Rotation-Aligned Key Channel Pruning for Efficient Vision-Language Model Inference

Fuente: arXiv
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Autores principales: Kang, Beomseok, Jo, Dongwon, Song, Jiwon, Son, Donghwee, Kim, Jae-Joon
Formato: Preprint
Publicado: 2026
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author Kang, Beomseok
Jo, Dongwon
Song, Jiwon
Son, Donghwee
Kim, Jae-Joon
author_facet Kang, Beomseok
Jo, Dongwon
Song, Jiwon
Son, Donghwee
Kim, Jae-Joon
contents Vision-Language Models suffer severe KV cache pressure at inference, as a single image often encodes into thousands of tokens. Most existing methods exploit token sparsity through token pruning, but permanently discarding visual content causes substantial degradation on fine-grained perception tasks. This motivates a complementary axis, feature sparsity: under a fixed KV cache budget, compressing the channel dimension preserves more visual tokens at the same memory cost. Prior Key channel pruning methods, however, face a structural trade-off: token-wise channel pruning is expressive but unstructured and slow, while head-wise approach is hardware-friendly but less robust. We resolve this with RotateK, a rotation-based structured Key channel pruning framework. RotateK applies an online PCA-based rotation that aligns token-dependent channel importance into a shared low-dimensional subspace, enabling accurate pruning under lightweight head-wise masks; a fused Triton attention kernel operates directly on sparse-channel Keys for efficient decoding. Experiments on two representative VLM backbones show that RotateK consistently outperforms prior Key channel pruning in both accuracy and decoding latency, while joint token-channel pruning improves over token-only baselines at matched KV cache budgets.
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publishDate 2026
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spellingShingle Rotation-Aligned Key Channel Pruning for Efficient Vision-Language Model Inference
Kang, Beomseok
Jo, Dongwon
Song, Jiwon
Son, Donghwee
Kim, Jae-Joon
Computer Vision and Pattern Recognition
Artificial Intelligence
Vision-Language Models suffer severe KV cache pressure at inference, as a single image often encodes into thousands of tokens. Most existing methods exploit token sparsity through token pruning, but permanently discarding visual content causes substantial degradation on fine-grained perception tasks. This motivates a complementary axis, feature sparsity: under a fixed KV cache budget, compressing the channel dimension preserves more visual tokens at the same memory cost. Prior Key channel pruning methods, however, face a structural trade-off: token-wise channel pruning is expressive but unstructured and slow, while head-wise approach is hardware-friendly but less robust. We resolve this with RotateK, a rotation-based structured Key channel pruning framework. RotateK applies an online PCA-based rotation that aligns token-dependent channel importance into a shared low-dimensional subspace, enabling accurate pruning under lightweight head-wise masks; a fused Triton attention kernel operates directly on sparse-channel Keys for efficient decoding. Experiments on two representative VLM backbones show that RotateK consistently outperforms prior Key channel pruning in both accuracy and decoding latency, while joint token-channel pruning improves over token-only baselines at matched KV cache budgets.
title Rotation-Aligned Key Channel Pruning for Efficient Vision-Language Model Inference
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2605.19218