arXiv Machine Learning By Lan Wu, Bruce Changlong Xu

Behavioral Consistency in Machine Learning

Read the original on arXiv Machine Learning →

The paper investigates how identical model weights can yield different next‑token distributions when run by different serving programs, due to variations in precision, kernel implementation, and batching. It introduces the concept of kernel contracts that bound how much a serving kernel may deviate from a reference kernel on each traffic slice, and proves non‑asymptotic bounds linking logit differences to divergence metrics, reward changes, policy‑gradient bias, and greedy‑token flips. Experiments on Qwen2.5‑7B‑Instruct confirm that these bounds hold across prompts and that precision or engine changes can alter token outputs, especially on undecided prompts, highlighting the need for per‑slice contract checks.

Machine-generated by The Flow from the publisher's headline and feed description — not written or checked by a human. The full article lives at arXiv Machine Learning.

arXiv AI
Jun 9

Training-Inference Kernel Contracts: Bounding Divergence in Post-Training and Deployment

arXiv:2606. 07581v1 Announce Type: cross Abstract: A modern post-training pipeline often writes one symbol for its policy, pi_theta, while evaluating it through two different programs: a training kernel optimized for autograd and an inference kernel optimized for low-precision, fused, dynamically batched serving.

By Bruce Changlong Xu, Lan Wu
arXiv Machine Learning
6d ago

ScaleRLT: Exact Log-Probabilities and Fast Deferred Rollouts for Reinforcement Learning on Looped Transformers

ScaleRLT introduces a hybrid learner log‑probability method that reconciles differences between dense and deferred rollout computations in looped language models like Ouro. By using a stop‑gradient replay of the rollout schedule, the approach achieves bit‑for‑bit reproducibility across FP32 and bf16 real‑weight cells while maintaining the same gradient accuracy as dense implementations. The technique boosts rollout throughput by up to 1.56× on a single GPU and significantly speeds up multi‑node GRPO updates, leading to substantial accuracy gains on GSM8K in short training runs.

By Dezhen Lu, Zixiang Ni, Runguo Li
arXiv Machine Learning
6d ago

End-to-End MXFP8 Reinforcement Learning on Blackwell: What Matching Buys, When It Pays Off, and How It Fails

The paper presents an end‑to‑end MXFP8 reinforcement learning implementation on Blackwell GPUs, evaluating its benefits and limitations with Qwen3-8B and Qwen3-30B-A3B models. It finds that matching FP8 precision between sampler and learner improves consistency, that speed gains appear only for large micro‑batches, and that several weight‑synchronization correctness conditions can fail silently. The study also introduces seven explicit checks to detect such failures during training.

By Wengee Zhang
Hugging Face Trending Papers
Jul 21

Stale but Stable: Staleness-Adaptive Trust Regions for Stabilizing Asynchronous Reinforcement Learning

Asynchronous reinforcement learning improves throughput by decoupling rollout generation from optimization, but staleness is an inevitable byproduct compounded by policy lag, engine delays, and mixture-of-experts routing. From a trust-region perspective, this mismatch is critical: training-inference divergence governs approximation error in finite-horizon bounds, whereas PPO clipping only gates sampled outward updates, acting as a sampled surrogate rather than a full-policy constraint.

arXiv Machine Learning
Jul 22

Stale but Stable: Staleness-Adaptive Trust Regions for Stabilizing Asynchronous Reinforcement Learning

arXiv:2607. 18722v1 Announce Type: new Abstract: Asynchronous reinforcement learning improves throughput by decoupling rollout generation from optimization, but staleness is an inevitable byproduct compounded by policy lag, engine delays, and mixture-of-experts routing.

By Junyao Yang, Yucheng Shi, Zongxia Li, Zhongzhi Li, Ruhan Wang, Xiangxin Zhou, Kishan Panaganti, Haitao Mi, Leowei Liang