Tsinghua-NICS releases AKV: KV cache engineering for LLM agents with drop and reposition operations

AKV lets LLM agents manage their key-value cache directly, cutting cost and latency while keeping task accuracy.

HeyHomees Lab Notes · No. 7 · Tsinghua-NICS-EFC · Published October 22, 2026

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In 30 seconds

What is it?

AKV is a cache-engineering system for large language model agents that adds drop and reposition operations to the KV cache, allowing agents to control active cache without modifying the conversation history or re-prefilling retained context.

How does it work?

Agents use a CachePolicy to specify which messages’ KV entries to drop (drop_message) and when to compact token positions (reposition). The AKV serving engine provides a stateless API that internally manages cache reuse, eviction, and restoration while remaining compatible with existing OpenAI-compatible serving APIs.

How well does it do?

A tool-response rolling-drop policy raises average benchmark scores by 1.7 points and lowers average cost by 27.7% versus threshold-triggered summarization. AKV also reaches up to 1.2× output throughput and a 1.5× speedup in P95 request latency, and recursive self-improvement of cache policies adds a further 7.1% cost reduction.

What does it need to run?

Running AKV requires Rust and Cargo, a Python virtual environment, the SGLang inference system, and an LLM such as GPT-OSS-120B served via an OpenAI-compatible Chat Completions API.

By the numbers

The honest read

The reported improvements—1.7-point score gain, 27.7% cost cut, 1.2× throughput, and 1.5× latency speedup—are self-reported by the authors and measured on their internal benchmarks; the paper does not provide external validation or comparison to other cache-management methods. The figures reflect average results and a maximum throughput gain, not guaranteed performance across all workloads. Recursive policy gains add an extra 7.1% cost reduction, but this is described as “further reduces cost” without a baseline, so the absolute impact is unclear.

What we don't know yet

Sources

Researched and drafted with AI from the sources above; every figure is checked against them by code before it is published, and a line that fails is dropped.

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