The rate monotonic scheduling algorithm: exact characterization and average case behavior
05 Dec 1989-pp 166-171
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.
Abstract: An exact characterization of the ability of the rate monotonic scheduling algorithm to meet the deadlines of a periodic task set is represented. In addition, a stochastic analysis which gives the probability distribution of the breakdown utilization of randomly generated task sets is presented. It is shown that as the task set size increases, the task computation times become of little importance, and the breakdown utilization converges to a constant determined by the task periods. For uniformly distributed tasks, a breakdown utilization of 88% is a reasonable characterization. A case is shown in which the average-case breakdown utilization reaches the worst-case lower bound of C.L. Liu and J.W. Layland (1973). >
Citations
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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.
Abstract: 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 protocols solve the uncontrolled priority inversion problem. The priority ceiling protocol solves this uncontrolled priority inversion problem particularly well; it reduces the worst-case task-blocking time to at most the duration of execution of a single critical section of a lower-priority task. This protocol also prevents the formation of deadlocks. Sufficient conditions under which a set of periodic tasks using this protocol may be scheduled is derived. >
2,443 citations
21 Oct 2001
TL;DR: This paper presents a class of novel algorithms that modify the OS's real-time scheduler and task management service to provide significant energy savings while maintaining real- time deadline guarantees, and shows that these RT-DVS algorithms closely approach the theoretical lower bound on energy consumption.
Abstract: In recent years, there has been a rapid and wide spread of non-traditional computing platforms, especially mobile and portable computing devices. As applications become increasingly sophisticated and processing power increases, the most serious limitation on these devices is the available battery life. Dynamic Voltage Scaling (DVS) has been a key technique in exploiting the hardware characteristics of processors to reduce energy dissipation by lowering the supply voltage and operating frequency. The DVS algorithms are shown to be able to make dramatic energy savings while providing the necessary peak computation power in general-purpose systems. However, for a large class of applications in embedded real-time systems like cellular phones and camcorders, the variable operating frequency interferes with their deadline guarantee mechanisms, and DVS in this context, despite its growing importance, is largely overlooked/under-developed. To provide real-time guarantees, DVS must consider deadlines and periodicity of real-time tasks, requiring integration with the real-time scheduler. In this paper, we present a class of novel algorithms called real-time DVS (RT-DVS) that modify the OS's real-time scheduler and task management service to provide significant energy savings while maintaining real-time deadline guarantees. We show through simulations and a working prototype implementation that these RT-DVS algorithms closely approach the theoretical lower bound on energy consumption, and can easily reduce energy consumption 20% to 40% in an embedded real-time system.
1,265 citations
Cites methods from "The rate monotonic scheduling algor..."
...In this paper, we develop algorithms to integrate DVS mechanisms into the two most-studied real-time schedulers, Rate Monotonic (RM) and Earliest-Deadline-First (EDF) schedulers [13, 14, 17, 18, 27]....
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TL;DR: The paper presents exact schedulability analyses for real-time systems scheduled at runtime with a static priority pre-emptive dispatcher and the predictions that follow are seen to be in close agreement with the behaviour exhibited during simulation studies.
Abstract: The paper presents exact schedulability analyses for real-time systems scheduled at runtime with a static priority pre-emptive dispatcher. The tasks to be scheduled are allowed to experience internal blocking (from other tasks with which they share resources) and (with certain restrictions) to release jitter, such as waiting for a message to arrive. The analysis presented is more general than that previously published and subsumes, for example, techniques based on the Rate Monotonic approach. In addition to presenting the relevant theory, an existing avionics case study is described and analysed. The predictions that follow from this analysis are seen to be in close agreement with the behaviour exhibited during simulation studies.
1,168 citations
Cites background from "The rate monotonic scheduling algor..."
...j ( 8 ) The above equation assumes that task j executes as a continual periodic task (with period tj ) over the remaining interval....
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Book•
15 Jan 2000TL;DR: RTSJ's features and the thinking behind the specification's design are explained, which aims to provide a platform-a Java execution environment and application program interface (API) that lets programmers correctly reason about the temporal behavior of executing software.
Abstract: New languages, programming disciplines, operating systems, and software engineering techniques sometimes hold considerable potential for real-time software developers. A promising area of interest-but one fairly new to the real-time community-is object-oriented programming. Java, for example, draws heavily from object orientation and is highly suitable for extension to real-time and embedded systems. Recognizing this fit between Java and real-time software development, the Real-Time for Java Experts Group (RTJEG) began developing the real-time specification for Java (RTSJ) in March 1999 under the Java Community Process. This article explains RTSJ's features and the thinking behind the specification's design. The goal of the RTJEG, of which the authors are both members, was to provide a platform-a Java execution environment and application program interface (API)-that lets programmers correctly reason about the temporal behavior of executing software.
1,094 citations
22 Jan 2013
TL;DR: Premises of creation of Internet portal designed to provide access to participants of educational and scientific process for the joint creation, consolidation, concentration and rapid spreading of educationaland scientific information resources in its own depository are considered.
Abstract: Premises of creation of Internet portal designed to provide access to participants of educational and scientific process for the joint creation, consolidation, concentration and rapid spreading of educational and scientific information resources in its own depository are considered. CMS-based portal content management systems’ potentiality is investigated. Architecture for Internet portal of MES of Ukraine’s information resources is offered.
969 citations
Cites methods from "The rate monotonic scheduling algor..."
...[3] was used to verify the schedulability of the task set using the RM scheduling policy....
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References
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TL;DR: 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.
Abstract: 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. 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. It is also shown that full processor utilization can be achieved by dynamically assigning priorities on the basis of their current deadlines. A combination of these two scheduling techniques is also discussed.
7,067 citations
Book•
01 Apr 1986
TL;DR: In this paper, a broad cross-section of the literature available on one-dimensional empirical processes is summarized, with emphasis on real random variable processes as well as a wide-ranging selection of applications in statistics.
Abstract: Here is the first book to summarize a broad cross-section of the large volume of literature available on one-dimensional empirical processes. Presented is a thorough treatment of the theory of empirical processes, with emphasis on real random variable processes as well as a wide-ranging selection of applications in statistics. Featuring many tables and illustrations accompanying the proofs of major results, coverage includes foundations - special spaces and special processes, convergence and distribution of empirical processes, alternatives and processes of residuals, integral tests of fit and estimated empirical processes and martingale methods.
2,774 citations
TL;DR: 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+.
947 citations
Proceedings Article•
01 Dec 1986298 citations
06 Dec 1988
TL;DR: The authors describe the extended priority exchange algorithm, which can provide better aperiodic response than previous a periodic service algorithms, particularly for cases where the worst-case periodic load is high and little or no utilization is left for a server task.
Abstract: Real-time scheduling algorithms that provide responsive aperiodic service in the presence of hard real-time periodic tasks require the creation of a high-priority periodic server task for servicing aperiodic requests. The authors describe the extended priority exchange algorithm, which can provide better aperiodic response than previous aperiodic service algorithms, particularly for cases where the worst-case periodic load is high and little or no utilization is left for a server task. The extended-priority-exchange (EPE) algorithm attains better aperiodic responsiveness by exploiting unused time allocated to periodic tasks for aperiodic service. The average aperiodic response times for the EPE algorithm and four other aperiodic service algorithms (background, polling, deferrable server, and priority exchange) are compared for a range of periodic and aperiodic loads. Simulation results show that for a difference between the average and worst-case periodic load of only 12.5%, the EPE algorithm provides significantly better response times for aperiodic tasks. >
156 citations