Beyond Token Eviction: Mixed-Dimension Budget Allocation for Efficient KV Cache Compression

Fuente: arXiv
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Autores principales: Miao, Ruijie, Wang, Zhiming, Li, Wang, Wu, Shiwei, Liu, Shufan, Jiang, Yanbing, Yang, Tong
Formato: Preprint
Publicado: 2026
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author Miao, Ruijie
Wang, Zhiming
Li, Wang
Wu, Shiwei
Liu, Shufan
Jiang, Yanbing
Yang, Tong
author_facet Miao, Ruijie
Wang, Zhiming
Li, Wang
Wu, Shiwei
Liu, Shufan
Jiang, Yanbing
Yang, Tong
contents Key-value (KV) caching is widely used to accelerate transformer inference, but its memory cost grows linearly with input length, limiting long-context deployment. Existing token eviction methods reduce memory by discarding less important tokens, which can be viewed as a coarse form of dimensionality reduction that assigns each token either zero or full dimension. We propose MixedDimKV, a mixed-dimension KV cache compression method that allocates dimensions to tokens at a more granular level, and MixedDimKV-H, which further integrates head-level importance information. Experiments on long-context benchmarks show that MixedDimKV outperforms prior KV cache compression methods that do not rely on head-level importance profiling. When equipped with the same head-level importance information, MixedDimKV-H consistently outperforms HeadKV. Notably, our approach achieves comparable performance to full attention on LongBench with only 6.25% of the KV cache. Furthermore, in the Needle-in-a-Haystack test, our solution maintains 100% accuracy at a 50K context length while using as little as 0.26% of the cache.
format Preprint
id arxiv_https___arxiv_org_abs_2603_20616
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Beyond Token Eviction: Mixed-Dimension Budget Allocation for Efficient KV Cache Compression
Miao, Ruijie
Wang, Zhiming
Li, Wang
Wu, Shiwei
Liu, Shufan
Jiang, Yanbing
Yang, Tong
Machine Learning
Key-value (KV) caching is widely used to accelerate transformer inference, but its memory cost grows linearly with input length, limiting long-context deployment. Existing token eviction methods reduce memory by discarding less important tokens, which can be viewed as a coarse form of dimensionality reduction that assigns each token either zero or full dimension. We propose MixedDimKV, a mixed-dimension KV cache compression method that allocates dimensions to tokens at a more granular level, and MixedDimKV-H, which further integrates head-level importance information. Experiments on long-context benchmarks show that MixedDimKV outperforms prior KV cache compression methods that do not rely on head-level importance profiling. When equipped with the same head-level importance information, MixedDimKV-H consistently outperforms HeadKV. Notably, our approach achieves comparable performance to full attention on LongBench with only 6.25% of the KV cache. Furthermore, in the Needle-in-a-Haystack test, our solution maintains 100% accuracy at a 50K context length while using as little as 0.26% of the cache.
title Beyond Token Eviction: Mixed-Dimension Budget Allocation for Efficient KV Cache Compression
topic Machine Learning
url https://arxiv.org/abs/2603.20616