POSIX-compatible application-defined scheduling in MaRTE OS

Rivas, Mario Aldea; Harbour, Michael González

doi:10.1109/emrts.2002.1019186

Cited by 23 publications

(15 citation statements)

References 5 publications

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“…A new trend in some recent operating system is to provide support for the development of a user level scheduler. This is the approach followed in MarteOS (Rivas and Harbour, 2001).…”

Section: Introductionmentioning

confidence: 99%

Rate Monotonic vs. EDF: Judgment Day

Buttazzo

2003

Embedded Software

121

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Abstract. Since the first results published in 1973 by Liu and Layland on the Rate Monotonic (RM) and Earliest Deadline First (EDF) algorithms, a lot of progress has been made in the schedulability analysis of periodic task sets. Unfortunately, many misconceptions still exist about the properties of these two scheduling methods, which usually tend to favor RM more than EDF. Typical wrong statements often heard in technical conferences and even in research papers claim that RM is easier to analyze than EDF, it introduces less runtime overhead, it is more predictable in overload conditions, and causes less jitter in task execution.Since the above statements are either wrong, or not precise, it is time to clarify these issues in a systematic fashion, because the use of EDF allows a better exploitation of the available resources and significantly improves system's performance. This paper compares RM against EDF under several aspects, using existing theoretical results, specific simulation experiments, or simple counterexamples to show that many common beliefs are either false or only restricted to specific situations.

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“…A new trend in some recent operating system is to provide support for the development of a user level scheduler. This is the approach followed in MarteOS (Rivas and Harbour, 2001).…”

Section: Introductionmentioning

confidence: 99%

Rate Monotonic vs. EDF: Judgment Day

Buttazzo

2003

Embedded Software

121

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“…Solche hierarchische Scheduling-Modelle existieren zwar bereits (z.B. im MaRTE OS [16]), jedoch nicht im Zusammenhang mit dynamisch begrenzten Ressourcenkapazitäten und Echtzeit-Anforderungen der Anwendungen. Letztere verlangen eine Abbildung der Kapazitäts-Grenzen der Anwendungen auf das Scheduling der einzelnen Tasks, was im Rahmen dieser Arbeit durch die angepassten Funktionen der CBS ermöglicht wird.…”

Section: Wissenschaftliche Beiträgeunclassified

Ein hierarchisches Scheduling-Modell für unbekannte Anwendungen mit schwankenden Ressourcenanforderungen

2015

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ZusammenfassungWeiche Echtzeitsysteme, die mit unbekannten, dynamisch gestarteten und gestoppten Anwendungen umgehen müssen, sind schwer zu analysieren in Hinblick auf ihre Planbarkeit. Ein solches System muss in der Lage sein, sich dynamisch an die tatsächlichen Anforderungen der Anwendungen anzupassen. IV AbstractSoft real-time systems that have to deal with unknown, dynamically loaded and stopped applications are hard to analyse for feasibility. Such systems must be capable to dynamically adapt themselves to actual requirements of applications. They further require mechanisms to control and resolve overload situations, which may arise while apps compete for common shared resources. Since estimations of actual execution times of activities are not available from the start, they have to be determined by the system during runtime. The estimations must be also adopted to fluctuations within the measured resource demands of the activities. In this PhD thesis an adaptive hierarchical scheduling model for a dynamic set of applications with fluctuating resource demands has been developed. On the lowest level the scheduler ensures correct execution of application tasks according to online approximations of their demands. On the higher levels isolation between the apps is provided while the scheduler continuously re-calibrates given capacities and performs local schedulability analysis for application tasks. In bottleneck situations an optimal degradation is applied by assigning one of different quality levels to the apps based on their resource estimations and priorities. Thereby, applications are activated in different operational modes. However, such reconfigurations must happen as rarely as possible, because they introduce an additional computational overhead for the system. With the proposed scheduling architecture the problem of proving schedulability is spatially partitioned and temporally distributed. Tests are performed portion-wise only when and where necessary. The model maintains feasibility until cost estimations violate custom safety buffers and resource bounds. In such cases a new optimal resource configuration is computed changing the quality of some apps. Periodic violations are also dedected automatically suppressing recurring reconfigurations in the system. The scheduling model was implemented with RTSJ and integrated within a soft real-time framework ARTOS. For evaluation of its scheduling mechanisms artificial apps were developed, which can produce real computational overhead within a platform following a certain load-profile. In our experiments new apps were run with a low priority until their modes were initially estimated. We were able to verify that (a) the system quickly establishes an optimal modes selection respecting priorities (b) it remains feasible when tasks reside within their tolerance limits (c)

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“…With the current kernel interface for application-defined scheduling [6] it is possible to simultaneously wait for a scheduling event and a kernel signal, and thus the new interface allows a much more efficient implementation. A similar interface would be required to specify a scheduling action to wait for the expiration of the budget of a group of timers.…”

Section: Support Package and Changes To The Underlying Operating Systemmentioning

confidence: 99%

“…The implementation is based on the GNAT compiler together with the applicationscheduling services described in [6], available in MaRTE OS [1], and extended with some new services that are necessary to support mutual exclusive synchronization using the SRP protocol [5]. Because group budget timers are not yet implemented in MaRTE OS, we will leave this functionality unimplemented in this version.…”

Section: Architecture Of This Implementationmentioning

confidence: 99%

“…In the run-time system level we need to implement a new support package and change some internal operations. The implementation will be based on the GNAT compiler and on our application-defined scheduling facilities [6] implemented on top of our MaRTE OS [1], which is an operating system for embedded real-time systems that conforms to the POSIX Minimal Real-Time System Profile [3] [4]. The application-defined scheduling facilities available in MaRTE OS are also being proposed for standardization under the POSIX standard [3].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Implementing an Application-Defined Scheduling Framework for Ada Tasking

Aldea

Miranda

Harbour

2004

Lecture Notes in Computer Science

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Abstract:A framework for application-defined scheduling and its corresponding application program interface (API) were defined during the last International Real-Time Ada Workshop, and are being proposed for standardization in the future revision of the Ada language. The framework allows applications to install one or more task schedulers capable of implementing a large variety of scheduling algorithms. This paper describes the implementation of this framework, both at the compiler and the run-time system levels. The objective of this work is to serve as a reference implementation in which the API can be evaluated and tested, and its performance can be assessed. We show that the amount of changes to the compiler is relatively small, and that the application scheduling capability can be supported with a small level of complexity.

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POSIX-compatible application-defined scheduling in MaRTE OS

Cited by 23 publications

References 5 publications

Rate Monotonic vs. EDF: Judgment Day

Rate Monotonic vs. EDF: Judgment Day

Ein hierarchisches Scheduling-Modell für unbekannte Anwendungen mit schwankenden Ressourcenanforderungen

Implementing an Application-Defined Scheduling Framework for Ada Tasking

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