arXiv:2509.03054cs.LGcs.AI2025-09

无需校准和变换,实现4比特权重量化,显著降低部署成本。

Calibration and Transformation-Free Weight-Only LLMs Quantization via Dynamic Grouping

  • 动态分组优化,自适应生成多尺度量化级别。
  • 4比特块级量化下,WikiText-2上困惑度8.43,接近全精度7.81。
  • 纯CPU实现,无需校准数据或中间转换,适合资源受限场景。

大语言模型性能强大,但部署时受内存与算力限制。低比特后训练量化(PTQ)是可行方向,但通常依赖校准数据、辅助变换及GPU工具。为此,我们提出MSB(多尺度二值化),一种无需校准和变换的PTQ方法,将二值量化推广至多比特设置。MSB通过最小化组内方差的动态分组准则,生成跨粒度(从张量到每行64元素块)的一致多尺度量化层级,无需校准或中间变换。量化步骤在基于CPU的求解器中实现,评估采用标准bfloat16执行,不使用低比特打包。在Llama 3.2 3B模型上,MSB在4比特权重仅量化块级配置下,于WikiText-2上达到8.43的困惑度,相比全精度7.81略有下降,优于默认设置下的GPTQ(12.23)。整体上,MSB为低比特PTQ提供新优化视角,并简化了部署流程。

原文摘要 · Abstract (English)

Large Language Models (LLMs) deliver strong performance but are difficult to deploy under tight memory and compute constraints. Low-bit post-training quantization (PTQ) is a promising direction; however, it typically relies on calibration data, auxiliary transformations, and GPU tools. To address these limitations, we propose MSB (Multi Scale Binary), a calibration-free and transformation-free PTQ method that generalizes binary quantization to multi-bit settings. MSB optimizes a dynamic grouping criterion that minimizes within group variance, yielding group-wise multiscale levels that can be applied consistently across granularities from per tensor to block-wise configurations with 64 elements groups per row, without calibration or intermediate transforms. We implement the optimization in a CPU based solver for the quantization step and evaluate using standard bfloat16 execution without low-bit packing. On Llama 3.2 3B, MSB achieves 8.43 perplexity on WikiText-2 under 4-bit weight only block-wise quantization, compared to 7.81 in full precision and 12.23 with GPTQ its default setup. Overall, MSB provides a new optimization perspective for low-bit PTQ while simplifying the pipeline by removing calibration and transformations.

量化LLM部署无校准块级量化

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