arXiv Machine Learning

TR-PTQ: High-Accuracy Integer-Only Transformer Post Training Quantization via Taylor Region Reformulation

TR-PTQ is a post‑training quantization method that enables high‑accuracy, integer‑only inference for transformer models. It identifies learned scale parameters in LayerNorm and compounded approximations in GELU as the main sources of accuracy loss, while SoftMax is robust to aggressive quantization. By reformulating these operations with shared Taylor Region exponential and logarithm primitives and a calibration‑free, outlier‑aware optimization for LayerNorm, TR‑PTQ eliminates the need for floating‑point units for nonlinearities and achieves less than 1.5% absolute accuracy degradation on vision and language benchmarks.

arXiv AI
Jun 4

Model-Preserving Adaptive Rounding

arXiv:2505. 22988v3 Announce Type: replace-cross Abstract: The goal of quantization is to produce a compressed model whose output distribution is as close to the original model's as possible.

By Albert Tseng, Zhaofeng Sun, Christopher De Sa
arXiv AI
Oct 9

When Lower Reconstruction Loss Hurts: Distributionally Robust Refinement for Low-Bit LLM Quantization

The paper examines weight-only post‑training quantization (PTQ) and finds that minimizing reconstruction loss does not always improve model performance, sometimes even harming it on calibration data. It shows that weights with low reconstruction loss on one distribution can perform worse when activation distributions shift. To address this, the authors introduce Distributionally Robust Quantization (DRQ), a refinement step that minimizes worst‑case reconstruction loss over a constrained set of activation distributions while keeping the quantization grid unchanged. Experiments demonstrate that DRQ improves models quantized by several PTQ methods across dense and mixture‑of‑experts large language models, offering better downstream performance without extra inference cost.

By Yanlong Zhao, Xiaoyuan Cheng, Huihang Liu, Baihua He, Xinyu Zhang, Harrison Bo Hua Zhu, Wenlong Chen, Li Zeng, Zhuo Sun
arXiv AI
Oct 2

The Devil Is in the Reconstruction Loss Scale: Rethinking Optimization in LLM Quantization

The paper investigates how the choice of reconstruction loss, specifically mean squared error (MSE), affects optimization in sequential post‑training quantization (PTQ) of large language models (LLMs). It identifies an Optimization Imbalance where MSE causes reconstruction loss magnitudes—and thus gradient magnitudes—to vary dramatically across quantization stages, leading to uneven parameter updates. The authors propose that root mean squared error (RMSE) variants, which implicitly normalize gradients, can decouple optimization strength from loss scale and outperform MSE as a drop‑in replacement.

By Chao Li, Shigeng Wang, Anbang Yao