| 1. |
- Becker, Matthias, 1986-, et al.
(författare)
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Partitioning and Analysis of the Network-on-Chip on a COTS Many-Core Platform
- 2017
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Ingår i: 23rd IEEE Real-Time and Embedded Technology and Applications Symposium RTAS'17. - 9781509052691 ; , s. 101-112
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Konferensbidrag (refereegranskat)abstract
- Many-core processors can provide the computational power required by future complex embedded systems. However, their adoption is not trivial, since several sources of interference on COTS many-core platforms have adverse effects on the resulting performance. One main source of performance degradation is the contention on the Network-on-Chip, which is used for communication among the compute cores via the off- chip memory. Available analysis techniques for the traversal time of messages on the NoC do not consider many of the architectural features found on COTS platforms. In this work, we target a state-of-the-art many-core processor, the Kalray MPPA R . A novel partitioning strategy for reducing the contention on the NoC is proposed. Further, we present an analysis technique dedicated to the proposed partitioning strategy, which considers all architectural features of the COTS NoC. Additionally, it is shown how to configure the parameters for flow-regulation on the NoC, such that the Worst-Case Traversal Time (WCTT) is minimal and buffers never overflow. The benefits of our approach are evaluated based on extensive experiments that show that contention is significantly reduced compared to the unconstrained case, while the proposed analysis outperforms a state-of-the-art analysis for the same platform. An industrial case study shows the tightness of the proposed analysis.
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| 2. |
- Gutiérrez, M., et al.
(författare)
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Synchronization quality of IEEE 802.1AS in large-scale industrial automation networks.
- 2017
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Ingår i: Proceedings of the IEEE Real-Time and Embedded Technology and Applications Symposium, RTAS. - : Institute of Electrical and Electronics Engineers Inc.. - 9781509052691 ; , s. 273-282
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Konferensbidrag (refereegranskat)abstract
- Industry 4.0 and Industrial Internet of Things projects work towards adoption of standard IT technologies for real-time control networks in industrial automation. For this the IEEE 802.1 Time-Sensitive Networking (TSN) Task Group has developed and continues to develop a set of standards. One of these standards is the IEEE 802.1AS clock synchronization protocol. IEEE 802.1AS can be used to enable time-triggered communication as well as to coordinate distributed actions in industrial networks. In this paper we study the synchronization quality of IEEE 802.1AS and we are interested in whether the clocks can be synchronized with sufficiently low error such that the protocol can be used for demanding industrial automation applications. In particular, we study the protocol behavior in large-scale networks while considering critical implementation details. We report analytical worst-case results as well as probabilistic results based on simulations, that show that implementation details such as the PHY jitter and the clock granularity have a big impact on the time synchronization precision.
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| 3. |
- Voudouris, Petros, 1987, et al.
(författare)
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Timing-anomaly free dynamic scheduling of task-based parallel applications
- 2016
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Ingår i: Proceedings of the IEEE Real-Time and Embedded Technology and Applications Symposium, (RTAS 2017). Pittsburgh, PA, APR 18-21, 2017. - 1545-3421. - 9781509052691 ; 0, s. 365-376
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Konferensbidrag (refereegranskat)abstract
- Multicore architectures can provide high predictable performance through parallel processing. Unfortunately, computing the makespan of parallel applications is overly pessimistic either due to load imbalance issues plaguing static scheduling methods or due to timing anomalies plaguing dynamic scheduling methods. This paper contributes with an anomaly-free dynamic scheduling method, called Lazy, which is non-preemptive and non-greedy in the sense that some ready tasks may not be dispatched for execution even if some processors are idle. Assuming parallel applications using contemporary taskbased parallel programming models, such as OpenMP, the general idea of Lazy is to avoid timing anomalies by assigning fixed priorities to the tasks and then dispatch selective highestpriority ready tasks for execution at each scheduling point. We formally prove that Lazy is timing-anomaly free. Unlike all the commonly-used dynamic schedulers like breadth-first and depth-first schedulers (e.g., CilkPlus) that rely on analytical approaches to determine an upper bound on the makespan of parallel application, a safe makespan of a parallel application is computed by simulating Lazy. Our experimental results show that the makespan computed by simulating Lazy is much tighter and scales better as demonstrated by four parallel benchmarks from a task-parallel benchmark suite in comparison to the state-of-the-art.
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| 4. |
- Zhang, Xinhai, et al.
(författare)
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A case study on achieving fair data age distribution in vehicular communications
- 2017
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Ingår i: Proceedings of the IEEE Real-Time and Embedded Technology and Applications Symposium, RTAS. - : IEEE. - 9781509052691 ; , s. 307-317
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Konferensbidrag (refereegranskat)abstract
- In vehicular communication protocol stacks, received messages may not always be decoded successfully due to the complexity of the decoding functions, the uncertainty of the communication load and the limited computation resources. Even worse, an improper implementation of the protocol stack may cause an unfair data age distribution among all the communicating vehicles (the receiving bias problem). In such cases, some vehicles are almost locked out of the vehicular communication, causing potential safety risk in scenarios such as intersection passing. To our knowledge, this problem has not been systematically studied in the fields of vehicular communication and intelligent transport systems (ITS). This paper analyzes the root of the receiving bias problem and proposes architectural solutions to balance data age distribution. Simulation studies based on commercial devices demonstrate the effectiveness of these solutions. In addition, our system has been successfully applied during the Grand Cooperative Driving Challenge, where complicated scenarios involving platooning maneuvering and intersection coordination were conducted.
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