arXiv AI

Layerwise Repacking: Variable-Length Hybrid-Attention Training without an Extra Redistribution Pass

The paper introduces Layerwise Repacking, a technique that eliminates an extra data redistribution step when training hybrid‑attention models with variable‑length sequences. By keeping full‑attention layers in wide sequence‑parallel groups (SP16/32) and repacking samples into node‑local sparse children (SP1/2/4/8) within the same all‑to‑all communication, the method preserves hidden‑state continuity and avoids costly inter‑node transfers. Experiments on a 1F3S hybrid‑attention model show that repacking alone cuts end‑to‑end training time by ~6 % and boosts FLOP utilization, with an improved solver further reducing time by ~7.6 % and increasing utilization by ~4.8 %.

arXiv AI
Jul 22

A Controlled Study of Attention-Only Transformers

arXiv:2607. 18363v1 Announce Type: cross Abstract: Feed-forward networks hold two thirds of a transformer's non-embedding parameters, yet the architecture has not received a necessity test that controls parameters, compute, and depth at once.

By Henry Ndubuaku, Karen Mosoyan, Jakub Mroz, Noah Cylich, Satyajit Kumar, Parkirat Sandhu, Roman Shemet, Justin H Lee
arXiv AI
Oct 12

Kairos: Toward a Byte-Level Foundation Model for Every Modality

Kairos is a byte‑level foundation model that integrates bidirectional gated‑DeltaNet linear attention, sliding‑window attention, block‑wise Attention‑Residual aggregation, a sparse Mixture‑of‑Experts feed‑forward layer, and a multi‑scale byte‑level codec. It is trained with a uniform‑noise denoising objective over a single byte space shared by text, image, audio, video, lidar, and control streams, and the authors provide code‑derived algorithms for each component, including a cross‑session recurrent‑state memory gate. Convergence sanity checks on a 440‑byte text sentence show that the two attention variants reach a minimum loss near 10⁻³, and the implementation appears to optimize, though generalization and multimodal performance remain to be evaluated in future pretraining runs.

By Fabien Furfaro
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 Machine Learning
Jul 20

DualKV: Shared-Prompt Flash Attention for Efficient RL Training with Large Rollouts and Long Contexts

arXiv:2605. 15422v3 Announce Type: replace Abstract: Modern RL post-training methods such as GRPO and DAPO train on N response sequences of R tokens sampled from a shared prompt of P tokens, but standard FlashAttention replicates all P prompt tokens N times across both forward and backward passes -- duplicating compute and memory on identical hidden states.

By Jiading Gai, Shuai Zhang, Xiang Song, Bernie Wang, George Karypis
arXiv AI
Jun 12

MiniMax Sparse Attention

arXiv:2606. 13392v1 Announce Type: new Abstract: Ultra-long-context capability is becoming indispensable for frontier LLMs: agentic workflows, repository-scale code reasoning, and persistent memory all require the model to jointly attend over hundreds of thousands to millions of tokens, yet the quadratic cost of softmax attention makes this untenable at deployment scale.

By Xunhao Lai, Weiqi Xu, Yufeng Yang, Qiaorui Chen, Yang Xu, Lunbin Zeng, Xiaolong Li, Haohai Sun, Haichao Zhu, Vito Zhang, Pengyu Zhao
arXiv AI
Oct 21

MLIPS: Multi-Layer Indexer Pool Sharing

arXiv:2610.27438v1 Announce Type: cross Abstract: Sparse attention limits the keys used by each query, but finding those keys can still require a full-prefix scan at every layer. We introduce \textbf...

By Samkit Jain, Sai Kishan Pampana, Shlok Agarwal