Scheduling Tool and Algorithm for Integrated Modular Avionics Systems

As computer and software technologies have advanced, the approach of Integrated Modular Avionics (IMA) has emerged in the field of avionics systems. The IMA approach can dramatically reduce production and maintenance costs and increase reliability of these safety-critical real time systems. The IMA hardware and foundation software must be able to provide guarantees to the application software so that the real-time constraints of all applications are simultaneously satisfied. In addition, each application must be protected from interference by other applications and the operating system software must itself be protected while physically sharing resources such as processors and communication hardware and busses. In other words, an IMA implementation requires that the concepts of spatial and temporal partitioning are provided and guaranteed. This paper introduces a scheduling tool and its algorithms that can be used to solve the fundamental temporal partitioning problems together with implementation related practical constraints. Based on the two-level scheduling hierarchy architecture of ARINC IMA standards, we model an IMA system composed of multiple partition servers and channel servers. A partition server models a protected application that may be composed of multiple concurrent tasks. A channel server provides temporally and spatially protected message transmission among applications. The ultimate objective of the tool is to provide schedules for both tasks and messages that provide for robust temporal partitioning.