192 research outputs found
Predictability of Fixed-Job Priority Schedulers on Heterogeneous Multiprocessor Real-Time Systems
The multiprocessor Fixed-Job Priority (FJP) scheduling of real-time systems
is studied. An important property for the schedulability analysis, the
predictability (regardless to the execution times), is studied for
heterogeneous multiprocessor platforms. Our main contribution is to show that
any FJP schedulers are predictable on unrelated platforms. A convenient
consequence is the fact that any FJP schedulers are predictable on uniform
multiprocessors
On the periodic behavior of real-time schedulers on identical multiprocessor platforms
This paper is proposing a general periodicity result concerning any
deterministic and memoryless scheduling algorithm (including
non-work-conserving algorithms), for any context, on identical multiprocessor
platforms. By context we mean the hardware architecture (uniprocessor,
multicore), as well as task constraints like critical sections, precedence
constraints, self-suspension, etc. Since the result is based only on the
releases and deadlines, it is independent from any other parameter. Note that
we do not claim that the given interval is minimal, but it is an upper bound
for any cycle of any feasible schedule provided by any deterministic and
memoryless scheduler
On the complexity of optimal priority assignment for periodic tasks upon identical processors
International audienceIn this paper we study global fixed-priority scheduling of periodic task systems upon identical multiprocessor platforms. Based on existing feasibility tests for periodic task systems upon identical multiprocessor platforms, we show (using a dummy priority assignment algorithm) that optimal priority assignment for these systems exists. Then we provide an algorithm based on RMUS[m/(3m-2)] that has lower complexity. Finally, we conjuncture that, contrary to the general opinion, (pseudo-) polynomial optimal priority assignment algorithms for periodic task systems upon identical processors might exist
Preliminary results for introducing dependent random variables in stochastic feasibility analysis on CAN
International audienceWe consider periodic and sporadic messages that are scheduled on a Controller Area Network (CAN) bus. We propose a stochastic analysis framework that provides probability distributions of message response times where the arrival of messages are given by independent random variables. This analysis can be extended easily to the case of dependent random variables. We also define the necessary steps to validate such analysis
Proceedings of Junior Researcher Workshop on Real-Time Computing
It is our great pleasure to welcome you to Junior Researcher Workshop on Real-Time Computing 2007, which is held conjointly with the 15th conference on Real-Time and Network Systems (RTNS'07). The first successful edition was held conjointly with the French Summer School on Real-Time Systems 2005 (http://etr05.loria.fr). Its main purpose is to bring together junior researchers (Ph.D. students, postdoc, ...) working on real-time systems. This workshop is a good opportunity to present our works and share ideas with other junior researchers and not only, since we will present our work to the audience of the main conference. In response to the call for papers, 14 papers were submitted and the international Program Committee provided detailed comments to improve these work-in-progress papers. We hope that our remarks will help the authors to submit improved long versions of theirs papers to the next edition of RTNS. JRWRTC'07 would not be possible without the generous contribution of many volunteers and institutions which supported RTNS'07. First, we would like to express our sincere gratitude to our sponsors for their financial support : Conseil Général de Meuthe et Moselle, Conseil Régional de Lorraine, Communauté Urbaine du Grand Nancy, Université Henri Poincaré, Institut National Polytechnique de Lorraine and LORIA and INRIA Lorraine. We are thankful to Pascal Mary for authorizing us to use his nice picture of “place Stanislas” for the proceedings and web site (many others are available at www.laplusbelleplacedumonde.com). Finally, we are most grateful to the local organizing committee that helped to organize the conference
A Survey of Probabilistic Timing Analysis Techniques for Real-Time Systems
This survey covers probabilistic timing analysis techniques for real-time systems. It reviews and critiques the key results in the field from its origins in 2000 to the latest research published up to the end of August 2018. The survey provides a taxonomy of the different methods used, and a classification of existing research. A detailed review is provided covering the main subject areas: static probabilistic timing analysis, measurement-based probabilistic timing analysis, and hybrid methods. In addition, research on supporting mechanisms and techniques, case studies, and evaluations is also reviewed. The survey concludes by identifying open issues, key challenges and possible directions for future research
A framework for the response time analysis of fixed-priority tasks with stochastic inter-arrival times
Real-time scheduling usually considers worst-case values for the
parameters of task (or message stream) sets, in order to provide
safe schedulability tests for hard real-time systems. However,
worst-case conditions introduce a level of pessimism that is often
inadequate for a certain class of (soft) real-time systems. In this
paper we provide an approach for computing the stochastic
response time of tasks where tasks have inter-arrival times
described by discrete probabilistic distribution functions, instead
of minimum inter-arrival (MIT) values
Non-preemptive scheduling algorithms and schedulability conditions for real-time systems with precedence and latency constraints
First we justify our concern in latency constraints for real-time systems with precedence constraints. We evoke the model based on graph theory used to state and solve the problem of non-preemptive scheduling systems with precedence and latency constraints. Because latency constraints involve pairs of operations related to the graph which models the precedence constraints, we define three relations between pairs of operations, relations which determine the way of scheduling the operations. We give a necessary and sufficient condition of schedulability for the particular case of systems with precedence and latency constraints, where all pairs, on which latency constraints are imposed, are in one of these relations. Finally, we give a general schedulability condition for real-time systems with precedence and latency contraints and we propose a scheduling algorithm which is proved optimal
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