arXiv:2508.05165cs.LGcs.AI2025-08

用轻量方法在低算力下实现大模型对齐,兼顾效果与成本。

Aligning LLMs on a Budget: Inference-Time Alignment with Heuristic Reward Models

  • 用启发式奖励模型+两阶段过滤,减少推理次数
  • 在少至1~2次响应下仍保持对齐效果
  • 适合资源受限场景的个性化大模型部署

将大语言模型与用户偏好对齐对实际应用至关重要,但通常需要昂贵的微调或高成本推理,导致对齐质量与计算开销之间难以平衡。现有推理时对齐方法往往忽略这一权衡,仅关注优化策略的性能表现。本文提出HIA(Heuristic-Guided Inference-time Alignment),一种无需调参、兼容黑盒的方案,结合轻量级提示优化器、启发式奖励模型和两阶段过滤机制,在不增加计算负担的前提下减少推理调用次数,同时保持对齐质量。在真实提示数据集HelpSteer和ComPRed上,HIA在相同推理预算下,优于最佳N采样、束搜索和贪婪搜索基线,在多目标、目标条件任务中表现更优。此外,即使在极低推理预算(仅需1~2次响应)下,HIA仍具有效性,为可扩展、个性化的大型语言模型部署提供实用解决方案。

原文摘要 · Abstract (English)

Aligning LLMs with user preferences is crucial for real-world use but often requires costly fine-tuning or expensive inference, forcing trade-offs between alignment quality and computational cost. Existing inference-time methods typically ignore this balance, focusing solely on the optimized policy's performance. We propose HIA (Heuristic-Guided Inference-time Alignment), a tuning-free, black-box-compatible approach that uses a lightweight prompt optimizer, heuristic reward models, and two-stage filtering to reduce inference calls while preserving alignment quality. On real-world prompt datasets, HelpSteer and ComPRed, HIA outperforms best-of-N sampling, beam search, and greedy search baselines in multi-objective, goal-conditioned tasks under the same inference budget. We also find that HIA is effective under low-inference budgets with as little as one or two response queries, offering a practical solution for scalable, personalized LLM deployment.

大模型对齐推理优化低成本部署

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