KV Cache Quantization Asymmetry
KV cache quantization is the only pain-free memory saving the project found for long context. A sweep over bits, granularity, and the K/V ratio on GPT-2 showed that keys need more bits than values. Porting the test to Qwen3.5 exposed a measurement-location artifact and showed the asymmetry is regime-dependent, not universal: keys win decisively below ~4 effective bits, while above ~5 the choice is domain-dependent.
GPT-2 small · Qwen3.5