1. A computer-readable, non-transitory medium storing therein a job scheduling program that causes a computer to execute a procedure, the procedure comprising: determining an assignment order, which is an order in which jobs of users are assigned to a computational resource, based upon priority levels of the users associated with the jobs; assigning the jobs to the computational resource based upon the assignment order; reducing a priority level of a user in response to a job of the user that has been assigned to the computational resource; and increasing the priority level of the user with time, wherein, in the assigning of the jobs, regarding the priority level of the user, if, at a future time, which is a fixed time period from start of execution of jobs of the user, an amount of an increase in the priority level of the user is expected to be equal to or larger than an amount of a reduction in the priority level of the user for another job, assignment of the another job of the user to the computational resource is executed.