1. A computer comprising: a plurality of physical CPUs; a plurality of virtual computers which are configured to execute predetermined processing and to which one of the plurality of physical CPUs is assigned; and a virtual computer control component configured to manage the plurality of virtual computers, the virtual computer control component being able to cause the plurality of physical CPUs to execute overhead processing which is required by the plurality of virtual computers, wherein the virtual computer control component is configured to: manage the overhead processing by associating the overhead processing with identification information indicating whether the overhead processing is processing that is requested in continuation during processing of the virtual computer, or processing that is not requested in continuation; and (A) upon causing a physical CPU to execute the overhead processing, measure a run time used by the physical CPU to execute the overhead processing; (B) manage a cumulative run time for each of the physical CPUs, wherein a cumulative run time of a physical CPU is an accumulation of the run time on that physical CPU; (C) upon causing the overhead processing to be executed, when the identification information associated with the overhead processing indicates that the overhead processing is processing that is requested in continuation during processing of the virtual computer, select a physical CPU which is not executing processing of the virtual computer in which the cumulative run time is smallest as the physical CPU to execute the overhead processing; and (D) upon causing the overhead processing to be executed, when the identification information associated with the overhead processing indicates that the overhead processing is processing that is not requested in continuation during processing of the virtual computer, select a physical CPU which is executing processing of the virtual computer that has requested the overhead processing as the physical CPU to execute the overhead processing.