Partial and Incremental Page Migration for Multi-host CXL Disaggregated Shared Memory

This technical report presents Partial and Incremental Page Migration (PIPM), a novel approach designed to enhance page migration efficiency in multi-host Compute Express Link (CXL) disaggregated shared memory (CXL-DSM) systems. Traditional page migration techniques, primarily developed for single-host environments, are shown to be inadequate for multi-host scenarios due to increased latency and coordination overhead. The report details how PIPM addresses these challenges through two main strategies: partial migration, which selectively migrates frequently accessed cache blocks to local memory while retaining less-frequently accessed blocks in CXL memory, and incremental migration, which allows for data movement without incurring additional transfer overheads. The architectural support for PIPM, including a majority-vote migration policy and a two-level remapping table, is also discussed. Evaluation results indicate that PIPM achieves significant performance improvements, with an average speedup of 1.86 times over existing methods, thereby optimizing data placement and enhancing overall system performance.