The present disclosure is directed to dynamically prioritizing, selecting or ordering a plurality threads for execution by processor circuitry based on a quality of service and/or class of service value/indicia assigned to the thread by an operating system executed by the processor circuitry. As threads are executed by processor circuitry, the operating system dynamically updates/associates respective class of service data with each of the plurality of threads. The current quality of service/class of service data assigned to the thread by the operating system is stored in a manufacturer specific register (MSR) associated with the respective thread. Selection circuitry polls the MSRs on a periodic, aperiodic, intermittent, continuous, or event-driven basis and determines an execution sequence based on the current class of service value associated with each of the plurality of threads.