Journal ArticleDOI
Aperiodic task scheduling for real-time systems
Reads0
Chats0
TLDR
A new algorithm is presented, the Sporadic Server algorithm, which greatly improves response times for soft deadline a periodic tasks and can guarantee hard deadlines for both periodic and aperiodic tasks.Abstract:
This thesis develops the Sporadic Server (SS) algorithm for scheduling aperiodic tasks in real-time systems. The SS algorithm is an extension of the rate monotonic algorithm which was designed to schedule periodic tasks. This thesis demonstrates that the SS algorithm is able to guarantee deadlines for hard-deadline aperiodic tasks and provide good responsiveness for soft-deadline aperiodic tasks while avoiding the schedulability penalty and implementation complexity of previous aperiodic service algorithms. It is also proven that the aperiodic servers created by the SS algorithm can be treated as equivalently-sized periodic tasks when assessing schedulability. This allows all the scheduling theories developed for the rate monotonic algorithm to be used to schedule aperiodic tasks. For scheduling aperiodic and periodic tasks that share data, this thesis defines the interactions and schedulability impact of using the SS algorithm with the priority inheritance protocols. For scheduling hard-deadline tasks with short deadlines, an extension of the rate monotonic algorithm and analysis is developed. To predict performance of the SS algorithm, this thesis develops models and equations that allow the use of standard queueing theory models to predict the average response time of soft-deadline aperiodic tasks serviced with a high-priority sporadic server. Implementation methods are also developed to support the SS algorithm in Ada and on the Futurebus+.read more
Citations
More filters
Proceedings ArticleDOI
The rate monotonic scheduling algorithm: exact characterization and average case behavior
John P. Lehoczky,Lui Sha,Y. Ding +2 more
TL;DR: An exact characterization of the ability of the rate monotonic scheduling algorithm to meet the deadlines of a periodic task set and a stochastic analysis which gives the probability distribution of the breakdown utilization of randomly generated task sets are represented.
Journal ArticleDOI
Stack-based scheduling for realtime processes
TL;DR: It is shown how to extend the Priority Ceiling Protocol to handle: multiunit resources, which subsume binary semaphores and reader-writer locks; dynamic priority schemes, such as earliest-deadline-first (EDF), that use static “preemption levels”; sharing of runtime stack space between jobs.
Journal ArticleDOI
Real Time Scheduling Theory: A Historical Perspective
Lui Sha,Tarek Abdelzaher,Karl-Erik Årzén,Anton Cervin,Theodore P. Baker,Alan Burns,Giorgio Buttazzo,Marco Caccamo,John P. Lehoczky,Aloysius K. Mok +9 more
TL;DR: This 25th year anniversary paper for the IEEE Real Time Systems Symposium reviews the key results in real-time scheduling theory and the historical events that led to the establishment of the current real- time computing infrastructure.
Journal ArticleDOI
Hard Real-Time Scheduling: The Deadline-Monotonic Approach
TL;DR: Investigation of schedulability tests for sets of periodic processes whose deadlines are permitted to be less than their period finds that such a relaxation enables sporadic processes to be directly incorporated without alteration to the process model.
Proceedings ArticleDOI
Periodic resource model for compositional real-time guarantees
Insik Shin,Insup Lee +1 more
TL;DR: This work proposes a resource model to characterize a periodic resource allocation and presents exact schedulability conditions for the proposed resource model under the EDF and RM algorithms, and introduces a composition method that derives the timing requirements of a parent scheduler from the time requirements of its child schedulers in a compositional manner.
References
More filters
Book
Scheduling algorithms for multiprogramming in a hard real-time environment
C. L. Liu,James W. Layland +1 more
TL;DR: In this paper, the problem of multiprogram scheduling on a single processor is studied from the viewpoint of the characteristics peculiar to the program functions that need guaranteed service, and it is shown that an optimum fixed priority scheduler possesses an upper bound to processor utilization which may be as low as 70 percent for large task sets.
Book
Queueing Systems. Volume 1: Theory
TL;DR: The purpose of this document is to summarize the main points of the book written by Leonard Kleinrock, titled, ‘Queueing Systems’, which is about queueing systems.
Journal ArticleDOI
A Proof for the Queuing Formula: L = λW
TL;DR: In this paper, it was shown that if the three means are finite and the corresponding stochastic processes strictly stationary, and if the arrival process is metrically transitive with nonzero mean, then L = λW.
Journal ArticleDOI
Priority inheritance protocols: an approach to real-time synchronization
TL;DR: An investigation is conducted of two protocols belonging to the priority inheritance protocols class; the two are called the basic priority inheritance protocol and the priority ceiling protocol, both of which solve the uncontrolled priority inversion problem.
Proceedings ArticleDOI
The rate monotonic scheduling algorithm: exact characterization and average case behavior
John P. Lehoczky,Lui Sha,Y. Ding +2 more
TL;DR: An exact characterization of the ability of the rate monotonic scheduling algorithm to meet the deadlines of a periodic task set and a stochastic analysis which gives the probability distribution of the breakdown utilization of randomly generated task sets are represented.
Related Papers (5)
Scheduling Algorithms for Multiprogramming in a Hard-Real-Time Environment
C. L. Liu,James W. Layland +1 more
Priority inheritance protocols: an approach to real-time synchronization
The rate monotonic scheduling algorithm: exact characterization and average case behavior
John P. Lehoczky,Lui Sha,Y. Ding +2 more