低资源语言下推测解码效果差,小模型多语言能力不足是主因
Speculative Decoding and the Curse of Multilinguality
- 用小模型做推测解码,但低资源语言支持弱
- 11种语言实验验证:低资源语言速度提升不明显
- 提出轻量n-gram模型,虽慢但推理开销极小
推测解码是提升大语言模型推理速度的常用技术,通过小型草稿模型预生成多个词元。然而,该技术的有效性主要在英语中被验证。受多语言诅咒启发,我们假设小模型在低资源语言上的多语言能力有限,导致推测解码效果较差。我们在标准设置下测试了11种语言,发现有力证据支持该假设。随后,尝试通过从大模型蒸馏来增强小模型的多语言能力,却发现跨任务泛化性能差,且对低资源语言难以构建任务无关的全代表数据集。最后,我们提出使用更弱的n-gram模型作为草稿模型,因其极低的推理开销,可实现适度加速。
原文摘要 · Abstract (English)
Speculative decoding is a popular technique for large language model (LLM) inference, enabling faster generation by drafting multiple tokens with a smaller draft model. However, the effectiveness of speculative decoding has mainly been studied for English. Motivated by the curse of multilinguality, we hypothesize that speculative decoding is far less effective for low-resource languages due to the limited multilingual capacities of smaller models. We test eleven languages under a standard speculative decoding setup and find strong evidence for our hypothesis. Next, we try to improve the multilingual capabilities of the smaller draft model via distillation from the larger model. We find, though, that distillation generalizes poorly across tasks in the same language, and we argue that assembling a task-agnostic, fully representative dataset is infeasible for low-resource languages. Finally, we propose weaker n-gram models as draft models; these provide moderate speed-ups due to their minuscule inference cost.
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