2025/05/24 by Oh, Dongsuk, Kwon, Miryeong, Kim, Jiseon +8
#FOS: Computer and information sciences #Hardware Architecture (cs.AR)
paper · doi:10.48550/arxiv.2505.18577
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× and 14.7×, respectively, surpassing CXL-SSD pools with diverse prefetching strategies.