A system is set forth that includes a processor, one or more memory storage units, and software code stored in the one or more memory storage units. The software code is executable by the processor to generate a plurality of adaptive partitions that are each associated with one or more process threads. Each of the plurality of adaptive partitions has one or more corresponding scheduling attributes that are assigned to it. The software code further includes a scheduling system that is executable by the processor for selectively allocating the processor to run the process threads based on a comparison between ordering function values for each adaptive partition. The ordering function value for each adaptive partition is calculated using one or more of the scheduling attributes of the corresponding adaptive partition. The scheduling attributes that may be used to calculate the ordering function value include, for example, 1) the process budget, such as a guaranteed time budget, of the adaptive partition, 2) the critical budget, if any, of the adaptive partition, 3) the rate at which the process threads of an adaptive partition consume processor time, or the like. For each adaptive partition that is associated with a critical thread, a critical ordering function value also may be calculated. The scheduling system may compare the ordering function value with the critical ordering function value of the adaptive partition to determine the proper manner of billing the adaptive partition for the processor allocation used to run its associated critical threads. Methods of implementing various aspects of such a system are also set forth.