On Exploiting Page Sharing in a Virtualised Environment - An Empirical Study of Virtualization Versus Lightweight Containers

While virtualized solutions are firmly entrenched in cloud data centers to provide isolated execution environments, the chief overhead it suffers from is that of memory consumption. Even pages that are common in multiple virtual machines (VMs) on the same physical machine (PM) are not shared and multiple copies exist thereby draining valuable memory resources and capping the number of VMs that can be instantiated on a PM. Lightweight containers (LWCs) on the other hand does not suffer from this situation since virtually everything is shared via Copy on Write semantics. As a result the capacity of a PM to host LWCs is far higher than hosting equivalent VMs. In this paper, we evaluate a solution using uKSM to exploit memory page redundancy amongst multiple VMs on a PM executing the same operating system thereby enabling a comparison of the two technologies as far as its capacity to instantiate multiple instances is concerned. We performed a thorough empirical evaluation of the two solutions and present comprehensive results.