Probing the Prompt KV Cache: Where It Becomes Dispensable
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Computer Science > Computation and Language
Title:Probing the Prompt KV Cache: Where It Becomes Dispensable
Abstract:Prior KV cache compression schemes empirically demonstrate that the prompt cache is partially redundant during decoding, dropping or summarising entries with little accuracy loss. We ask when and what kind of redundancy: at which layers, after how many decoding steps, and in what form can the prompt span KV cache be replaced without breaking the task. A controlled splice intervention swept over layer cutoff and decoding steps shows this redundancy is about form (chat template scaffolding) rather than content. Replacing the upper layer prompt span KV cache with KV cache from a chat template scaffold whose user content is a neutral filler recovers near clean accuracy, while zeroing the same slots collapses accuracy. The dissociation replicates across the Qwen3, Gemma 3, and Llama 3 families on multiple datasets.
| Subjects: | Computation and Language (cs.CL) |
| Cite as: | arXiv:2605.30574 [cs.CL] |
| (or arXiv:2605.30574v1 [cs.CL] for this version) | |
| https://doi.org/10.48550/arXiv.2605.30574
arXiv-issued DOI via DataCite (pending registration)
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Submission history
From: Vinayshekhar Bannihatti Kumar [view email][v1] Thu, 28 May 2026 21:07:41 UTC (3,854 KB)
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