Ingens: Huge Page Support for the OS and Hypervisor

Memory capacity and demand have grown hand in hand in recent years. However, overheads for memory virtualization, in particular for address translation, grow with memory capacity as well, motivating hardware manufacturers to provide TLBs with thousands of entries for larger pages, or huge pages. Current OSes and hypervisors support huge pages with a hodge-podge of best-effort algorithms and spot fixes that make less and less sense as architectural support for huge pages matures. The time has come for a more fundamental redesign. Ingens is a framework for providing transparent huge page support in a coordinated way. Ingens manages contiguity as a first-class resource, and tracks utilization and access frequency of memory pages, enabling it to eliminate pathologies that plague current systems. Experiments with a Linux/KVM-based prototype show improved fairness and performance, and reduced tail latency and memory bloat for important applications such as Web services and Redis. We report early experiences with our in-progress port of Ingens to the ESX Hypervisor.