This paper presents the development of a model and a control policy for the scheduling problem. To simplify the treatise, as anticipated, in the following only a single-processor case is taken into account; however, the considerations introduced herein hold also in the case of multi-core computing systems. The scheduling problem is entirely treated using the class of discrete-time dynamic systems as the main modelling instrument. The general model obtained can be seen as a switching system; however, simplifying the model and representing only the necessary involved quantities, allows to exploit even simpler modelling frameworks like the one of linear time-invariant systems. This is herein used to develop an entirely new scheduler. The devised scheduler is implemented on a microcontroller kernel, and some benchmark are shown to validate the design approach. Also, the problem is considered of providing the scheduler with a configuration interface that is `friendly' for the typical system administrator, who in general has little (if any) knowledge of the control theory.

Chapter Contents:

• 5.1 Modelling
• 5.1.1 The core phenomenon
• 5.2 Control synthesis
• 5.2.1 Inner loop
• 5.2.2 Outer loop
• 5.2.3 Complexity comparison with existing policies
• 5.2.4 Simulation example
• 5.3 Set point generation for (soft) real-time systems
• 5.3.1 Overload detection and rescaling
• 5.3.2 Reinitialisation and feedforward
• 5.4 Experimental results and comparisons
• 5.4.1 MiBench benchmark
• 5.4.2 Hartstone benchmark
• 5.4.3 Extended Hartstone benchmark
• 5.4.4 Summary of results
• 5.5 Set point generation for general purpose systems
• 5.5.1 Tasks with periodic deadlines
• 5.5.2 Tasks with a single deadline
• 5.5.3 Tasks without deadlines
• 5.5.4 Event-triggered tasks
• 5.5.5 Parameter setting
• 5.5.6 Simulation examples
• 5.5.7 Concluding remarks

Inspec keywords: scheduling; multiprocessing systems; discrete time systems; microcontrollers

Other keywords: scheduling problem; switching system; discrete-time dynamic system; linear time-invariant system; multicore computing system; microcontroller kernel; system administrator; configuration interface; control theory

Subjects: Microprocessor chips; Operating systems; Multiprocessing systems