Traditional Virtual Machine Monitor (VMM) virtualizes some devices and instructions, which induces performance overhead to guest operating systems. Furthermore, the virtualization contributes a large amount of codes to VMM, which makes a VMM prone to bugs and vulnerabilities. On the other hand, in cloud computing, cloud service provider configures virtual machines based on requirements which are specified by customers in advance. As resources in a multi-core server increase to more than

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... in the future, virtualization is not necessary although it provides convenience for cloud computing. Based on the above observations, this paper presents an alternative way for constructing a VMM: configuring a booting interface instead of virtualization technology. A lightweight virtual machine monitor -OSV is proposed based on this idea. OSV can host multiple full functional Linux kernels with little performance overhead. There are only 6 hyper-calls in OSV. The Linux running on top of OSV is intercepted only for the inter-processor interrupts. The resource isolation is implemented with hardware-assist virtualization. The resource sharing is controlled by distributed protocols embedded in current operating systems. We implement a prototype of OSV on AMD Opteron processor based 32-core servers with SVM and cache-coherent NUMA architectures. OSV can host up to 8 Linux kernels on the server with less than 10 lines of code modifications to Linux kernel. OSV has about 8000 lines of code which can be easily tuned and debugged. The experiment results show that OSV VMM has 23.7% performance improvement compared with Xen VMM.