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arXiv · 2602.01519

You Need an Encoder for Native Position-Independent Caching

Shiju Zhao·Junhao Hu·Jiaqi Zheng·Guihai Chen
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Abstract

The Key-Value (KV) cache of Large Language Models (LLMs) is prefix-based, making it highly inefficient for processing contexts retrieved in arbitrary order. Position-Independent Caching (PIC) has been proposed to enable KV reuse without positional constraints; however, existing approaches often incur substantial accuracy degradation, limiting their practical adoption. To address this issue, we propose native PIC by reintroducing the encoder to prevalent decoder-only LLMs and explicitly training it to support PIC. We further develop COMB, a PIC-aware caching system that integrates seamlessly with existing inference frameworks. Experimental results show that COMB reduces Time-to-First-Token (TTFT) by 51-94% and increases throughput by 3$\times$ with comparable accuracy. Furthermore, the quality improvement when using DeepSeek-V2-Lite-Chat demonstrates the applicability of COMB to other types of decoder-only LLMs. Our code is available at https://github.com/shijuzhao/Comb.

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Shiju Zhao, Junhao Hu, Jiaqi Zheng, Guihai Chen. 2026-02-02. You Need an Encoder for Native Position-Independent Caching. https://arxiv.org/abs/2602.01519

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