Scheduling Theory Research Papers - Academia.edu (original) (raw)

From its roots in job-shop scheduling, research into fixed priority pre-emptive scheduling theory has progressed from the artificial constraints and simplistic assumptions used in early work to a sufficient level of maturity that it is... more

From its roots in job-shop scheduling, research into fixed priority pre-emptive scheduling theory has progressed from the artificial constraints and simplistic assumptions used in early work to a sufficient level of maturity that it is being increasingly used in the implementation of real-time systems. It is therefore appropriate that within this special issue we provide an historical perspective on the development of fixed priority pre-emptive scheduling.

This paper surveys single-project, single-objective, deterministic project scheduling problems in which activities can be processed using a finite or infinite (and uncountable) number of modes concerning resources of various categories... more

This paper surveys single-project, single-objective, deterministic project scheduling problems in which activities can be processed using a finite or infinite (and uncountable) number of modes concerning resources of various categories and types. The survey is based on a unified framework of a project scheduling model including resources, activities, objectives, and schedules. Most important models and solution approaches across the class

10th International Conference on Real-Time and Embedded Computing Systems and Applications (RTCSA), Göteborg, Sweden, August 2004. ... The Jitter Margin and Its Application in the Design of Real-Time ... Anton Cervin,1 Bo Lincoln,2 Johan... more

10th International Conference on Real-Time and Embedded Computing Systems and Applications (RTCSA), Göteborg, Sweden, August 2004. ... The Jitter Margin and Its Application in the Design of Real-Time ... Anton Cervin,1 Bo Lincoln,2 Johan Eker,3 Karl-Erik Årzén,4 Giorgio ...

In this paper, we exend timed automata with asynchronous processes i.e. tasks triggered by events as a model for real-time systems. The model is expressive enough to describe concurrency and synchronization, and real time tasks which may... more

In this paper, we exend timed automata with asynchronous processes i.e. tasks triggered by events as a model for real-time systems. The model is expressive enough to describe concurrency and synchronization, and real time tasks which may be periodic, sporadic, preemptive or non-preemptive. We generalize the classic notion of schedulability to timed automata. An automaton is schedulable if there exists a scheduling strategy such that all possible sequences of events accepted by the automaton are schedulable in the sense that all associated tasks can be computed within their deadlines. We believe that the model may serve as a bridge between scheduling theory and automata-theoretic approaches to system modeling and analysis. Our main result is that the schedulability checking problem is decidable. To our knowledge, this is the first general decidability result on dense-time models for real time scheduling without assuming that preemptions occur only at integer time points. The proof is based on a decidable class of updatable automata: timed automata with subtraction in which clocks may be updated by subtractions within a bounded zone. The crucial observation is that the schedulability checking problem can be encoded as a reachability problem for such automata. Based on the proof, we have developed a symbolic technique and a prototype tool for schedulability analysis.

Many safety-critical embedded systems are subject to certification requirements; some systems may be required to meet multiple sets of certification requirements, from different certification authorities. Certification requirements in... more

Many safety-critical embedded systems are subject to certification requirements; some systems may be required to meet multiple sets of certification requirements, from different certification authorities. Certification requirements in such "mixed-criticality” systems give rise to interesting scheduling problems, that cannot be satisfactorily addressed using techniques from conventional scheduling theory. In this paper, we study a formal model for representing such mixed-criticality workloads. We demonstrate first the intractability of determining whether a system specified in this model can be scheduled to meet all its certification requirements, even for systems subject to merely two sets of certification requirements. Then we quantify, via the metric of processor speedup factor, the effectiveness of two techniques, reservation-based scheduling and priority-based scheduling, that are widely used in scheduling such mixed-criticality systems, showing that the latter of the two is superior to the former. We also show that the speedup factors we obtain are tight for these two techniques.

The controller synthesis paradigm provides a general framework for scheduling real-time applications. Schedulers can be considered as controllers of the applications; they restrict their behavior so that given scheduling requirements are... more

The controller synthesis paradigm provides a general framework for scheduling real-time applications. Schedulers can be considered as controllers of the applications; they restrict their behavior so that given scheduling requirements are met. We study a modeling methodology based on the controller synthesis paradigm. The methodology allows to get a correctly scheduled system from timed models of its processes in an incremental manner, by application of composability results which simplify schedulability analysis. It consists in restricting successively the system to be scheduled by application of constraints defined from scheduling requirements. The latter are a conjunction of schedulability requirements that express timing properties of the processes and policy requirements about resource management. The presented methodology allows a unified view of scheduling theory and approaches based on timing analysis of models of real-time applications.

