arXiv:2512.04476cs.LGcs.AR2025-12被引 1

用CXL-NDP系统动态调度专家模型,提升大模型推理速度

Context-Aware Mixture-of-Experts Inference on CXL-Enabled GPU-NDP Systems

  • 根据预填充阶段激活统计,智能分配专家到GPU或CXL-NDP执行
  • 实现8.7倍吞吐提升,仅损失0.13%准确率
  • 适合需要高并发、低延迟推理的AI服务场景

Mixture-of-Experts(MoE)模型通过条件计算扩展大语言模型,但当专家权重超过GPU内存容量时,推理会受内存限制。此时需将权重卸载至外部内存,频繁访问带来高昂开销。本文采用连接CXL的近数据处理(CXL-NDP)作为卸载层,在原地执行冷专家,将昂贵的参数移动转化为更廉价的激活移动。与以往大多上下文无关、被动响应的GPU-NDP系统不同,本文提出上下文感知的MoE系统:利用预填充阶段的激活统计指导解码阶段的专家部署,动态将热专家固定在GPU HBM中,其余专家映射至CXL-NDP。为应对NDP有限算力,引入上下文感知的混合精度量化,基于预填充阶段为每个专家分配1-4比特位宽。所提出的推理系统在跨设备间重叠计算,同时最小化跨设备数据移动。在GPU-NDP系统上的评估显示,该方法相较当前最优方案,解码吞吐最高提升8.7倍,平均准确率仅下降0.13%。

原文摘要 · Abstract (English)

Mixture-of-Experts (MoE) models scale large language models through conditional computation, but inference becomes memory-bound once expert weights exceed the capacity of GPU memory. In this case, weights must be offloaded to external memory, and fetching them incurs costly and repeated transfers. We address this by adopting CXL-attached near-data processing (CXL-NDP) as the offloading tier to execute cold experts in place, converting expensive parameter movement into cheaper activation movement. Unlike prior GPU-NDP systems that are largely context-agnostic and reactive, we develop a context-aware MoE system that uses prefill-stage activation statistics to guide decoding-stage expert placement, dynamically pins hot experts in GPU-side HBM, and maps the remainder to CXL-NDP. To meet NDP's limited compute throughput, we introduce context-aware mixed-precision quantization that allocates per-expert bitwidths (1-4 bit) based on prefill stage. The resulting MoE inference system overlaps GPU and NDP execution while minimizing cross-device movement. The evaluation on the GPU-NDP system shows that our approach achieves up to an 8.7-fold decoding throughput improvement over the state-of-the-art method, while incurring only a 0.13% average accuracy drop.

MoECXL推理优化近数据处理

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