Real-time software engineering in Ada: observations and recommendations

Fixed priority scheduling periodic tasks with varying execution priority

“…This process continues until all deadlines of first jobs have been checked. Thus conditions (1) and (2) are sufficient for all subtask deadlines to be met.…”

Rate Monotonic Analysis for Real-Time Systems

“…In addition, we have addressed the associated hardware scheduling support [10] [22], implications for Ada scheduling rules [5], algorithm implementation in an Ada runtime system [1], and schedulability analysis of input/output paradigms [7]. Finally, we also have performed a number of design and analysis experiments to test the viability of the theory [2,13].…”

“…In this vein, the concurrency architecture of a generic avionics system [131 was designed using the principles of rate monotonic theory. Additionally, an inertial navigation system simulator written at the SEI [1] Is an example of an existing system that was subjected to rate monotonic analysis and Improved as a consequence.…”

“…A schedulability model is basically a set of rate monotonic Inequalities (i.e., the extended schedulability test) that captures the schedulability-related characteristics of a set of tasks. As described in [1], there is generally one inequality for each task. Each Inequality has terms that describe or model various factors that affect the ability of a task to meet its deadline.…”

An Analysis of Input/Output Paradigms for Real-Time Systems

“…As described in [1], when a process preempts a lower priority process, the execution state of the lower priority process is saved and the execution state of the higher priority process is established. When the higher priority process completes its processing and relinquishes the CPU to a lower priority process, its execution state is saved and the state of the lower priority process is reestablished.…”