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October 16th 2003
Computer Laboratory > Research > Systems Research Group > NetOS > Seminars > October 16th 2003

Xen and the Art of Virtualisation

Keir Fraser
Numerous systems have been designed which use virtualisation 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. In this talk I present 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 idealised 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 virtualisation 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 unvirtualised case. We considerably outperform competing commercial and freely available solutions in a range of microbenchmarks and system-wide tests.