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Schedulability analysis for real-time systems has been the subject of prominent research over the past several decades. One of the key foundations of schedulability analysis is an accurate worst case execution time (WCET) measurement for each task. In real-time systems that support preemption, the cache related preemption delay (CRPD) can represent a significant component (up to 44% as documented...
To move mixed criticality research into industrial practice requires models whose run-time behaviour is acceptable to systems engineers. Certain aspects of current models, such as abandoning lower criticality tasks when certain situations arise, do not give the robustness required in application domains such as the automotive and aerospace industries. In this paper a new bailout protocol is developed...
We focus on the problem of computing tight deadline miss models for real-time systems, which bound the number of potential deadline misses in a given sequence of activations of a task. In practical applications, such guarantees are often sufficient because many systems are in fact not hard real-time. Our major contribution is a general formulation of that problem in the context of systems where some...
Multi-core platforms represent the answer of the industry to the increasing demand for computational capabilities. From a real-time perspective, however, the inherent sharing of resources, such as memory subsystem and I/O channels, creates inter-core timing interference among critical tasks and applications deployed on different cores. As a result, modular per-core certification cannot be performed,...
The Quasi-Partitioning Scheduling algorithm optimally solves the problem of scheduling a feasible set of independent implicit-deadline sporadic tasks on a symmetric multiprocessor. It iteratively combines bin-packing solutions to determine a feasible task-to-processor allocation, splitting task loads as needed along the way so that the excess computation on one processor is assigned to a paired processor...
Recent developments in embedded hardware have empowered human experiences through pervasive computing. While embedded systems are becoming more powerful, they still fall short when faced with users' growing desire for running more resource-demanding applications. To bridge this gap, one solution is to leverage powerful resources residing at remote sites by performing computation offloading. Unfortunately,...
The sporadic DAG task model exposes parallelism that may exist within individual tasks to the run-time scheduling mechanism, and is therefore considered a particularly suitable model for representing recurrent real-time tasks that are to be implemented upon multiprocessor platforms. This paper proposes and evaluates an extension to the model to allow for the concurrent modeling of conditional execution...
Engine control applications include software tasks that are triggered at predetermined angular values of the crankshaft, thus generating a computational workload that varies with the engine speed. To avoid overloads at high rotation speeds, these tasks are implemented to self adapt and reduce their computational demand by switching mode at given rotation speeds. For this reason, they are referred...
Mixed-criticality real-time scheduling has been developed to improve resource utilization while guaranteeing safe execution of critical applications. These studies use optimistic resource reservation for all the applications to improve utilization, but prioritize critical applications when the reservations become insufficient at runtime. Many of them however share an impractical assumption that all...
Historically safety-critical real-time systems have been implemented using a cyclic executive (CE). Here a series of frames (minor cycles) are executed in sequence. Once the series is complete the sequence is repeated. The duration of the full sequence is often known as the major cycle. Within each frame, units of computation (jobs) are executed, again in sequence. Although there are a number of drawbacks...
When multiple computational resource elements collaborate to handle events in a cyber-physical system, scheduling algorithms on these resource elements and the communication delay between them contribute to the overall system utilization and schedulability. Employing earliest deadline first (EDF) scheduling in real-time cyber-physical systems has many challenges. First, the network layer of a resource...
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