An Efficient Online Benefit-aware Multiprocessor Scheduling Technique for Soft Real-Time Tasks Using Online Choice of Approximation Algorithms

Maximizing the benefit gained by soft real-time tasks in many applications and embedded systems is highly needed to provide an acceptable QoS (Quality of Service). Examples of such applications and embedded systems include real-time medical monitoring systems, video- streaming servers, multiplayer video games, and mobile multimedia devices. In these systems, tasks are not equally critical (or beneficial). Each task comes with its own benefit-density function which can be different from the others’. The sooner a task completes, the more benefit it gains. In this work, a novel online benefit-aware preemptive approach is presented in order to enhance scheduling of soft real-time aperiodic and periodic tasks in multiprocessor systems. The objective of this work is enhancing the QoS by increasing the total benefit, while reducing flow times and deadline misses. This method prioritizes the tasks using their benefit-density functions, which imply their importance to the system, and schedules them in a real-time basis. The first model I propose is for scheduling soft real-time aperiodic tasks. An online choice of two approximation algorithms, greedy and load-balancing, is used in order to distribute the low- priority tasks among identical processors at the time of their arrival without using any statistics. The results of theoretical analysis and simulation experiments show that this method is able to maximize the gained benefit and decrease the computational complexity (compared to existing algorithms) while minimizing makespan with fewer missed deadlines and more balanced usage of processors. I also propose two more versions of this algorithm for scheduling SRT periodic tasks, with implicit and non-implicit deadlines, in addition to another version with a modified loadbalancing factor. The extensive simulation experiments and empirical comparison of these algorithms with the state of the art, using different utilization levels and various benefit density functions show that these new techniques outperform the existing ones. A general framework for benefit-aware multiprocessor scheduling in applications with periodic, aperiodic or mixed real-time tasks is also provided in this work.Computer Science, Department o

Proceedings Work-In-Progress Session of the 14th Real-Time and Embedded Technology and Applications Symposium, 22-24 April, 2008 St. Louis, USA

The Work-In-Progress session of the 14th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS \u2708) presents papers describing contributions both to state of the art and state of the practice in the broad field of real-time and embedded systems. The 25 accepted papers were selected from 27 submissions. This proceedings is also available as University of Nebraska–Lincoln Technical Report TR-UNL-CSE-2008-0003, at http://lakota.unl.edu/facdb/csefacdb/TechReportArchive/TR-UNL-CSE-2008-0003.pdf Special thanks go to the General Chairs – Scott Brandt and Frank Mueller and Program Chairs – Chenyang Lu and Christopher Gill for their support and guidance. Special thanks also go to the Work-In-Progress Program Committee Members – Zonghua Gu, Kyoung-Don Kang, Xue Liu and Shangping Ren for their hard work in reviewing papers. Ying Lu Work-In-Progress Chair, 14th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS\u2708) Table of Contents L. Yao, F. Gao, X. Cui, G. Yu, C. Shang, Two-Level Priority Real-Time Scheduling Strategy for Node System in Wireless Sensor Network. 1 Y. Yu, S. Ren, Similarities between Timing Constraint Sets: Towards Interchangeable Constraint Models for Real-World Software Systems. 5 F. Muhammad, B. M. Khurram, F. Muller, C. Belleudy, M. Auguin, Precognitive DVFS: Minimizing Switching Points to Further Reduce the Energy Consumption. 9 R. J. Bril, P. J.L. Cuijpers, Towards Exploiting the Preservation Strategy of Deferrable Servers. 13 D. Zhu, A. Ș. Tosun, Adaptive Path Scheduling for Mobile Element to Prolong the Lifetime of Wireless Sensor Networks. 17 D. Luong, J. S. Deogun, S. Goddard, Feedback Scheduling of Real-Time Divisible Loads in Clusters. 21 J. S. Deogun, S. Goddard, Developing New Models to Reason about Time and Space. 25 D. Zöbel, A Compositional Transformation to Bridge the Gap between the Technical System and the Computational System. 29 C. Bartolini, E. Bini, G. Lipari, Slack-based Sensitivity Analysis for EDF. 33 A. M. Picu, A. Fraboulet, E. Fleury, On Frequency Optimization for Power Saving in WSNs. 37 R. Staudinger, Towards Automatic Translation to Temporally Predictable Code. 41 L. Qiu, N. Chen, S. Ren, Checkpointing Implementation for Real-time and Fault Tolerant Applications on RTAI. 45 A. Loos, D. Fey, A 2000 Frames / s Programmable Binary Image Processor Chip for Real Time Machine Vision Applications. 49 G. Modena, L. Abeni, L. Palopoli, Providing QoS by Scheduling Interrupt Threads. 53 A. Anta, P. Tabuada, On the Benefits of Relaxing the Periodicity Assumption for Control Tasks. 57 J. Shamsi, M. Brockmeyer, Mapping Overlay Networks for Real-Time Applications. 61 J. Sztipanovits, G. Karsai, S. Neema, H. Nine, J. Porter, R. Thibodeaux, P. Völgyesi, Towards a Model-based Toolchain for the High-Confidence Design of Embedded Systems. 65 H. Aysan, S. Punnekkat, R. Dobrin, Adding the Time Dimension to Majority Voting Strategies. 69 W. Wiles, G. Quan, An Experimental Model for the Verification of Dynamic Voltage-Scaling Scheduling Techniques on Embedded Systems. 73 T. H. Feng, E. A. Lee, H. D. Patel, J. Zou, Toward an Effective Execution Policy for Distributed Real-Time Embedded Systems. 77 J. Yi, C. Poellabauer, X. S. Hu, D. Rajan, L. Zhang, Cooperative Network and Energy Management for Reservation-based Wireless Real-Time Environments. 81 B. Sanati, A. M. K. Cheng, Maximizing Job Benefits on Multiprocessor Systems Using a Greedy Algorithm. 85 C. Belwal, A. M. K. Cheng, W. Taha, A. Zhu, Timing Analysis of the Priority based FRP System. 89 A. Giani, G. Karsai, T. Roosta, A. Shah, B. Sinopoli, J. Wiley, A Testbed for Secure and Robust SCADA Systems. 93 M. Wilson, R. Cytron, J. Turner, Partial Program Admission by Path Enumeration. 9