14,202 research outputs found
Combined Scheduling of Time-Triggered Plans and Priority Scheduled Task Sets
© Owner/Author (2016). This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in ACM SIGAda Ada Letters, 36(1), 68-76, http://dx.doi.org/10.1145/10.1145/2971571.2971580.[EN] Preemptive, priority-based scheduling on the one hand, and time-triggered scheduling on the other, are the two
major techniques in use for development of real-time and embedded software. Both have their advantages and
drawbacks with respect to the other, and are commonly adopted in mutual exclusion.
In a previous paper, we proposed a software architecture that enables the combined and controlled execution of
time-triggered plans and priority-scheduled tasks. The goal was to take advantage of the best of both approaches by
providing deterministic, jitter-controlled execution of time-triggered tasks (e.g., control tasks), coexisting with a set
of priority-scheduled tasks, with less demanding jitter requirements.
In this paper, we briefly describe the approach, in which the time-triggered plan is executed at the highest priority
level, controlled by scheduling decisions taken only at particular points in time, signalled by recurrent timing events.
The rest of priority levels are used by a set of concurrent tasks scheduled by static or dynamic priorities. We also
discuss several open issues such as schedulability analysis, use of the approach in multiprocessor architectures,
usability in mixed-criticality systems and needed changes to make this approach Ravenscar compliant.This work has been partly supported by the Spanish Governmentâs project M2C2 (TIN2014-56158-C4-1-P-AR) and the European
Commissionâs project EMC2 (ARTEMIS-JU Call 2013 AIPP-5, Contract 621429).Real SĂĄez, JV.; SĂĄez Barona, S.; Crespo Lorente, A. (2016). Combined Scheduling of Time-Triggered Plans and Priority Scheduled Task Sets. Ada Letters. 36(1):68-76. https://doi.org/10.1145/2971571.2971580S6876361T. P. Baker and A. Shaw. The cyclic executive model and Ada. In Proceedings IEEE Real Time Systems Symposium 1988, Huntsville, Alabama, pages 120--129, 1988.P. Balbastre, I. Ripoll, J. Vidal, and A. Crespo. A Task Model to Reduce Control Delays. Real-Time Systems, 27(3):215--236, September 2004.A. Burns and R. Davis. Mixed Criticality Systems - A Review. Technical report, Depatment of Computer Science, University of York, 2013.A. Cervin. Integrated Control and Real-Time Scheduling. PhD thesis, Lund Institute of Technology, April 2003.R. Dobrin. Combining Offline Schedule Construction and Fixed Priority Scheduling in Real-Time Computer Systems. PhD thesis, Mälardalen University, 2005.S. Hong, X. Hu, and M. Lemmon. Reducing Delay Jitter of Real-Time Control Tasks through Adaptive Deadline Adjustments. In IEEE Computer Society, editor, 22nd Euromicro Conference on Real-Time Systems -- ECRTS, pages 229--238, 2010.J. W. S. Liu. Real-Time Systems. Prentice-Hall Inc., 2000.J. Palencia and M. González-Harbour. Schedulability Analysis for Tasks with Static and Dynamic Offsets. In 9th IEEE Real-Time Systems Symposium, 1998.M. J. Pont. The Engineering of Reliable Embedded Systems: LPC1769 edition. Number ISBN: 978-0-9930355-0-0. SafeTTy Systems Limited, 2014.J. Real and A. Crespo. Incorporating Operating Modes to an Ada Real-Time Framework. Ada Letters, 30(1):73--85, April 2010.J. Real, S. Sáez, and A. Crespo. Combining time-triggered plans with priority scheduled task sets. In M. Bertogna and L. M. Pinho, editors, Reliable Software Technologies -- Ada-Europe 2016, volume 9695 of Lecture Notes in Computer Science. Springer, June 2016.S. Sáez, J. Real, and A. Crespo. An integrated framework for multiprocessor, multimoded real-time applications. In M. Brorsson and L. Pinho, editors, Reliable Software Technologies -- Ada-Europe 2012, volume 7308, pages 18--34. Springer-Verlag, June 2012.S. Sáez, J. Real, and A. Crespo. Implementation of Timing-Event Anities in Ada/Linux. Ada Letters, 35(1), April 2015.A. J. Wellings and A. Burns. A Framework for Real-Time Utilities for Ada 2005. Ada Letters, XXVII(2), August 2007
Analysis and Optimization of Mixed-Criticality Applications on Partitioned Distributed Architectures
A Comprehensive Experimental Comparison of Event Driven and Multi-Threaded Sensor Node Operating Systems
The capabilities of a sensor network are strongly influenced by the operating system used on the sensor nodes. In general, two different sensor network operating system types are currently considered: event driven and multi-threaded. It is commonly assumed that event driven operating systems are more suited to sensor networks as they use less memory and processing resources. However, if factors other than resource usage are considered important, a multi-threaded system might be preferred. This paper compares the resource needs of multi-threaded and event driven sensor network operating systems. The resources considered are memory usage and power consumption. Additionally, the event handling capabilities of event driven and multi-threaded operating systems are analyzed and compared. The results presented in this paper show that for a number of application areas a thread-based sensor network operating system is feasible and preferable
Scheduling policies and system software architectures for mixed-criticality computing
Mixed-criticality model of computation is being increasingly
adopted in timing-sensitive systems. The model not only
ensures that the most critical tasks in a system never fails,
but also aims for better systems resource utilization in normal condition. In this report, we describe the widely used
mixed-criticality task model and fixed-priority scheduling
algorithms for the model in uniprocessors. Because of the
necessity by the mixed-criticality task model and scheduling
policies, isolation, both temporal and spatial, among tasks is
one of the main requirements from the system design point
of view. Different virtualization techniques have been used
to design system software architecture with the goal of isolation. We discuss such a few system software architectures
which are being and can be used for mixed-criticality model
of computation
CSP channels for CAN-bus connected embedded control systems
Closed loop control system typically contains multitude of sensors and actuators operated simultaneously. So they are parallel and distributed in its essence. But when mapping this parallelism to software, lot of obstacles concerning multithreading communication and synchronization issues arise. To overcome this problem, the CT kernel/library based on CSP algebra has been developed. This project (TES.5410) is about developing communication extension to the CT library to make it applicable in distributed systems. Since the library is tailored for control systems, properties and requirements of control systems are taken into special consideration. Applicability of existing middleware solutions is examined. A comparison of applicable fieldbus protocols is done in order to determine most suitable ones and CAN fieldbus is chosen to be first fieldbus used. Brief overview of CSP and existing CSP based libraries is given. Middleware architecture is proposed along with few novel ideas
- âŠ