Implementation of virtual time system for the distributed virtual machine monitor

In virtualization environment, time system is also a vital part of the whole system just as that in real computing environment. The system of distributed virtual machine monitor (DVMM) is designed to hide the lower distributed hardware resources with the virtualization technology and provide the feature of single system image (SSI) for the upper guest operating system (GOS) and applications. For the DVMM, we design and implement a virtual time system including four parts - keeping of physical time sources, the virtualization of time sources and timer interrupts, and the time synchronization in the VMM layer. This virtual time system not only correctly provides the complete time services for the GOS and user applications, but also properly manages the internal timekeeping to help the DVMM run on multi-machines and provide the feature of SSI to the upper software. With the technology of hardware assisted virtualization, this new virtual time system runs in the VMM layer instead of in user mode. By running the GOS and applications, we verify the functions of this virtual time system.