通过动态控制减少冗余计算,加速扩散语言模型生成。
Efficient Diffusion LLMs via Temporal-Spatial Parallel Decoding and Confidence Extrapolation

- 利用逐标记轨迹特征实现时空并行解码,判断何时可固定输出。
- 提出无训练状态空间模块,预测未来逻辑趋势以提前决策。
- 适合追求推理速度且对生成质量要求高的实际应用者。
基于扩散的大型语言模型(dLLMs)通过迭代去噪实现并行文本生成,但推理延迟高,因大量步骤用于冗余精炼和重复遮蔽已确定值的标记。现有加速方法依赖局部置信度启发式或固定调度,对提示和任务变化敏感,且忽略序列内强位置效应。本文将扩散解码建模为动态控制问题,发现逐标记去噪轨迹是可靠控制的关键信号。提出一种轨迹感知解码框架,包含两个组件:首先,时间-空间并行解码(TSPD)使用轻量级时空控制器,结合每个标记的置信度、熵、动量及位置信息,判断其是否收敛并可安全固定;其次,引入无需训练的状态空间模块——置信度外推(CE),通过预测未来逻辑趋势与不确定性,支持前瞻决策,包括安全前瞻和轨迹振荡或低置信时的针对性稳定。TSPD与CE协同减少不必要的去噪迭代,同时保持输出质量,并可与键值缓存等系统优化无缝集成。
原文摘要 · Abstract (English)
Diffusion-based large language models (dLLMs) support parallel text generation via iterative denoising, yet inference remains latency-heavy because many steps are spent on redundant refinement and repeated remasking of tokens whose final values are already determined. Prior acceleration methods mainly depend on step-local confidence heuristics or fixed schedules, which are sensitive to prompt and task variation and ignore strong positional effects within a sequence. We cast diffusion decoding as a dynamic control problem and show that token-wise denoising trajectories provide the key signal for reliable control. We propose a trace-aware decoding framework with two components. First, Temporal-Spatial Parallel Decoding (TSPD) uses a lightweight temporalspatial controller that consumes per-token trajectory features, including confidence, entropy, and momentum, together with token position, to decide when a token has converged and can be safely fixed. Second, we introduce Confidence Extrapolation (CE), a training-free state-space module that forecasts future logit trends with uncertainty to support proactive decisions, including safe look-ahead and targeted stabilization when trajectories are oscillatory or underconfident. Together, TSPD and CE reduce unnecessary denoising iterations while preserving output quality, and they compose cleanly with system optimizations such as KV caching.
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