Real-Rate Scheduling

• Venue: RTAS '04 Proceedings of the 10th IEEE Real-Time and Embedded Technology and Applications Symposium
• Year: 2004

Traditionally, real-time scheduling mechanismshave been used to provide predictable scheduling latency butthese mechanisms are difficult to use in general-purpose operatingsystems (OSs) because they require precise specification ofthread requirements in terms of low-level resources such as CPUcycles. In a general-purpose environment such a specificationmay not be statically available. In this paper, we present thedesign, implementation and evaluation of a novel feedback-basedreal-rate scheduler that automatically infers thread requirementsand thus makes it easier to use real-time scheduling mechanismsin general-purpose OSs. The real-rate controller uses thread-specifiedtime-stamps that indicate a threadýs progress to estimateresource requirements. The goal of the controller is to regulatethe overallocation of resources and the delay experienced by athread. It meets these goals by using gain compensation and bychoosing an appropriate sampling period for the controller thatdepends only on the granularity of thread time-stamps. A keybenefit of the real-rate approach is that it can be easily appliedin a general-purpose environment across different applicationsbecause the controller does not require any tuning.