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Unformatted text preview: Pre-Virtualization: Slashing the Cost of Virtualization Joshua LeVasseur Volkmar Uhlig Matthew Chapman Peter Chubb Ben Leslie Gernot Heiser University of Karlsruhe, Germany IBM T. J. Watson Research Center, New York National ICT Australia University of New South Wales, Australia Abstract Despite its current popularity, para-virtualization has an enormous cost. Its diversion from the platform architecture abandons many of the benefits that come with pure virtu- alization (the faithful emulation of the platform API): sta- ble and well-defined platform interfaces, single binaries for kernel and device drivers (and thus lower testing, mainte- nance, and support cost), and vendor independence. These limitations are accepted as inevitable for significantly bet- ter performance and the ability to provide virtualization-like behavior on non-virtualizable hardware, such as x86. We argue that the above limitations are not inevitable, and present pre-virtualization , which preserves the bene- fits of full virtualization without sacrificing the performance benefits of para-virtualization. In a semi-automatic step an OS is prepared for virtualization. The required mod- ifications are orders of magnitudes smaller than for para- virtualization. A virtualization module, that is collocated with the guest OS, transforms the standard platform API into the respective hypervisor API. The guest OS is still programmed against a common architecture, and the bi- nary remains fully functional on bare hardware. The sup- port of a new hypervisor or updated interface only requires the implementation of a single interface mapping. We val- idated our approach for a variety of hypervisors, on two very different hardware platforms (x86 and Itanium), with multiple generations of Linux as guests. We found that pre- virtualization achieves essentially the same performance as para-virtualization, at a fraction of the engineering cost. 1. INTRODUCTION Virtual machines, originally introduced in the 70s , have recently gained immense popularity. The reason is National ICT Australia is funded by the Australian Gov- ernments Backing Australias Ability initiative, in part through the Australian Research Council. Technical Report 2005-30, November 2005, Fakultat fur Informatik, Uni- versitat Karlsruhe (TH) that they provide an attractive approach to solving a vari- ety of problems arising in a number of quite dissimilar con- texts. These include server consolidation [2, 31], migration of users complete operating environments between physi- cal machines [9,26], intrusion detection , debugging , secure computing platforms with strictly controlled infor- mation ow [4, 7, 20, 25], co-existence of realtime and non- realtime applications , and backward compatibility with older or out-of-production hardware....
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- Spring '12