible to individuals, creators, researchers and businesses of all sizes so that they can experiment, innovate and scale their ideas responsibly.

This release includes model weights and starting code for pretrained and fine-tuned Llama language models — ranging from 7B to 70B parameters.

This repository is intended as a minimal example to load Llama 2 models and run inference. For more detailed examples leveraging HuggingFace, see llama-recipes.

Updates post-launch
See UPDATES.md.

Download
⚠️ 7/18: We're aware of people encountering a number of download issues today. Anyone still encountering issues should remove all local files, re-clone the repository, and request a new download link. It's critical to do all of these in case you have local corrupt files. When you receive the email, copy only the link text - it should begin with https://download.llamameta.net and not with https://l.facebook.com, which will give errors.

In order to download the model weights and tokenizer, please visit the Meta AI website and accept our License.

Once your request is approved, you will receive a signed URL over email. Then run the download.sh script, passing the URL provided when prompted to start the download. Make sure that you copy the URL text itself, do not use the 'Copy link address' option when you right click the URL. If the copied URL text starts with: https://download.llamameta.net, you copied it correctly. If the copied URL text starts with: https://l.facebook.com, you copied it the wrong way.

Pre-requisites: make sure you have wget and md5sum installed. Then to run the script: ./download.sh.

Keep in mind that the links expire after 24 hours and a certain amount of downloads. If you start seeing errors such as 403: Forbidden, you can always re-request a link.

Access on Hugging Face
We are also providing downloads on Hugging Face. You must first request a download from the Meta AI website using the same email address as your Hugging Face account. After doing so, you can request access to any of the models on Hugging Face and within 1-2 days your account will be granted access to all versions.

Setup
In a conda env with PyTorch / CUDA available, clone the repo and run in the top-level directory:

pip install -e .
Inference
Different models require different model-parallel (MP) values:

Model	MP
7B	1
13B	2
70B	8
All models support sequence length up to 4096 tokens, but we pre-allocate the cache according to max_seq_len and max_batch_size values. So set those according to your hardware.

Pretrained Models
These models are not finetuned for chat or Q&A. They should be prompted so that the expected answer is the natural continuation of the prompt.

See example_text_completion.py for some examples. To illustrate, see command below to run it with the llama-2-7b model (nproc_per_node needs to be set to the MP value):

torchrun --nproc_per_node 1 example_text_completion.py \
    --ckpt_dir llama-2-7b/ \
    --tokenizer_path tokenizer.model \
    --max_seq_len 128 --max_batch_size 4
Fine-tuned Chat Models
The fine-tuned models were trained for dialogue applications. To get the expected features and performance for them, a specific formatting defined in chat_completion needs to be followed, including the INST and 
 tags, BOS and EOS tokens, and the whitespaces and breaklines in between (we recommend calling strip() on inputs to avoid double-spaces).

You can also deploy additional classifiers for filtering out inputs and outputs that are deemed unsafe. See the llama-recipes repo for an example of how to add a safety checker to the inputs and outputs of your inference code.

Examples using llama-2-7b-chat:

torchrun --nproc_per_node 1 example_chat_completion.py \
    --ckpt_dir llama-2-7b-chat/ \
    --tokenizer_path tokenizer.model \
    --max_seq_len 512 --max_batch_size 4
Llama 2 is a new technology that carries potential risks with use. Testing conducted to date has not — and could not — cover all scenarios. In order to help developers address these risks, we have created the Responsible Use Guide. More details can be found in our research paper as well.

Issues
Please report any software “bug,” or other problems with the models through one of the following means:

Reporting issues with the model: github.com/facebookresearch/llama
Reporting risky content generated by the model: developers.facebook.com/llama_output_feedback
Reporting bugs and security concerns: facebook.com/whitehat/info
Model Card
See MODEL_CARD.md.

License
Our model and weights are licensed for both researchers and commercial entities, upholding the principles of openness. Our mission is to empower individuals, and industry through this opportunity, while fostering an environment of discovery and ethical AI advancements.

See the LICENSE file, as well as our accompanying Acceptable Use Policy

References
Research Paper
Llama 2 technical overview
Open Innovation AI Research Community
Original LLaMA
The repo for the original llama release is in the llama_v1 branch.

**Contributing to Llama**

We want to make contributing to this project as easy and transparent as possible.

Pull Requests
We actively welcome your pull requests.

Fork the repo and create your branch from main.
If you've added code that should be tested, add tests.
If you've changed APIs, update the documentation.
Ensure the test suite passes.
Make sure your code lints.
If you haven't already, complete the Contributor License Agreement ("CLA").
Contributor License Agreement ("CLA")
In order to accept your pull request, we need you to submit a CLA. You only need to do this once to work on any of Meta's open source projects.

Complete your CLA here: https://code.facebook.com/cla

Issues
We use GitHub issues to track public bugs. Please ensure your description is clear and has sufficient instructions to be able to reproduce the issue.

Meta has a bounty program for the safe disclosure of security bugs. In those cases, please go through the process outlined on that page and do not file a public issue.

License
By contributing to Llama, you agree that your contributions will be licensed under the LICENSE file in the root directory of this source tree.

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