Memory buddies

TLDR

Content‑based page sharing consolidates identical memory pages across virtual machines, but in multi‑server data centers this benefit is limited because identical pages on different hosts cannot be shared. The authors seek to identify VM placement strategies that co‑locate VMs with similar memory content to fully exploit page sharing.

Abstract

Many data center virtualization solutions, such as VMware ESX, employ content-based page sharing to consolidate the resources of multiple servers. Page sharing identifies virtual machine memory pages with identical content and consolidates them into a single shared page. This technique, implemented at the host level, applies only between VMs placed on a given physical host. In a multi-server data center, opportunities for sharing may be lost because the VMs holding identical pages are resident on different hosts. In order to obtain the full benefit of content-based page sharing it is necessary to place virtual machines such that VMs with similar memory content are located on the same hosts.