arXiv:2601.11564cs.CLcs.AI2026-01被引 2

研究大模型在长文本中性能如何随上下文变长而下降

Context Discipline and Performance Correlation: Analyzing LLM Performance and Quality Degradation Under Varying Context Lengths

  • 分析密集Transformer模型在大量无关上下文下的表现变化
  • 发现KV缓存增长导致性能非线性下降,尤其在长上下文时
  • 揭示MoE架构在超长上下文下被硬件瓶颈掩盖优势

大型语言模型(LLMs)的扩展趋势倾向于增大最大上下文窗口,以支持复杂推理和长文档分析。然而,管理扩展后的上下文会带来严重的计算开销。本文研究了在面对大量无关和干扰性上下文时,密集Transformer架构(特别是Llama-3.1-70B和Qwen1.5-14B)在系统性能与模型质量之间的关键权衡。研究发现,随着键值(KV)缓存的增长,性能出现非线性退化。此外,对混合专家(MoE)架构的扩展分析揭示了不同上下文规模下的独特行为异常,表明在高令牌量下,架构优势可能被基础设施瓶颈所掩盖。

原文摘要 · Abstract (English)

The scaling trend in Large Language Models (LLMs) has prioritized increasing the maximum context window to facilitate complex, long-form reasoning and document analysis. However, managing this expanded context introduces severe computational overhead. This paper investigates the critical trade-off between system performance and model quality when dense transformer architectures--specifically Llama-3.1-70B and Qwen1.5-14B--are exposed to large volumes of irrelevant and distracting context. The research identifies a non-linear performance degradation tied to the growth of the Key-Value (KV) cache. Furthermore, an extended analysis of the Mixture-of-Experts (MoE) architecture reveals unique behavioral anomalies at varying context scales, suggesting that architectural benefits may be masked by infrastructure bottlenecks at high token volumes.

大模型上下文长度性能退化

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