An Empirical Study of Memory Sharing in Virtual Machines

Content-based page sharing is a technique often used in virtualized environments to reduce server memory requirements. Many systems have been proposed to capture the benefits of page sharing. However, there have been few analyses of page sharing in general, both considering its real-world utility and typical sources of sharing potential. The authors provide insight into this issue through an exploration and analysis of memory traces captured from real user machines and controlled virtual machines. They observe that absolute sharing levels (excluding zero pages) generally remain under 15%, contrasting with prior work that has often reported savings of 30% or more.