Beyond the limitations of real-time scheduling theory: a unified scheduling theory for the analysis of real-time systems

We investigate the mathematical properties of event bound functions as they are used in the worst-case response time analysis and utilization tests. We figure out the differences and similarities between the two approaches. Based on this analysis, we derive a more general form do describe events and event bounds. This new unified approach gives clear new insights in the investigation of real-time systems, simplifies the models and will support algebraic proofs in future work. In the end, we present a unified analysis which allows the algebraic definition of any scheduler. Introducing such functions to the real-time scheduling theory will lead two a more systematic way to integrate new concepts and applications to the theory. Last but not least, we show how the response time analysis in dynamic scheduling can be improved.

Excluding Parallel Execution to Improve Global Fixed Priority Response Time Analysis

Response Time Analysis (RTA) is an effective method for testing the schedulability of real-time tasks on multiprocessor platforms. Existing RTAs for global fixed priority scheduling calculate the upper bound of the worst case response time of each task. Given a target task, existing RTAs first calculate the workload upper bound of each higher priority task (than the target task), and then calculate the interference on the target task by each higher priority task according to the obtained workload upper bounds. The workload of a task consists of three parts: carry-in, body and carry-out. The interference from all these three parts may be overestimated in existing RTAs. However, although the overestimation of the interference from body is the major factor that causes the low accuracy of existing RTAs, all existing work only focuses on how to reduce the overestimation of the interference from carry-in, and there is no method to reduce the overestimation of the interference from body or carry-out. In this work, we propose a method to calculate the lower bound of the accumulative time in which the target task and higher priority tasks are executed in parallel. By excluding the parallel execution time from the interference, we derive a new RTA test that can reduce the overestimation of the interference from all three parts of the workload. Extensive experiments are conducted to verify the superior performance of the proposed RTA test.

Evaluation of Fire Disaster Emergency Response Capacity using Open-source Data and Response Time Analysis in Ilorin Metropolis

This study evaluates the response capacity to fire disaster emergency response system in Ilorin metropolis using Open-source data and response time analysis. Road and street information were obtained from Geofabrik. In addition, coordinates of fire service stations and fire disaster risk spots, specifically fuel and gas stations were acquired using Garmin 76X handheld GPS. Using the relationship of the length of road segments and speed, the travel time was computed in ArcGIS 10.4 environment. With the Network analyst tool, the response capability of the fire stations was evaluated at different response times (1, 2, and 3 minutes) based on service area coverage. The results showed that the fire stations could only cover 0.24%, 0.68%, and 1.22% of the service area within 1-, 2- and 3-minute response time, respectively, whereas 97.86% of the metropolis requires longer time (>3 minutes). Finding from this study has revealed the inadequacy of the existing fire disaster emergency response system to effectively cover the city. This will be useful for local and state governments in policy directives on strengthening fire disaster emergency response structure.