Patent ID: 8291413

Claim:
A virtual computer system, comprising: hardware including a CPU; and a virtual machine manager configured to virtualize the hardware to construct a plurality of virtual machines and to manage the plurality of virtual machines such that the plurality of virtual machines execute a plurality of guest OSes, wherein the virtual machine manager includes: a detector configured to detect a change in an operating frequency of the CPU; a scheduler configured to manage a schedule for allocating the CPU to the plurality of guest OSes in a time-sharing manner, the scheduler being configured such that if the detector detects a change in the operating frequency and the operating frequency decreases below a predetermined prescribed frequency, the scheduler increases a time for which the CPU is to be allocated to one or more predetermined particular quest OSes of the plurality of guest OSes; and a dispatcher configured to allocate the CPU to the plurality of guest OSes in a time-sharing manner according to the schedule managed by the scheduler; wherein: the scheduler is configured to increase the time for which the CPU is to be allocated to the one or more particular guest OSes so that the CPU is allocated to the one or more particular guest OSes for a time required to maintain an absolute throughput corresponding to a processing capability of the CPU required by the one or more particular guest OSes to operate at the prescribed frequency, and the scheduler is configured such that when the prescribed frequency is defined as Fs, the operating frequency is defined as Fc, and the absolute throughput is defined as Rs, the scheduler determines a time corresponding to a throughput indicated by â€œRsÃ—(Fs/Fc)â€ to be the time required to maintain the absolute throughput.