arXiv Machine Learning

DeltaS: Reading the Gated Linear Attention State for KV Cache Eviction in Streaming Video

DeltaS is a query‑agnostic, training‑free method for evicting key‑value cache entries in hybrid video‑language models that combine linear and full attention. It uses the change in the recurrent state of gated‑delta linear attention—called state drift—to decide which video chunks to keep, selecting those that induce larger normalized state changes. In experiments with a fixed memory budget, DeltaS outperforms position‑, attention‑, and key‑value‑based eviction signals, improving performance by 2.1 points on average across six long‑video benchmarks and 5.6 points on the longest benchmark, while adding only 1.9% of the forward‑pass cost.

arXiv Machine Learning
Sep 14

Fixed State, Long Reach: What a Constant-Size Cache Buys Block Diffusion at Scale

The paper investigates how block‑diffusion language models can use a constant‑size cache to enable efficient parallel decoding. By employing sequence mixers that summarize completed blocks into a reusable state and a block‑causal training objective, the authors pretrain three 3B block‑diffusion denoisers (attention, Mamba, and hybrid) on 300 B tokens. The resulting state‑space cache remains O(1) in memory and latency regardless of context length, yielding significant speed‑up and memory savings compared to traditional attention‑based caches, especially at very long sequences.

By Vaibhav Singh, Pierre-Andr\'e No\"el, Torsten Scholak, Eugene Belilovsky, Oleksiy Ostapenko
arXiv Computer Vision
Aug 31

DensityKV: Density-Guided KV Cache Compression for Long Video Generation

DensityKV is a training‑free strategy for managing the historical key‑value (KV) cache in autoregressive video diffusion models. It creates a separate token‑level KV bank for each attention head and uses Soft‑Riesz density to measure and limit local redundancy among post‑RoPE keys, thereby preventing the KV archive from growing indefinitely. Experiments on three video generation backbones demonstrate that, with the same KV capacity limit, DensityKV improves long‑horizon consistency and generation stability while keeping persistent storage bounded regardless of rollout length.

By Wenqu Zhao, Xuemin Chi, Xin Zhang, Guoqing Ma, Baorun Li, Jianjie Fang, Peizhi Tang, Chen Gao, Wei Wu