Time measurements within a virtual machine can sometimes be inaccurate due to difficulties with the guest operating system keeping the exact time.
Because virtual machines work by time-sharing host physical hardware, virtual machines cannot exactly duplicate the timing activity of physical machines. Virtual machines use several techniques to minimize and conceal differences in timing performance. However, the differences can still sometimes cause timekeeping inaccuracies and other problems in software running in a virtual machine.
Several things can be done to reduce the problem of timing inaccuracies: