ByteDance Research: Chunked KV Compression Means Token Position Determines Whether Information Is Readable
A paper from the ByteDance team reveals that models using chunked KV Cache compression, such as DeepSeek V4, suffer from phase sensitivity issues: a token's position within a compressed chunk determines whether its information is retained.
Asking DeepSeek the same question twice, with only a few extra spaces added, can yield one correct answer and one completely wrong one. A paper released by the ByteDance team in late September, titled "Periodic Weak Spots: Phase Sensitivity from Chunked KV-Cache Compression," reveals the underlying cause of this phenomenon: chunked KV Cache compression technology, while alleviating VRAM pressure, introduces phase sensitivity—a token's position within a compressed chunk determines whether it can be read by the model.