Real-rate scheduling

Traditionally, real-time scheduling mechanisms have been used to provide predictable scheduling latency but these mechanisms are difficult to use in general-purpose operating systems (OSs) because they require precise specification of thread requirements in terms of low-level resources such as CPU cycles. In a general-purpose environment such a specification may not be statically available. In this paper, we present the design, implementation and evaluation of a novel feedback-based real-rate scheduler that automatically infers thread requirements and thus makes it easier to use real-time scheduling mechanisms in general-purpose OSs. The real-rate controller uses thread-specified time-stamps that indicate a thread´s progress to estimate resource requirements. The goal of the controller is to regulate the overallocation of resources and the delay experienced by a thread. It meets these goals by using gain compensation and by choosing an appropriate sampling period for the controller that depends only on the granularity of thread time-stamps. A key benefit of the real-rate approach is that it can be easily applied in a general-purpose environment across different applications because the controller does not require any tuning.