Training-free geometric KV routing cuts Qwen memory traffic by 16x

Electrical_Offer5667 · reddit · 2026-08-22

A training-free geometric KV routing method for frozen Qwen models assigns expired KV entries to centroid-represented regions, computing attention only over {sinks + recent window + selected regions}. Tests on Qwen3.5-2B (32k) and Qwen3-4B (8k) show 3.7x to 31x fewer physical KV reads while maintaining retrieval capabilities. Although wall-clock speed doesn't yet beat optimized dense attention due to GPU brute force and routing overhead, it highlights potential for reducing memory bandwidth and capacity in long-context scenarios. A GitHub demo is available.

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