English

An Extra RMSNorm is All You Need for Fine Tuning to 1.58 Bits

Machine Learning 2025-05-15 v1 Artificial Intelligence Computation and Language

Abstract

Large language models (LLMs) have transformed natural-language processing, yet their scale makes real-world deployment costly. Post-training quantization reduces memory and computation but often degrades accuracy, while quantization-aware training can recover performance at the cost of extra training. Pushing quantization to the ternary (2-bit) regime yields even larger savings but is notoriously unstable. Building on recent work showing that a bias-free, RMS-normalized Transformer with straight-through estimation can reach 1.58-bit precision, we demonstrate that simply inserting RMS normalization before every linear projection and applying a gradual, layer-wise quantization schedule stably fine-tunes full-precision checkpoints into ternary LLMs. Our approach matches or surpasses more elaborate knowledge-distillation pipelines on standard language-modeling benchmarks without adding model complexity. These results indicate that careful normalization alone can close much of the accuracy gap between ternary and full-precision LLMs, making ultra-low-bit inference practical.

Keywords

Cite

@article{arxiv.2505.08823,
  title  = {An Extra RMSNorm is All You Need for Fine Tuning to 1.58 Bits},
  author = {Cody Steinmetz and Gavin Childress and Aaron Herbst and Gavin Jones and Jasdeep Singh and Eli Vang and Keagan Weinstock},
  journal= {arXiv preprint arXiv:2505.08823},
  year   = {2025}
}