This paper proposes an analysis method to check the schedulability of a set of sporadic tasks under earliest deadline first (EDF) scheduler. The sporadic task model consists of subtasks with precedence constraints, arbitrary arrival times and deadlines. In order to determine the schedulability, we present an approach to find exact worst case response time (WCRT) of subtatsks. With the technique...

We consider a set of real-time periodic tasks where some tasks are preferably executed as soon as possible (ASAP) and others as late as possible (ALAP) while still meeting their deadlines. After introducing the idea of preference-oriented (PO) execution, we formally define the concept of PO-optimality. For fully-loaded systems (with 100% utilization), we first propose a PO-optimal scheduler, na...

für meinen Vater ii Summary Within this thesis time evaluated predicate/transition nets (t-pr/t-nets) have been developed for the purpose to model, simulate and verify complex real-time systems. Therefore, t-pr/t-nets integrate concepts to model timing constraints and can be analysed by the means of structural analysis such as the calculation of sand t-invariants as well as the identification o...

In the studies of real-time concurrency control protocols (RT-CCPs), it is always assumed that earliest deadline first (EDF) is employed as the CPU scheduling algorithm. However, using purely (ultimate) deadline for priority assignment may not be suitable for distributed real-time database systems (DRTDBS) in which there exist different kinds of transactions, such as global and local transactio...

Partitioned scheduling algorithms are typically based on Earliest Deadline First (EDF) or Rate-Monotonic Scheduling (RMS). Often, heuristics like First Fit are applied for task allocation to processors. The performance of the heuristics can be improved by sorting tasks in a preprocessing step. While for partitioned EDF, Decreasing Utilization is the approved sequence, there is a variety of sort...

In this paper we examine the packets’ delay performance under the temporal fairness opportunistic scheduling (TFOS) algorithm which is first introduced in [1]. We also simulate the earliest deadline-first (EDF) scheduling algorithm in the wireless environment. We find that the opportunistic scheduling algorithm biases the users who always experience the good channel condition in packets’ delay ...

The conflict resolution technique normally used in Real Time Systems is EDF(Earliest Deadline First). However ,this technique is found to be biased towards the shorter transactions. No technique has been Reported in the literature to remove this biasing. This paper presents a new technique of dynamic priority assignment in real time transactions that is based on the ratio of time left to the ti...

Highly dynamic programming environments for embedded real-time systems require a strict isolation of real-time threads from each other to achieve dependable systems. We propose a new real-time scheduling technique, called guaranteed percentage (GP) scheme that assigns each thread a specific percentage of the processor power. A hardware scheduler in conjunction with a multithreaded processor gua...

We address the problem of combining the collective hard real-time resource requirements into a single hard real-time resource requirement supporting composability. We first propose a resource model to characterize a periodic resource allocation and present exact schedulability conditions for our proposed resource model under the EDF (earliest deadline first) and RM (rate monotonic) algorithms. ...

Recent trends toward multi-core architectures in real-time embedded systems pose challenges in designing efficient real-time multiprocessor scheduling algorithms. We believe that it is important to take into consideration both timing constraints of tasks (urgency) and parallelism restrictions of multiprocessor platforms (parallelism) together when designing scheduling algorithms. Motivated by t...