R&D: Oasis, Persistent Memory Oversubscription for Emerging Applications via Persistent MMAP

ACM Digital Library has published, in SYSTOR ’25: Proceedings of the 18th ACM International Systems and Storage Conference, an article written by Ziyi Zhao, and Scott Rixner, Rice University, Houston, Texas, USA.

Abstract: “Emerging Persistent Memory (PMEM) applications bypass the traditional I/O stack and access physical PMEM directly to achieve high performance. However, this access model often leads to poor resource utilization and limited scalability.“

“This paper presents Oasis, which virtualizes PMEM to provide the illusion of infinite-capacity PMEM, and enables PMEM oversubscription without requiring application changes. At the core of Oasis is a persistent mmap operation that maintains persistence and crash-consistency guarantees while automatically migrating data between PMEM and a backing store. This allows idle memory to be reclaimed for use by other applications. Oasis leverages mature memory management techniques, avoiding the need to reinvent core mechanisms while delivering strong performance benefits.“

“Oasis is evaluated within the Linux kernel across a broad range of workloads. Oasis improves system-wide performance by up to 1.7× by oversubscribing PMEM and enabling more applications to run concurrently. Under oversubscription, Oasis reduces physical PMEM usage by up to 80% with modest overhead. Even when PMEM is not oversubscribed, Oasis delivers up to 30% performance improvement due to more efficient resource management.“