Support for Hierarchical Scheduling in FreeRTOS

This paper presents the implementation of a HierarchicalScheduling Framework (HSF) on an open sourcereal-time operating system (FreeRTOS) to support the temporalisolation between a number of applications, on a single processor.The goal is to achieve predictable integration and reusability ofindependently developed components or applications. We presentthe initial results of the HSF implementation by running it onan AVR 32-bit board EVK1100. The paper addresses the fixed-priority preemptive schedulingat both global and local scheduling levels. It describes the detaileddesign of HSF with the emphasis of doing minimal changes tothe underlying FreeRTOS kernel and keeping its API intact.Finally it provides (and compares) the results for the performancemeasures of idling and deferrable servers with respect to theoverhead of the implementation.Submitted to 16th IEEE International Conference on Emerging Technologies and Factory automation (ETFA'11) ©2011 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE."