Abstract

Most priority-based schedulers lack the ability to control the relative execution rates of applications. A recent scheme, called lottery scheduling [WW94], uses randomization to control the execution rates of threads in proportion to the tickets allocated to them. However, randomization does not afford sufficient control over short periods of time; e.g., it would fail to provide the intended execution rates for threads that run for less than 10 timeslices. This paper presents a new scheme that controls execution rates over much smaller intervals and provides better service guarantees. Simulation results prove its advantage over lottery scheduling. The scheme is based on charging threads for CPU usage and occasionally skipping some threads to keep the usage close to the intended proportion. Unlike earlier charge-based schemes, which adjust the priorities of running threads, this scheme schedules threads in round-robin order. Despite its improved quality of service, the scheduler process...

Citations