Chrono: Meticulous Hotness Measurement and Flexible Page Migration for Memory Tiering

As the memory demand continues to surge, the limitations of DRAM scalability have spurred the development of various new memory technologies in today's data centers. In order to harness the benefits of the heterogeneous memory architecture, tiering has become a widely adopted memory management paradigm. The effectiveness of a tiered memory management system primarily relies on its ability to accurately identify frequently accessed ("hot") pages and infrequently accessed ("cold") pages, and efficiently relocate them between tiers. However, existing systems rely on coarse-grained frequency measurement schemes that do not align with the performance characteristics of modern memory devices and memory-intensive applications. Additionally, these systems often incorporate rigid rules or manually configured parameters for page classification, resulting in inflexible migration strategies.