8-bit KV cache nearly free, 4-bit risky: Qwen3.8 27B test data
A benchmark across 35 weight quantizations with llama.cpp, ExLlamaV3 and vLLM measures the KL divergence introduced by quantized KV caches. At 8-bit, memory drops by about 1.9-2 GiB at 64k tokens and the effect on token distribution is nearly zero. 4...