The control of priority inversion in Ada

Levine, Gertrude

doi:10.1145/51634.51636

Cited by 7 publications

(3 citation statements)

References 2 publications

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“…An intermediate priority task is then prevented from preempting the (previously) low priority tasks because of their raised priorities. Assume that the high priority task aborts, yet a network message to reset the priorities of the low priority tasks is delayed [9]. The low priority tasks are then dispatched before the intermediate priority task, although their effective priority was needlessly raised -a clear inversion.…”

Section: Definitions and Related Workmentioning

confidence: 99%

Priority inversion with fungible resources

Levine

2012

Ada Lett.

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Priority inversion occurs when the execution of a task is unnecessarily delayed by the dispatch of a lower priority task. This anomaly can result in failure if it causes the delay of hard real-time tasks. Priority inheritance protocols have been developed to limit priority inversions during competition over shared resources. Such methods are designed for individually identifiable resource units. Other approaches are indicated when shared resources contain interchangeable resource units. Current practices with resource deadlock, a scheduling anomaly that has many characteristics in common with priority inversion, provide insight into the control of priority inversion with these fungible resources.

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Section: Definitions and Related Workmentioning

confidence: 99%

Priority inversion with fungible resources

Levine

2012

Ada Lett.

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“…That work, however, considers only two priorities (high and low). Research in languages such as Ada (Cornhill and Sha, 1987;Levine, 1988) also discusses the importance of preventing priority inversion in a general setting with rich priorities, but we are aware of no prior static language mechanisms for doing so.…”

Section: Introductionmentioning

confidence: 99%

Competitive parallelism: getting your priorities right

Muller

Acar

Harper

2018

Proc. ACM Program. Lang.

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Multi-threaded programs have traditionally fallen into one of two domains: cooperative and competitive. These two domains have traditionally remained mostly disjoint, with cooperative threading used for increasing throughput in compute-intensive applications such as scientific workloads and cooperative threading used for increasing responsiveness in interactive applications such as GUIs and games. As multicore hardware becomes increasingly mainstream, there is a need for bridging these two disjoint worlds, because many applications mix interaction and computation and would benefit from both cooperative and competitive threading.In this paper, we present techniques for programming and reasoning about parallel interactive applications that can use both cooperative and competitive threading. Our techniques enable the programmer to write rich parallel interactive programs by creating and synchronizing with threads as needed, and by assigning threads user-defined and partially ordered priorities. To ensure important responsiveness properties, we present a modal type system analogous to S4 modal logic that precludes low-priority threads from delaying high-priority threads, thereby statically preventing a crucial set of priority-inversion bugs. We then present a cost model that allows reasoning about responsiveness and completion time of well-typed programs. The cost model extends the traditional work-span model for cooperative threading to account for competitive scheduling decisions needed to ensure responsiveness. Finally, we show that our proposed techniques are realistic by implementing them as an extension to the Standard ML language.

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“…A scheduling priority anomaly occurs if a process is chosen for execution in an incorrect priority order. For example, in priority inversion, a high priority process waits for service while a lower priority process is allocated the CPU [12]. Priority inversion can be prevented by priority inheritance, where a server's priority is ordered based on the priority of its waiting processes.…”

Section: Priority Errorsmentioning

confidence: 99%

A Model for Anomalies of Software Engineering

Levine¹

Advances in Systems, Computing Sciences and Software Engineering

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We present a model for the anomalies of software engineering that cause system failures. Our model enables us to develop a classification scheme in terms of the types of errors that are responsible, as well as to identify the layers of a system architecture at which control mechanisms should be applied. 1 We borrow the term fungible from law to denote resource units that are interchangeable to the user.

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The control of priority inversion in Ada

Cited by 7 publications

References 2 publications

Priority inversion with fungible resources

Priority inversion with fungible resources

Competitive parallelism: getting your priorities right

A Model for Anomalies of Software Engineering

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