RapidSwap - a Hierarchical Far Memory.

As more and more memory-intensive applications are moved into the cloud, data center operators face the challenge of providing sufficient main memory resources while achieving high resource utilization. Solutions to overcome the unsatisfying performance degradation of traditional on-demand paging include memory disaggregation that allows applications to access remote memory or compressing memory pages in local DRAM; however, the former's extended failure domain and the latter's low efficacy limit their broad applicability. This paper presents RapidSwap, a hierarchical far memory manager that exploits the wide availability of phase-change memory (Intel Optane memory) in data centers to achieve quasi-DRAM performance at a significantly lower total cost of ownership (TCO). RapidSwap migrates infrequently accessed data to slower and cheaper devices in a hierarchy of storage devices by tracking applications' memory accesses. Evaluated with several real-world cloud benchmarks, RapidSwap achieves a reduction of 20% in operating cost at minimal performance degradation and is 30% more cost-effective than pure DRAM solutions. The results demonstrate that proper management of new memory technologies can yield significant TCO savings in cloud data centers.