1 / 13

Real-Time Scheduling [ Chapter 5.5]

Real-Time Scheduling [ Chapter 5.5]. Niranjan Rao Julapelly. Topics of Discussion. Real-time Computing Synchronous Programming Languages Real-time Operating Systems Real-time System Types Real-time System Methodologies Real-time Scheduling Algorithms

lcruz
Download Presentation

Real-Time Scheduling [ Chapter 5.5]

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Real-Time Scheduling[Chapter 5.5] Niranjan Rao Julapelly

  2. Topics of Discussion • Real-time Computing • Synchronous Programming Languages • Real-time Operating Systems • Real-time System Types • Real-time System Methodologies • Real-time Scheduling Algorithms • Real-time Scheduling Implementation Issues

  3. Real –time Computing • Software & hardware for systems which have real-time constraints and are interrupted often. • Comprises of: • Synchronous Programming Language. • Real-time Operating System. • Real-time Design Methodologies. Synchronous Programming Language • Provides abstract modules for scheduling algorithms, parallelism, pre-emption. • Finite state (execution time predictable), deterministic, synchronous dataflow. • Declarative and Imperative Languages. • Examples: Lustre, Quartz, SOL, Esterel.

  4. Real-Time Operating System (RTOS) • Examples: Embedded Systems (Appliance Controller, Spacecraft, Robots, Industrial Control. Early Real-time Systems • “Control Program” – American Airlines, IBM – Later called “Sabre Airline Reservation System”. Recent Important Real-time Systems • DSOS (Deep Six OS) – Geophysical Services Division, Texas Instruments. • Ptolemy Project, University of California, Berkeley [8]. • MARS (MAintainable Real-time System). • ARTS Kernel. • Spring Kernel. • CHAOS Kernel. • Alpha Kernel . • Dragon Kernel.

  5. Hard Real Time vs. Soft Real Time [McObject, 2006] • Critical real-time systems such as nuclear power plants or fly-by-wire airplanes are Hard Real Time • Non-critical real time systems where missed transactions only degrade system quality are Soft Real Time • Firm real-time systems are similar to soft real-time, except late tasks are discarded. • Scheduling algorithm depends on real time system characteristics

  6. Hard deadline

  7. Soft deadline

  8. Real-time System Design Methodologies • MASCOT (Modular Approach to Software Construction Operation and Test) • - Architecture Oriented (RT Control & interface definition between concurrent processes) • - British ground-air missile system. • HOOD (Hierarchic Object-Oriented Design) • - Hierarchical decomposition. • - European Space Agency – Aerospace project. • AADL (Architecture Analysis and Design Language) [6] - Automotive, aerospace industry. • RTSJ (Real-Time Specification for Java) [7]

  9. Real-time Scheduling Algorithms [Stankovic,’88] • Classification • Static vs Dynamic • Preemptive vs Non-preemptive • Global vs Local • Examples • Static: • - Fixed-priority Rate-monotonic algorithm • - Fixed-priority Deadline-monotonic algorithm • - Graph based Approach • Dynamic: • - Earliest Deadline First • - Least Laxity

  10. Real-time Implementation issues in Distributed Systems [Kasavant, ‘88] • Communication Delay - worst case execution time, non-deterministic • RPC - Remote blocking

  11. RT Research Groups • RT computing lab: http://www.eecs.umich.edu/RTCL/ • RT computation and communication group:http://www.cs.bu.edu/groups/realtime/ • RT and embedded systems laboratory:http://www.cs.virginia.edu/~control/ • Supercomputing and Parallel computing research group: http://www.cs.cmu.edu/~scandal/research-groups.html • Systems Research group: http://www.cc.gatech.edu/systems/ • Distributed systems research group: http://www-dsg.stanford.edu/ • Institute for systems engineering, RT Systems group: http://www.rts.uni-hannover.de/index.php/Main_Page/index.htm • Institute for computer engineering, RT Systems group: http://www.vmars.tuwien.ac.at/ RT Technical Commitees • IEEE Technical Committee on Real-Time Systems:http://cs-www.bu.edu/pub/ieee-rts/ • Euromicro Technical Committee on Real-time Systems: http://www.ecrts.org

  12. RT Scientific conferences

  13. References http://en.wikipedia.org/wiki/Real-time_operating_system S. Cheng, J.A. Stankovic and K. Ramamritham, ‘‘Scheduling Algorithms for Hard Real-Time Systems: A Brief Survey’’, pp. 150-173 in Hard Real-Time Systems: Tutorial, IEEE (1988). T. L. Casavant and J. G. Kuhl, ‘‘A Taxonomy of Scheduling in General Purpose Distributed Computing Systems’’, IEEE Transactions on Software Engineering 14(2), pp. 141-154 (February 1988). A. Burns, ‘‘Scheduling Hard Real-Time Systems: A Review’’, Software Engineering Journal 6(3), pp. 116-128 (1991). K. Ramamritham and J.A. Stankovic, ‘‘Dynamic Task Scheduling in Hard Real-Time Distributed Systems’’, IEEE Software 1(3), pp. 65-75 (July 1984). McObject LLC, “Real-time Databases for Embedded Systems”, Precision Data Management, 2006

More Related