No abstract

No 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.

Abstract. In this paper, we introduce a framework for providing incentives for honest participation in global-scale distributed trust management infrastructures. Our system can improve the quality of information supplied by these systems by reducing free-riding and encouraging honesty. Our approach is twofold: (1) we provide rewards for participants that advertise their experiences to others, and (2) impose the credible threat of halting the rewards, for a substantial amount of time, for participants who consistently provide suspicious feedback. For this purpose we develop an honesty metric which can indicate the accuracy of feedback.

ABSTRACT"Audio location" is a technique for accurate 3D location sensing using off-the-shelf audio hardware. The use of such hardware allows an audio location deployment to be lowcost and simple, as compared to other centimetre-scale location sensing systems. Another advantage of audio location is the ability to locate sounds that the user can make themselves, e.g. finger clicking, rather than requiring them to carry a locatable electronic "tag."