1. A method comprising: constructing a model to determine performance of each computing application of a plurality of computing applications based on allocation of resources to the computing applications, where how the allocation of the resources to the computing applications affects the performance is unknown beforehand; allocating the resources to the computing applications based at least on the model constructed, where the resources include at least one hardware resource; and, where the resources are overloaded as allocated to the computing applications, performing performance degradation of each computing application based at least on priorities of the computing applications relative to one another and on the model constructed, to reduce usage of the resources by the computing applications so that the resources are no longer overloaded, wherein how the priorities of the computing applications affect the performance degradation in a relative manner to one another is known and predictable beforehand.