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arXiv · 2505.18577

CXL Topology-Aware and Expander-Driven Prefetching: Unlocking SSD Performance

Dongsuk Oh·Miryeong Kwon·Jiseon Kim·Eunjee Na·Junseok Moon·Hyunkyu Choi·Seonghyeon Jang·Hanjin Choi·Hongjoo Jung·Sangwon Lee·Myoungsoo Jung
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Abstract

Integrating compute express link (CXL) with SSDs allows scalable access to large memory but has slower speeds than DRAMs. We present ExPAND, an expander-driven CXL prefetcher that offloads last-level cache (LLC) prefetching from host CPU to CXL-SSDs. ExPAND uses a heterogeneous prediction algorithm for prefetching and ensures data consistency with CXL.mem's back-invalidation. We examine prefetch timeliness for accurate latency estimation. ExPAND, being aware of CXL multi-tiered switching, provides end-to-end latency for each CXL-SSD and precise prefetch timeliness estimations. Our method reduces CXL-SSD reliance and enables direct host cache access for most data. ExPAND enhances graph application performance and SPEC CPU's performance by 9.0$\times$ and 14.7$\times$, respectively, surpassing CXL-SSD pools with diverse prefetching strategies.

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Dongsuk Oh, Miryeong Kwon, Jiseon Kim, Eunjee Na, Junseok Moon, Hyunkyu Choi, Seonghyeon Jang, Hanjin Choi, Hongjoo Jung, Sangwon Lee, Myoungsoo Jung. 2025-05-24. CXL Topology-Aware and Expander-Driven Prefetching: Unlocking SSD Performance. https://arxiv.org/abs/2505.18577

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