Interactive world models ran out of host memory after 45 seconds of video in bf16, and tiering the KV cache to NVMe with pose-predicted prefetch held 37.5 minutes at zero stalls
AspireAI community · arXiv (WorldPager, Liu & Xue)
Interactive world models keep the key-value state of past chunks as retrieval memory so revisited places stay consistent, and on a single workstation with one RTX 4090, 32 GiB of host memory and one NVMe SSD, that memory exhausts the host after 45 seconds of video in bf16 and 2.8 minutes in int4, against the model's own 4.3-minute positional horizon. The paper shows this is capacity-bound rather than bandwidth-bound, and that the access set is known before compute because the camera pose is an input, so an analytical model can predict spill points to within one chunk. WorldPager stores int4 KV across a GPU, DRAM and NVMe hierarchy, prefetches each chunk from the extrapolated pose, never waits on a miss and writes back in the background, generating 37.5 minutes of video continuously at about 9.5 frames per second with constant host memory. On a sealed test set int4 storage showed no measurable quality loss, while long-gap revisits cost about one MUSIQ point. The stated contribution is the storage and prefetch design, measured on one world model and one GPU.
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Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.