English

TurboAngle: Near-Lossless KV Cache Compression via Uniform Angle Quantization

Machine Learning 2026-03-31 v1 Artificial Intelligence

Abstract

We compress KV cache entries by quantizing angles in the Fast Walsh-Hadamard domain, where a random diagonal rotation makes consecutive element pairs approximately uniformly distributed on the unit circle. We extend this angular quantizer with per-layer early-boost, which independently configures K and V codebook sizes at each layer, allocating higher precision to a model-specific subset of critical layers. Across seven models (1B to 7B parameters), per-layer early-boost achieves lossless compression on four models and near-lossless quality on six of seven, at 3.28 to 3.67 angle bits per element. Asymmetric norm quantization (8-bit for keys, 4-bit log-space for values) yields 6.56 total bits per element on Mistral-7B with perplexity degradation of +0.0014 and no calibration data. A layer-group sensitivity analysis reveals model-specific bottleneck patterns, including K-dominated versus V-dominated layers and negative-transfer layers where increased precision degrades quality.

Keywords

Cite

@article{arxiv.2603.27467,
  title  = {TurboAngle: Near-Lossless KV Cache Compression via Uniform Angle Quantization},
  author = {Dipkumar Patel},
  journal= {arXiv preprint arXiv:2603.27467},
  year   = {2026}
}

Comments

10 pages, 7 tables, 2 figures

R2 v1 2026-07-01T11:42:35.313Z