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: (A) upon causing the physical CPU, in which processing of the virtual computer is in a running state, to execute the overhead processing, measure a run time used by the physical CPU to execute the overhead processing, and manage a cumulative run time, which is an accumulation of the run time, for each of the physical CPUs; and (B) upon causing the overhead processing to be executed subsequent to the (A), select a physical CPU in which the cumulative run time is smallest as the physical CPU to execute the overhead processing.