Task scheduling is one of the key mechanisms to ensure timeliness in embedded real-time systems. Such systems have often the need to execute not only application tasks but also some urgent routines (e.g. error-detection actions, consistency checkers, interrupt handlers) with minimum latency. Although fixed-priority schedulers such as Rate-Monotonic (RM) are in line with this need, they usually ...

Among packet-scheduling disciplines for providing end-toend Quality-of-Service (QoS) guarantees to different applications, including real-time services, two classes of algorithms have received particular attention: those based on Generalized Processor Sharing (GPS) and those based on Earliest Deadline First (EDF). One reason for the popularity of GPS-based schemes is that their powerful propert...

This paper describes an algorithm, called Dynamic Window-Constrained Scheduling (DWCS), designed to meet the service constraints on packets from multiple, network-bound media streams with different performance objectives. Using only two attributes, a deadline and a loss-tolerance per packet stream, DWCS: (1) can limit the number of late packets over finite numbers of consecutive packets in loss...

This paper introduces an analytical method for approximating the performance of a two-class priority M/M/1 system. The system is fully non-preemptive. More specifically, the prioritized class-1 jobs are real-time and served with the non-preemptive earliest-deadline-first (EDF) policy, but despite their priority cannot preempt any non real-time class-2 job. The waiting class-2 jobs can only be s...

Real-time applications are performance critical applications that require bounded service latency. In multi-hop wireless ad-hoc and sensor networks, communication delays are dominant over processing delays. Therefore, to enable real-time applications in such networks, the communication latency must be bounded. In this paper, we derive expressions of realtime capacity that characterize the abili...

A typical characteristic of real-time systems is concurrent processing of tasks under strict timing requirements. These timing requirements may impose not only direct constraints, such as deadlines, but also indirect timing constraints in terms of inter–task dependencies. However, scheduling policies which can deal with some of these constraints effectively are limited, especially for the on-li...

We present our approach to real-time service-oriented scheduling problems with the objective of maximizing the total system utility. Different from the traditional utility accrual scheduling problems that each task is associated with only a single time utility function (TUF), we associate two different TUFs—a profit TUF and a penalty TUF—with each task, tomodel the real-time services that not o...

Task execution Deadline Time (DL) in real-time systems is a critical constraint. Every task should have a Maximum Computational Time (MCT) that is needed before reaching a given DL time. Scheduling jobs in real-time systems is thus a nondeterministic polynomial NP problem. Three algorithms can be found in literature to solve these problems in a multi processor environment; are the Earliest Dead...