Towards Rack-as-a-Computer in Memory Interconnect Era with Coordinated Operating System Sharing
Yuxin Ren, Mingrui Liu, Hongbo Li, Chang Liao, Xiaojia Huang, Jianhua Zhang, Hanjun Guo, Yubo Liu, Ning Jia · 2025
Emerging memory interconnect (such as CXL and HCCS) promises rack-scale machine to become a reality, as the interconnect enables load/store accessible memory shared across the entire rack. However, the rack-scale shared memory poses two unique challenges on the operating system, primarily because of synchronization bottleneck and reliability issue. First, hardware cache coherence is not guaranteed, thus existing lock-based approach is ineffective to synchronize cross-node memory access. Second, memory faults significantly increase, and additional interconnect hops and switches expand fault surface and radius. As a result, current systems cannot efficiently leverage in-rack shared memory and instead manage rack resource in a disaggregated way, suffering from unnecessary networking/RDMA transmission overhead and redundant data copies.