arXiv Computation and Language

Performance-Driven Policy Optimization for Speculative Decoding with Adaptive Windowing

arXiv Computation and Language
Sep 4

Margins, Not Windows: Training-Free Per-Step Lossy Speculative Decoding

The paper introduces AdaptiveSpec, a training‑free speculative decoding method that simultaneously adapts the per‑step verification rule and the draft‑tree shape using signals generated during decoding. It replaces the fixed token‑match rule with a margin‑based threshold and adjusts tree depth, width, and node count based on draft confidence and recent acceptance history, allowing the total draft count to vary. Experiments on SGLang show up to 56% throughput gains over EAGLE‑3 while maintaining 93% of lossless task accuracy on GSM8K, MATH‑500, and HumanEval across three models.

By Oszk\'ar Urb\'an, Young D. Kwon, Stylianos I. Venieris, Cecilia Mascolo
arXiv Machine Learning
Oct 8

Training Parallel Speculative Draft Models by Directly Minimizing Expected Decoding Rounds

The paper introduces the Expected Decoding Rounds (EDR) objective, a theoretical framework that models speculative decoding as a Markov reward process and directly optimizes the number of decoding rounds. EDR weights local rejection costs by state occupancies, eliminating auxiliary hyperparameters and enabling unbiased stochastic optimization via temporal‑difference gradients. Applying EDR to fine‑tune state‑of‑the‑art draft models (DSpark and DFly) improves mean accepted length and outperforms prior training objectives across nine benchmarks in math reasoning, code generation, and chat.

By Yunxiao Zhao, Changxiao Cai
arXiv AI
Aug 7

When Drafts Evolve: Speculative Decoding Meets Online Learning

arXiv:2603. 12617v2 Announce Type: replace-cross Abstract: Speculative decoding has emerged as a widely adopted paradigm for accelerating large language model inference, where a lightweight draft model rapidly generates candidate tokens that are then verified in parallel by a larger target model.

By Yu-Yang Qian, Hao-Cong Wu, Yichao Fu, Hao Zhang, Peng Zhao
arXiv Machine Learning
3d ago

SP$^2$ec: Adaptive Self-Speculative Decoding for Vision-Language Models

SP$^2$ec is a training‑free bandit algorithm that adapts the draft configuration during generation for Vision‑Language Models, exploiting a single‑peak throughput pattern observed in existing self‑speculative methods. It minimizes a novel wall‑time regret metric, theoretically guaranteeing near‑optimal draft selection with negligible exploration cost. Experiments on Qwen2.5‑VL‑7B‑Instruct and LLaVA‑Next‑Mistral‑7B show consistent improvements of up to 11% over prior self‑speculative methods across visual and textual tasks.

By Yuqi Huang, Xingyao Li, Yunlong Hou, Fengzhuo Zhang, Jiachun Pan, Vincent Y. F. Tan
arXiv Computation and Language
Sep 23

TSS: Target-Side Sparsification for Speculative Decoding in Domain-Specific Large Language Models

The paper introduces TSS, a target-side sparsification framework that selectively skips layers in a target verifier during speculative decoding for domain-specific large language models. By exploring multi-layer skip configurations with an acceptance- and metric-aware breadth search, TSS reduces verification cost, increases draft acceptance, and can even improve downstream task performance without retraining. Experiments on Spec-Bench demonstrate consistent gains across domains and model scales, notably boosting translation throughput by 1.68× and improving BLEU scores significantly.

By Haibo Hu, Lianming Huang, Qiao Li, Nan Guan, Chun Jason Xue