The Department of Computer Science at the University of Cyprus cordially invites you to the Colloquium entitled:

Scheduling in Distributed Real-Time Systems Utilizing Imprecise Computations


Speaker: ProfProf. Eleni D. Karatza
Affiliation: Aristotle University of Thessaloniki, Greece
Category: Colloquium
Location: Room 148, Faculty of Pure and Applied Sciences (FST-01), 1 University Avenue, 2109 Nicosia, Cyprus (directions)
Date: Tuesday, May 12th, 2009
Time: 11:00-12:00 EET
Host: Marios Dikaiakos (mdd AT

Distributed real-time systems are very important in our daily life as most of today?s applications require high quality results within precise timing constraints. In real-time systems the correctness of the system does not depend only on the logical results of the computations, but also on the time at which the results are produced. That is, the jobs in a real-time system have deadlines which must be met. If a real-time job cannot meet its deadline, then its results will be useless, or even catastrophic. Therefore, a real-time system must guarantee that every job will complete its execution before its deadline. Moreover, it must tolerate possible software faults that may cause failures during the execution of a job. Consequently, the most important aspect of a distributed real-time system is the scheduling algorithm which decides the allocation of processors to jobs and also the order in which jobs will be executed on processors. One of the techniques that have been proposed by researchers for the scheduling of real-time jobs is called imprecise computations. This is the case where the execution of a real-time job is allowed to return intermediate (imprecise) results of poorer, but still acceptable quality, when the deadline of the job cannot be met. In a distributed real-time system, jobs usually consist of frequently communicating tasks which can be processed in parallel. An efficient way to schedule dynamic, parallel jobs is gang scheduling. With this technique, parallel job tasks are scheduled and executed simultaneously on different processors. Jobs of this type are called gangs. In this talk we present issues related to the performance of scheduling algorithms for gangs in distributed real-time systems, where transient software faults may cause failures during the execution of a job. Particularly, the imprecise computations technique is discussed and the advantages of incorporating this technique into the scheduling process are presented.

Short Bio:
Eleni D. Karatza is an Associate Professor in the Department of Informatics, at the Aristotle University of Thessaloniki, Greece. Her research interests include Computer Systems Modeling and Simulation, Performance Evaluation of Parallel and Distributed systems, Resource Allocation and Scheduling, Cluster Computing, Grid Computing and Resource Discovery in the Grid. Dr. Karatza has authored or co-authored over 130 technical papers and book chapters including two papers that earned best paper awards at the 39th Annual Simulation Symposium (ANSS 2006) and the 10th International Symposium on Performance Evaluation of Computer and Telecommunication Systems (SPECTS 2007) respectively. Dr. Karatza is Editor in Chief of Simulation Modelling Practice and Theory (Elsevier), Area Editor of the Journal of Systems and Software (Elsevier), Associate Editor of the International Journal of Communication Systems (Wiley), Associate Editor of the ACM Transactions on Modeling and Computer Simulation, Associate Editor of the International Journal of Simulation and Process Modelling (Inderscience Publishers), Editorial Board Member of the International Journal of Communication Networks and Distributed Systems (Inderscience Publishers), Editorial Board Member of the International Journal of Simulation: Systems, Science & Technology (The UK Simulation Society), Editorial Advisory Board Member in the Book Series: Emerging Communication and Service Technologies (Troubador Publishing Ltd) and Advisory Editorial Board Member of Simulation: Transactions of The Society for Modeling and Simulation International (Sage Publications). Dr. Karatza is a Senior member of the IEEE, and of the Society for Modeling and Simulation International (SCS).

  Mailing List:

Sponsor: The CS Colloquium Series is supported by a generous donation from Microsoft