Xen and the art of virtualization

TLDR

Virtualization is used to partition computer resources, but existing solutions often require specialized hardware, lack commodity OS support, aim for 100 % binary compatibility at the cost of performance, or trade security and functionality for speed. This paper introduces Xen, an x86 virtual machine monitor that enables multiple commodity operating systems to share conventional hardware safely and resource‑managed, without sacrificing performance or functionality. Xen achieves this by providing an idealized virtual‑machine abstraction that allows OSes such as Linux, BSD, and Windows XP to be ported with minimal effort, targeting support for up to 100 VMs on a modern server. Xen delivers negligible performance overhead—only a few percent relative to the unvirtualized case—and outperforms competing commercial and free solutions in microbenchmarks and system‑wide tests.

Abstract

Numerous systems have been designed which use virtualization to subdivide the ample resources of a modern computer. Some require specialized hardware, or cannot support commodity operating systems. Some target 100% binary compatibility at the expense of performance. Others sacrifice security or functionality for speed. Few offer resource isolation or performance guarantees; most provide only best-effort provisioning, risking denial of service.This paper presents Xen, an x86 virtual machine monitor which allows multiple commodity operating systems to share conventional hardware in a safe and resource managed fashion, but without sacrificing either performance or functionality. This is achieved by providing an idealized virtual machine abstraction to which operating systems such as Linux, BSD and Windows XP, can be ported with minimal effort.Our design is targeted at hosting up to 100 virtual machine instances simultaneously on a modern server. The virtualization approach taken by Xen is extremely efficient: we allow operating systems such as Linux and Windows XP to be hosted simultaneously for a negligible performance overhead --- at most a few percent compared with the unvirtualized case. We considerably outperform competing commercial and freely available solutions in a range of microbenchmarks and system-wide tests.