Backpropagation is a supervised learning procedure for a class of artificial neural networks which has recently been widely used in training such neural networks to perform relatively nontrivial tasks like text-to-speech conversion or... more

Backpropagation is a supervised learning procedure for a class of artificial neural networks which has recently been widely used in training such neural networks to perform relatively nontrivial tasks like text-to-speech conversion or autonomous land vehicle control. However, the slow rate of convergence of the backpropagation algorithm has limited its application to rather small networks and various researchers have implemented parallel versions on a number of different parallel platforms. This work presents experimental speed-up performance results from a parallel implementation of the backpropagation learning algorithm on an Intel iPSC/2 hypercube parallel processor, for such well-known neural nets like NETTalk and extrapolated speed-up results for large scale hypercube systems from analytic performance models of the implementation.

This article deals with real-time critical systems modelling and verification. Real-time scheduling theory provides algebraic methods and algorithms in order to make timing constraints verifications of these systems. Nevertheless, many... more

This article deals with real-time critical systems modelling and verification. Real-time scheduling theory provides algebraic methods and algorithms in order to make timing constraints verifications of these systems. Nevertheless, many industrial projects do not perform analysis with real-time scheduling theory even if demand for use of this theory is large and the industrial application field is wide (avionics, aerospace, automotive, autonomous systems, …). The Cheddar project investigates why real-time scheduling theory is not used and how its usability can be increased. The project was launched at the University of Brest in 2002. In Lecture Notes on Computer Sciences, vol. 5026, pp. 240–253, 2008, we have presented a short overview of this project. This article is an extended presentation of the Cheddar project, its contributions and also its ongoing works.

We consider the job-shop problem with sequence-dependent setup times. We focus on the formal definition of schedule generation schemes (SGSs) based on the semi-active, active, and non-delay schedule categories. We study dominance... more

We consider the job-shop problem with sequence-dependent setup times. We focus on the formal definition of schedule generation schemes (SGSs) based on the semi-active, active, and non-delay schedule categories. We study dominance properties of the sets of schedules obtainable with each SGS. We show how the proposed SGSs can be used within single-pass and multi-pass priority rule based heuristics. We study several priority rules for the problem and provide a comparative computational analysis of the different SGSs on sets of instances taken from the literature. The proposed SGSs significantly improve previously best-known results on a set of hard benchmark instances.

This paper extends the applications of scheduling theory to certain problems in the area of finance. Specifically, a branch and bound algorithm to identify optimal repayment policies for multiple loans (credit purchases) has been... more

This paper extends the applications of scheduling theory to certain problems in the area of finance. Specifically, a branch and bound algorithm to identify optimal repayment policies for multiple loans (credit purchases) has been developed. Each loan qualifies for ...

Tasks' scheduling has always been a central problem in the embedded real-time systems community. As in general the scheduling problem is NP-hard, researchers have been looking for efficient heuristics to solve the scheduling problem in... more

Tasks' scheduling has always been a central problem in the embedded real-time systems community. As in general the scheduling problem is NP-hard, researchers have been looking for efficient heuristics to solve the scheduling problem in polynomial time. One of the most important scheduling strategies is the Earliest Deadline First (EDF). It is known that EDF is optimal for uniprocessor platforms for many cases, such as: non-preemptive synchronous tasks(i.e., all tasks have the same starting time and cannot be interrupted), and preemptive asynchronous tasks (i.e., the tasks may be interrupted and may have arbitrary starting time). However, Mok showed that EDF is not optimal in multiprocessor platforms. In fact, for the multiprocessor platforms, the scheduling problem is NP-complete in most of the cases where the corresponding scheduling problem can be solved by a polynomial-time algorithm for uniprocessor platforms. Coffman and Graham identified a class of tasks for which the scheduling problem can be solved by a polynomial time algorithm, that is, two-processor platform, no resources, arbitrary partial order relations, and every task is nonpreemptive and has a unit computation time. Our paper introduces a new non-trivial and practical subclass of tasks, called urgent tasks. Briefly, a task is urgent if it is executed right after it is ready or it can only wait one unit time after it is ready. Practical examples of embedded real time systems dealing with urgent tasks are all modern building alarm systems, as these include urgent tasks such as `checking for intruders', `sending a warning signal to the security office',`informing the building's owner about a potential intrusion', and so on. By using propositional logic, we prove a new result in schedulability theory, namely that the scheduling problem for asynchronous and preemptive urgent tasks can be solved in polynomial time.