Computing Reviews
Today's Issue Hot Topics Search Browse Recommended My Account Log In
Review Help
Search
The limited-preemptive feasibility of real-time tasks on uniprocessors
Thekkilakattil A., Dobrin R., Punnekkat S. Real-Time Systems51 (3):247-273,2015.Type:Article
Date Reviewed: Oct 27 2015

When it comes to real-time systems, the schedulability of a given task set will always be more likely if preemption of the running task is permitted. Preemption does, however, have some drawbacks, one of which is time spent switching tasks, while another, according to the authors, is the over-estimation of the worst-case execution time for tasks due to the variability that preemption introduces. Limited preemption is a midway point where a task may only be preempted at certain points. One obvious appeal is the simplified design permitted for critical section synchronization.

The authors look at the impact on scheduling feasibility that the limited preemptive paradigm provides. Much of the paper is dedicated to deriving the simple (and intuitive) limit that the longest non-preemptive section over all tasks must be less than half of the shortest deadline once the central processing unit (CPU) speed-up has been taken into account. Admittedly, the authors phrase it in terms of the required CPU speed-up to ensure schedule feasibility given non-linear scaling of the execution time with processor speed. They do, however, eventually require the scaling to be linear to be able to provide an upper bound.

The final part of the paper looks at the impact that multiple cores or processors have on the schedulability of a given task set. Once again, the final derived lemma can be simply stated that as long as the shortest deadline is less than or equal to the longest non-preemptive execution segment, no more than three processors are required to ensure schedulability.

Reviewer:  Bernard Kuc Review #: CR143890 (1601-0066)
Bookmark and Share
  Editor Recommended
Featured Reviewer
 
 
Real-Time Systems And Embedded Systems (D.4.7 ... )
 
 
Real-Time And Embedded Systems (C.3 ... )
 
Would you recommend this review?
yes
no
Other reviews under "Real-Time Systems And Embedded Systems": Date
Real-time software techniques
Heath W., Van Nostrand Reinhold Co., New York, NY, 1991. Type: Book (9780442003050)
Aug 1 1991
Developing safety systems
Pyle I., Prentice-Hall, Inc., Upper Saddle River, NJ, 1991. Type: Book (9780132042987)
Jul 1 1992
Real-time systems with transputers
Zedan H.  Real-time systems with transputers,York, UK,Sep 18-20, 1990,1990. Type: Whole Proceedings
Apr 1 1992
more...

E-Mail This Printer-Friendly
Send Your Comments
Contact Us
Reproduction in whole or in part without permission is prohibited.   Copyright 1999-2024 ThinkLoud®
Terms of Use
| Privacy Policy