Cost enforcement and deadline monitoring in the real-time specification for Java

Wellings, Andy; Bollella, Gregory; Dibble, Peter; Holmes, David

doi:10.1109/isorc.2004.1300332

Cited by 6 publications

(5 citation statements)

References 1 publication

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“…consumes to perform its function. However, the monitoring facilities and event handling mechanisms provided by these platforms are not usually integrated with their scheduling facilities [11]. As a result, the platform cannot enforce and monitor real-time properties of threads such as their allowed execution times and deadlines.…”

Section: Related Workmentioning

confidence: 99%

“…As a result, the platform cannot enforce and monitor real-time properties of threads such as their allowed execution times and deadlines. Real-Time Specification for Java (RTSJ) [11] is introduced to integrate scheduling of threads with the execution time monitoring facilities and enforce execution budgets on them in Java. For Ada applications and particularly the Ada Ravenscar profile [12] different kernels such as ORK [13] have been introduced to enforce and manage task budgets and handle critical real-time events.…”

Section: Related Workmentioning

confidence: 99%

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Monitoring capabilities of schedulers in model-driven development of real-time systems

Saadatmand

Sjödin

Mustafa

2012

Proceedings of 2012 IEEE 17th International Conference on Emerging Technologies &Amp; Factory Automation (ETFA 2012)

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Model-driven development has the potential to reduce the design complexity of real-time embedded systems by increasing the abstraction level, enabling analysis at earlier phases of development, and automatic generation of code from the models. In this context, capabilities of schedulers as part of the underlying platform play an important role. They can affect the complexity of code generators and how the model is implemented on the platform. Also, the way a scheduler monitors the timing behaviors of tasks and schedules them can facilitate the extraction of runtime information. This information can then be used as feedback to the original model in order to identify parts of the model that may need to be re-designed and modified. This is especially important in order to achieve round-trip support for model-driven development of real-time systems. In this paper, we describe our work in providing such monitoring features by introducing a second layer scheduler on top of the OSE real-time operating system's scheduler. The goal is to extend the monitoring capabilities of the scheduler without modifying the kernel. The approach can also contribute to the predictability of applications by bringing more awareness to the scheduler about the type of real-time tasks (i.e., periodic, sporadic, and aperiodic) that are to be scheduled and the information that should be monitored and logged for each type.

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Section: Related Workmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Monitoring capabilities of schedulers in model-driven development of real-time systems

Saadatmand

Sjödin

Mustafa

2012

Proceedings of 2012 IEEE 17th International Conference on Emerging Technologies &Amp; Factory Automation (ETFA 2012)

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“…Specifically, the RTSJ defines a cost enforcement model, whereby a periodic real-time thread is suspended when it consumes more CPU time (budget) than it requested. The overall goal of this mechanism is to ensure that the run-time behaviour of the system cannot undermine the system feasibility analysis without the explicit intervention of the program (Wellings et al 2004). It also attempts to provide an environment in which an errant thread can continue to execute and yet not impact the guaranteed execution time given to other threads in the system.…”

mentioning

confidence: 99%

Cost enforcement in the real-time specification for Java

Santos

Wellings

2007

Real-Time Syst

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The Real-Time Specification for Java (RTSJ) provides an integrated approach to scheduling periodic real-time threads and monitoring their CPU execution time. It defines a cost enforcement model whereby a periodic real-time thread is suspended when it consumes more CPU time (budget) than it requested in a single release. However, compliant implementations need not support this model, as the underlying operating systems mechanisms are not widely available. Consequently, experience with the model is limited (it is generally not provided in most implementations of the RTSJ). In previous work we showed, using model checking techniques, that the current version of the cost enforcement model can, under certain unlikely scenarios, allow a periodic thread more than its CPU budget in a single period. Such a behaviour can undermine any schedulability analysis that has been undertaken. In this paper, we present a revised formal model, which corrects this anomalous behaviour, and evaluate its properties. We also extend the formal model, so it allows support for real-time threads with sporadic and aperiodic releases, and show how our revised cost enforcement model is valid for all types of threads.

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“…With more years to consider cost enforcement, and the help of an implementation effort that includes cost enforcement [25], the specification's treatment of cost enforcement has been improved [28]. RTSJ version 1.0 was clear enough that it has been possible to get to a workable definition by interpreting the specification, but some areas will require extensions to the APIs that cannot be called "minor changes."…”

Section: Cost Enforcement and Blockingmentioning

confidence: 99%

“…RTSJ version 1.0 was clear enough that it has been possible to get to a workable definition by interpreting the specification, but some areas will require extensions to the APIs that cannot be called "minor changes." For example, cost enforcement for sporadic real-time threads [28] needs further consideration.…”

Section: Cost Enforcement and Blockingmentioning

confidence: 99%