Several post-training quantization methods have been applied to large language models (LLMs), and have been shown to perform well down to 8-bits. We find that these methods break down at lower bit precision, and investigate quantization aware training for LLMs (LLM-QAT) to push quantization levels even further. We propose a data-free distillation method that leverages generations produced by the pre-trained model, which better preserves the original output distribution and allows quantizing any generative model independent of its training data, similar to post-training quantization methods. In addition to quantizing weights and activations, we also quantize the KV cache, which is critical for increasing throughput and support long sequence dependencies at current model sizes. We experiment with LLaMA models of sizes 7B, 13B, and 30B, at quantization levels down to 4-bits. We observe large improvements over training-free methods, especially in the low-bit settings.

通过提出一种数据无关的蒸馏方法，利用预训练模型生成的结果来实现对语言模型低位量化，包括权重、激活值和KV Cache，该方法比已有的基于训练后量化和无训练量化方法更适用于低精度位级下的大型语言模型。

LLM-QAT: 大型语言模型的无数据量化感知训练