VMem: Enabling Application Management of Physical Memory Resources

Computing trends are leading high performance and enterprise platforms to adopt memory systems with increasingly complex architectures. As a result, many high end systems now include multiple types of memory with different capabilities and performance or distributed memory resources connected via a fast interconnect. New data management strategies are needed to exploit the unique advantages of these diverse and distributed architectures. As the primary generators of memory accesses, applications are well-suited to guide and tailor memory management for optimizing usage of these architectures. However, conventional data management in the operating system often proceeds with little knowledge of application intents or behaviors. This semantic gap limits optimization opportunities and can lead to inefficient utilization of complex memory resources. To address these challenges, this work proposes VMem: an application runtime and programming interface for enabling direct application control of physical memory resources. Designed and developed in Linux, VMem leverages standard Linux features and system calls to delegate key physical memory management tasks, including the allocation and recycling of physical memory, to the application itself. VMem does not require custom kernel code or non-standard hardware, and through integration with the memory allocator, can be deployed for use with many applications without needing to update or recompile application source. Experiments with the SPEC^® CPU 2017 benchmarks, this work demonstrate that many applications can use VMem to exert control over physical memory resources with little or no overhead compared to the default software stack. Additionally, this work discusses opportunities to improve memory utilization with VMem and demonstrate this potential by using it to implement an optimization that uses page replication to reduce costs associated with data migration.