LLaMA是由Meta开源的一个大语言模型，是最近几个月一系列开源模型的基础模型。包括著名的vicuna系列、LongChat系列等都是基于该模型微调得到。可以说，LLaMA的开源促进了大模型在开源界繁荣发展。而刚刚，微软官方宣布Azure上架LLaMA2模型！这意味着LLaMA2正式发布！
LLaMA2比LLaMA1多40%的训练数据，性能更加强大，但是依然完全免费可商用！
根据官方的介绍，Meta和Microsoft准备将LLaMA2引入到Azure公有云以及Windows本地上。目前已经在AzureAI上开放了LLaMA2系列的6个模型供大家使用。
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LLaMA2模型的参数范围从70亿到700亿不等，在超过2万亿tokens数据集上训练。官方对齐微调的结果称为LLaMA2-Chat系列，专门针对场景优化。
LLaMA2-Chat模型在微软测试的大多数基准测试中胜过开源聊天模型，并在人工评估中在实用性和安全性方面与一些流行的闭源模型如ChatGPT和PaLM相当。
LLaMA2具体的模型信息如下：
| |参数|上下文长度|GQA|训练tokens|学习率| |:----|:----|:----|:----|:----|:----|:----| |LLaMA2-7B|7B|4k|✗|2万亿|3.0 x 10-4| |LLaMA2-13B|13B|4k|✗|2万亿|3.0 x 10-4| |LLaMA2-700B|70B|4k|✔|2万亿|1.5 x 10-4|
所有模型都使用全局批量大小为4M tokens进行训练。更大的700亿参数模型使用Grouped-Query Attention（GQA）来提高推理可扩展性。
LLaMA2的训练时间为2023年1月至2023年7月。且是一个纯文本模型，仅接受文本输入和文本的输出。
预训练过程中，Meta估计使用了总计33万GPU小时的计算，硬件类型为A100-80GB（功耗为350-400W）。
LLaMA2是一种优化的自回归语言变换器。微调版本使用监督微调（SFT）和人工反馈强化学习（RLHF）来对齐人类对实用性和安全性的偏好。
LLaMA2是在来自公开可用来源的2万亿tokens数据上进行的预训练。微调数据包括公开可用的指令数据集，以及超过100万个新的人工注释示例。预训练和微调数据集均不包含Meta用户数据。
预训练数据的截止日期为2022年9月，但某些微调数据更近，最新的可达到2023年7月。
官方给出了详细信息：
可以看到，LLaMA2在各方面都超过第一代很多。尤其是数学、文本理解等方面。代码方面的得分也不错。
官方表示LLaMA2完全开源可商用，都没写啥具体协议：
不过，使用依然需要填写表单申请，需要审核通过后才可以下载。
官方给出了实际测试结果： 输入：
{
"input_data": {
"input_string": [
{
"role": "user",
"content": "I am going to Paris, what should I see?"
},
{
"role": "assistant",
"content": "Paris, the capital of France, is known for its stunning architecture, art museums, historical landmarks, and romantic atmosphere. Here are some of the top attractions to see in Paris:\n\n1. The Eiffel Tower: The iconic Eiffel Tower is one of the most recognizable landmarks in the world and offers breathtaking views of the city.\n2. The Louvre Museum: The Louvre is one of the world's largest and most famous museums, housing an impressive collection of art and artifacts, including the Mona Lisa.\n3. Notre-Dame Cathedral: This beautiful cathedral is one of the most famous landmarks in Paris and is known for its Gothic architecture and stunning stained glass windows.\n\nThese are just a few of the many attractions that Paris has to offer. With so much to see and do, it's no wonder that Paris is one of the most popular tourist destinations in the world."
},
{
"role": "user",
"content": "What is so great about #1?"
}
],
"parameters": {
"max_length": 200,
"temperature": 0.6,
"top_p": 0.9,
"do_sample": true,
"max_new_tokens": 200
}
}
}
输出结果：
{
"output": "There are many reasons why the Eiffel Tower is one of the most iconic landmarks in Paris and a must-see attraction for visitors. Here are a few of the reasons why it's so great:\n\n1. Unique Design: The Eiffel Tower is an engineering marvel, with its unique design and shape that sets it apart from other landmarks around the world.\n2. Scale: The Eiffel Tower is an enormous structure, standing at over 1,000 feet tall, and offers breathtaking views of the city from its top platform.\n3. History: The Eiffel Tower was built for the World's Fair in 1889 and has since become a symbol of Paris and French culture.\n4. Romantic Atmosphere: The Eiffel Tower is often called the most romantic spot in Paris, and is a popular spot for couples to visit and take in"
}
目前LLaMA2模型首先上架了Azure的模型服务。包括如下几个：
关键微软发布的信息，LLaMA2支持聊天应用也支持微调部署~未来也会在Windows本地引入该模型。只是，微软与Meta走得这么近，OpenAI咋办呢~~
LLaMA2的开源地址：https://github.com/facebookresearch/llama/blob/main/MODEL_CARD.md LLaMA2的下载地址：https://ai.meta.com/resources/models-and-libraries/llama-downloads/ LLaMA2的官方博客地址：https://ai.meta.com/resources/models-and-libraries/llama/