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Algorithms and Complexity Concerning the Preemptive Scheduling of Periodic, RealTime Tasks on One Processor
 RealTime Systems
, 1990
"... We investigate the preemptive scheduling of periodic, realtime task systems on one processor. First, we show that when all parameters to the system are integers, we may assume without loss of generality that all preemptions occur at integer time values. We then assume, for the remainder of the pape ..."
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Cited by 242 (15 self)
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We investigate the preemptive scheduling of periodic, realtime task systems on one processor. First, we show that when all parameters to the system are integers, we may assume without loss of generality that all preemptions occur at integer time values. We then assume, for the remainder of the paper, that all parameters are indeed integers. We then give as our main lemma both necessary and sufficient conditions for a task system to be feasible on one processor. Although these conditions cannot, in general, be tested efficiently (unless P = NP), they do allow us to give efficient algorithms for deciding feasibility on one processor for certain types of periodic task systems. For example, we give a pseudopolynomial time algorithm for synchronous systems whose densities are bounded by a fixed constant less than 1. This algorithm represents an exponential improvement over the previous best algorithm. We also give a polynomialtime algorithm for systems having a fixed number of distinct typ...
Feasibility Problems for Recurring Tasks on One Processor
, 1992
"... We give a comprehensive summary of our recent research on the feasibility problems for various types of hardrealtime preemptive task systems on one processor. We include results on periodic, sporadic, and hybrid task systems. While many of the results herein have appeared elsewhere, this is the fi ..."
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Cited by 58 (10 self)
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We give a comprehensive summary of our recent research on the feasibility problems for various types of hardrealtime preemptive task systems on one processor. We include results on periodic, sporadic, and hybrid task systems. While many of the results herein have appeared elsewhere, this is the first paper presenting a holistic view of the entire problem.
Efficient Design, Analysis, and Implementation of Complex Multiprocessor RealTime Systems
, 2013
"... The advent of multicore technologies is a fundamental development that is impacting software design processes across a wide range of application domains, including an important category of such applications, namely, those that have realtime constraints. This development has led to much recent work ..."
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Cited by 1 (0 self)
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The advent of multicore technologies is a fundamental development that is impacting software design processes across a wide range of application domains, including an important category of such applications, namely, those that have realtime constraints. This development has led to much recent work on multicoreoriented resource management frameworks for realtime applications. Unfortunately, most of this work focuses on simple task models where complex but practical runtime behaviors among tasks do not arise. In practice, however, many factors such as programming methodologies, interactions with external devices, and resource sharing often result in complex runtime behaviors that can negatively impact timing correctness. The goal of this dissertation is to support such more realistic and complex applications in multicorebased realtime systems. The thesis of this dissertation is: Capacity loss (i.e., over provisioning) can be significantly reduced on multiprocessors while providing soft and hard realtime guarantees for realtime applications that exhibit complex runtime behaviors such as selfsuspensions, graphbased precedence constraints, nonpreemptive sections, and parallel execution segments by designing new realtime scheduling algorithms and developing new schedulability tests.
Generation and Comparison of ConstraintBased Heuristics Using the Structure of Constraints
, 1997
"... The central topic of this thesis is the conception and deployment of a framework in which heuristics for combinatorial problems, especially for Constraint Satisfaction Problems (CSPs), can be developed and compared relative to the time effort for finding solutions. Our study of heuristics shows how ..."
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The central topic of this thesis is the conception and deployment of a framework in which heuristics for combinatorial problems, especially for Constraint Satisfaction Problems (CSPs), can be developed and compared relative to the time effort for finding solutions. Our study of heuristics shows how to use the properties of constraints to guarantee a better worstcase performance of the solution algorithms. The common framework is based on special constraints, namely the proposed subquadrangles. We demonstrate that every constraint can be represented by intersections and unions of subquadrangles. The developed framework connects three aspects of heuristic search: relaxation, reduction, and decomposition. Firstly, we show that the property of subquadrangles allows us to control the search with respect to causality. Secondly, subquadrangles can be reduced to simpler subquadrangles, and hence, a given problem to simpler problems. Thirdly, by using the variables on which the subquadrangles...