1. A method comprising: constructing a respective model to determine respective 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 respective performances is unknown before the respective performances occur; allocating, by a processor of a computing device, the resources to the computing applications based at least on the respective models constructed, where the resources include at least one hardware resource; and, where the resources are overloaded as allocated to the computing applications, performing, by the processor of the computing device, performance degradation of each computing application based at least on priorities of the computing applications relative to one another and on the respective models 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 with respect to how much the respective performances of the computing applications degrade, before the performance degradation occurs, wherein constructing the respective model to determine the respective performance of each computing application comprises, for a given computing application, determining a modeling function receiving as input the allocation of the resources to the given computing application and providing as output the respective performance of the given computing application for the allocation of the resources.