Large language models (LLMs) show excellent performance but are compute- and memory-intensive. Quantization can reduce memory and accelerate inference. However, for LLMs beyond 100 billion parameters, existing methods cannot maintain accuracy or do not run efficiently on hardware. We propose SmoothQuant, a training-free, accuracy-preserving, and general-purpose post-training quantization (PTQ) solution to enable 8-bit weight, 8-bit activation (W8A8) quantization for LLMs that can be implemented efficiently. We observe that systematic outliers appear at fixed activation channels. Based on the fact that weights are easy to quantize while activations are not, SmoothQuant smooths the activation outliers by migrating the quantization difficulty from activations to weights with a mathematically equivalent transformation. SmoothQuant enables an INT8 quantization of both weights and activations for all the GEMMs in LLMs, including OPT-175B, BLOOM-176B and GLM-130B. SmoothQuant has better hardware efficiency than existing techniques using mixed-precision activation quantization or weight-only quantization. We demonstrate up to 1.56x speedup and 2x memory reduction for LLMs with negligible loss in accuracy. Thanks to the hardware-friendly design, we integrate SmoothQuant into FasterTransformer, a state-of-the-art LLM serving framework, and achieve faster inference speed with half the number of GPUs compared to FP16. Our work offers a turn-key solution that reduces hardware costs and democratizes LLMs. Code will be released at: https://github.com/mit-han-lab/smoothquant.

SmoothQuant是一个训练免费的精度保持、通用的后训练量化解决方案，用于大型语言模型（LLMs），通过平滑激活异常值并在权重和激活之间进行数学上等效的变换以迁移量化难度，可以实现LLMs的8位权重和激活（W8A8）量化，同时提高硬件效率，以较小的精度损失实现高达2倍的内存减少和1.56倍的加速，是一个可降低硬件成本、民主化LLMs的一站式解决方案。

SmoothQuant：大型语言模型后训练量化的准确高效算法