A contention-sensitive fine-grained locking protocol for multiprocessor real-time systems

Jarrett, Catherine E.; Ward, Bryan C.; Anderson, James H.

doi:10.1145/2834848.2834874

Cited by 14 publications

(5 citation statements)

References 14 publications

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“…Dynamic group locks (DGLs) ( Ward and Anderson, 2013 ; Ward, 2016 ) are the multi-resource lock variant of RNLP, and reader–writer RNLP (R/W RNLP) ( Ward and Anderson, 2014 ) provides a reader–writer extension to DGL. With contention-sensitive RNLP (C-RNLP) ( Jarrett et al, 2015 ), there is also an extension to RNLP that relaxes the strict FIFO ordering and tries to dynamically eliminate transitive blocking chains . The RNLP family provides the tightest blocking bounds known in the real-time literature, proven to be asymptotically optimal.…”

Section: Setting the Requirements For Real-time Locking In Roboticsmentioning

confidence: 99%

“…Conceptually, RNLP locks are always presented by using dedicated queues per resource in the literature ( Ward and Anderson, 2012 ; Ward and Anderson, 2013 ; Ward and Anderson, 2014 ; Ward, 2016 ). However, later work of the authors gives a hint to single-queue implementations of the non-reader–writer variants ( Jarrett et al, 2015 ). R/W RNLP cannot be implemented using a single queue, as its complex arbitration rules require multiple queues.…”

Section: Setting the Requirements For Real-time Locking In Roboticsmentioning

confidence: 99%

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Formal Verification of Real-Time Autonomous Robots: An Interdisciplinary Approach

Foughali

Zuepke

2022

Front. Robot. AI

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Due to the severe consequences of their possible failure, robotic systems must be rigorously verified as to guarantee that their behavior is correct and safe. Such verification, carried out on a model, needs to cover various behavioral properties (e.g., safety and liveness), but also, given the timing constraints of robotic missions, real-time properties (e.g., schedulability and bounded response). In addition, in order to obtain valid and useful verification results, the model must faithfully represent the underlying robotic system and should therefore take into account all possible behaviors of the robotic software under the actual hardware and OS constraints (e.g., the scheduling policy and the number of cores). These requirements put the rigorous verification of robotic systems at the intersection of at least three communities: the robotic community, the formal methods community, and the real-time systems community. Verifying robotic systems is thus a complex, interdisciplinary task that involves a number of disciplines/techniques (e.g., model checking, schedulability analysis, component-based design) and faces a number of challenges (e.g., formalization, automation, scalability). For instance, the use of formal verification (formal methods community) is hindered by the state-space explosion problem, whereas schedulability analysis (real-time systems) is not suitable for behavioral properties. Moreover, current real-time implementations of robotic software are limited in terms of predictability and efficiency, leading to, e.g., unnecessary latencies. This is flagrant, in particular, at the level of locking protocols in robotic software. Such situation may benefit from major theoretical and practical findings of the real-time systems community. In this paper, we propose an interdisciplinary approach that, by joining forces of the different communities, provides a scalable and unified means to efficiently implement and rigorously verify real-time robots. First, we propose a scalable two-step verification solution that combines formal methods and schedulability analysis to verify both behavioral and real-time properties. Second, we devise a new multi-resource locking mechanism that is efficient, predictable, and suitable for real-time robots and show how it improves the latter’s real-time behavior. In both cases, we show, using a real drone example, how our approach compares favorably to that in the literature. This paper is a major extension of the RTCSA 2020 publication “A Two-Step Hybrid Approach for Verifying Real-Time Robotic Systems.”

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Section: Setting the Requirements For Real-time Locking In Roboticsmentioning

confidence: 99%

Section: Setting the Requirements For Real-time Locking In Roboticsmentioning

confidence: 99%

Formal Verification of Real-Time Autonomous Robots: An Interdisciplinary Approach

Foughali

Zuepke

2022

Front. Robot. AI

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“…In 2015, Jarrett et al [117] introduced a contention-sensitive variant of the RNLP [201], denoted C-RNLP. In contrast to the original RNLP, and the vast majority of other protocols considered herein, the C-RNLP exploits knowledge of maximum critical section lengths at runtime to react dynamically to actual contention levels.…”

Section: Asymptotically Optimal Multiprocessor Real-time Lockingmentioning

confidence: 99%

“…In recent overhead-oriented work, Nemitz et al [158,160] added a fastpath to the RNLP [201] to optimize for the common case of non-nested lock acquisitions, and Afshar et al [10] presented an implementation of spin locks with flexible spin priorities [5]. Motivated by the fact that the contentionsensitive C-RNLP [117] exhibits relatively high acquisition and release overheads due to its complex request-sequencing rules, Nemitz et al [159] went a significant step further and introduced a novel and rather unconventional approach to implementing locking protocols. Specifically, Nemitz et al…”

Section: Rtos and Programming Language Integrationmentioning

confidence: 99%

Multiprocessor Real-Time Locking Protocols: A Systematic Review

Brandenburg

2019

Preprint

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We systematically survey the literature on analytically sound multiprocessor real-time locking protocols from 1988 until 2018, covering the following topics:• progress mechanisms that prevent the lock-holder preemption problem (Section 3),• spin-lock protocols (Section 4),• binary semaphore protocols (Sections 5 and 6),• independence-preserving (or fully preemptive) locking protocols (Section 7),• reader-writer and k-exclusion synchronization (Section 8),• support for nested critical sections (Section 9), and • implementation and system-integration aspects (Section 10).A special focus is placed on the suspension-oblivious and suspension-aware analysis approaches for semaphore protocols, their respective notions of priority inversion, optimality criteria, lower bounds on maximum priority-inversion blocking, and matching asymptotically optimal locking protocols.

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“…Most of them are based on priority inheritance. In particular Jarrett et al [17] apply priority inheritance to multi-cores and propose a resource management protocol which bounds the access latency to a shared resource. Negrean et al [20] provide a method to compute the blocking time induced by concurrent tasks in order to determine their response time.…”

Section: Related Workmentioning

confidence: 99%

Tightening Contention Delays While Scheduling Parallel Applications on Multi-core Architectures

Rouxel

Derrien

Puaut

2017

ACM Trans. Embed. Comput. Syst.

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Multi-core systems are increasingly interesting candidates for executing parallel real-time applications, in avionic, space or automotive industries, as they provide both computing capabilities and power efficiency. However, ensuring that timing constraints are met on such platforms is challenging, because some hardware resources are shared between cores.Assuming worst-case contentions when analyzing the schedulability of applications may result in systems mistakenly declared unschedulable, although the worst-case level of contentions can never occur in practice. In this paper, we present two contention-aware scheduling strategies that produce a time-triggered schedule of the application's tasks. Based on knowledge of the application's structure, our scheduling strategies precisely estimate the effective contentions, in order to minimize the overall makespan of the schedule. An Integer Linear Programming (ILP) solution of the scheduling problem is presented, as well as a heuristic solution that generates schedules very close to ones of the ILP (5 % longer on average), with a much lower time complexity. Our heuristic improves by 19% the overall makespan of the resulting schedules compared to a worst-case contention baseline.

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A contention-sensitive fine-grained locking protocol for multiprocessor real-time systems

Cited by 14 publications

References 14 publications

Formal Verification of Real-Time Autonomous Robots: An Interdisciplinary Approach

Formal Verification of Real-Time Autonomous Robots: An Interdisciplinary Approach

Multiprocessor Real-Time Locking Protocols: A Systematic Review

Tightening Contention Delays While Scheduling Parallel Applications on Multi-core Architectures

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