| 1. |
- Ashjaei, Mohammad, et al.
(author)
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Response time analysis of multi-hop HaRTES Ethernet Switch networks
- 2014
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In: IEEE Int. Workshop Factory Commun. Syst. Proc. WFCS. - 9781479932351
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Conference paper (peer-reviewed)abstract
- In this paper we focus on micro-segmented switched-Ethernet networks with HaRTES switches. HaRTES switches provide synchronous and asynchronous real-time traffic scheduling, dynamic Quality-of-Service adaptation and transparent integration of real-time and non-real-time nodes. Herein we investigate the challenges of connecting multiple HaRTES switches in order to build multi-hop communication and we propose a method, named Distributed Global Scheduling, to handle the traffic forwarding in such an architecture while preserving the unique properties of the single HaRTES switch case. Moreover, we develop a response time analysis for the method. We also evaluate the level of pessimism embodied in the anal-ysis. Finally, we show the applicability of the proposed method in an industrial setting by applying it in an automotive case study.
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| 2. |
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| 3. |
- Bril, Reinder J., et al.
(author)
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Integrating Cache-Related Pre-emption Delays into Analysis of Fixed Priority Scheduling with Pre-emption Thresholds
- 2015
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In: Proceedings - Real-Time Systems Symposium. - 9781479972890 ; , s. 161-172
-
Conference paper (peer-reviewed)abstract
- Cache-related pre-emption delays (CRPD) have been integrated into the schedulability analysis of sporadic tasks with constrained deadlines for fixed-priority pre-emptive scheduling (FPPS). This paper generalizes that work by integrating CRPD into the schedulability analysis of tasks with arbitrary deadlines for fixed-priority pre-emption threshold scheduling (FPTS). The analysis is complemented by an optimal threshold assignment algorithm that minimizes CRPD. The paper includes a comparative evaluation of the schedulability ratios of FPPS and FPTS, for constrained-deadline tasks, taking CRPD into account.
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| 4. |
- Afshar, Sara, et al.
(author)
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Per Processor Spin-Lock Priority for Partitioned Multiprocessor Real-Time Systems
- 2014
-
Reports (other academic/artistic)abstract
- Two traditional approaches exist for a task that is blocked on a global resource; a task either performs a non-preemptive busy wait, i.e., spins, or suspends and releases the processor. Previously, we have shown that both approaches can be viewed as spinning either at the highest priority HP or at the lowest priority on the processor LP, respectively. Based on this view, previously we have generalized a task's blocking behavioral model, as spinning at any arbitrary priority level. In this paper, we focus on a particular class of spin-lock protocols from the introduced flexible spin-lock model where spinning is performed at a priority equal to or higher than the highest local ceiling of the global resources accessed on a processor referred to as CP spin-lock approach. In this paper, we assume that all tasks of a specific processor are spinning on the same priority level. Given this class and assumption, we show that there exists a spin-lock protocol in this range that dominates the classic spin-lock protocol which tasks spin on highest priority level (HP). However we show that this new approach is incomparable with the CP spin-lock approach. Moreover, we show that there may exist an intermediate spin-lock approach between the priority used by CP spin-lock approach and the new introduced spin-lock approach that can make a task set schedulable when those two cannot. We provide an extensive evaluation results comparing the HP, CP and the new proposed approach.
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| 5. |
- Afshar, Sara, et al.
(author)
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Per Processor Spin-Lock Priority for Partitioned Multiprocessor Real-Time Systems
- 2017
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In: Leibniz Transactions on Embedded Systems. - 2199-2002. ; :2
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Journal article (other academic/artistic)abstract
- Two traditional approaches exist for a task that is blocked on a global resource; a task either performs a non-preemptive busy wait, i.e., spins, or suspends and releases the processor. Previously, we have shown that both approaches can be viewed as spinning either at the highest priority HP or at the lowest priority on the processor LP, respectively. Based on this view, previously we have generalized a task's blocking behavioral model, as spinning at any arbitrary priority level. In this paper, we focus on a particular class of spin-lock protocols from the introduced flexible spin-lock model where spinning is performed at a priority equal to or higher than the highest local ceiling of the global resources accessed on a processor referred to as CP spin-lock approach. In this paper, we assume that all tasks of a specific processor are spinning on the same priority level. Given this class and assumption, we show that there exists a spin-lock protocol in this range that dominates the classic spin-lock protocol which tasks spin on highest priority level (HP). However we show that this new approach is incomparable with the CP spin-lock approach. Moreover, we show that there may exist an intermediate spin-lock approach between the priority used by CP spin-lock approach and the new introduced spin-lock approach that can make a task set schedulable when those two cannot. We provide an extensive evaluation results comparing the HP, CP and the new proposed approach.
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| 6. |
- Afshar, Sara, et al.
(author)
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Resource Sharing Under Global Scheduling with Partial Processor Bandwidth
- 2015
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In: 2015 10th IEEE International Symposium on Industrial Embedded Systems, SIES 2015 - Proceedings. - 9781467377119 ; , s. 195-206
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Conference paper (peer-reviewed)abstract
- Resource efficient approaches are of great importance for resource constrained embedded systems. In this paper, we present an approach targeting systems where tasks of a critical application are partitioned on a multi-core platform and by using resource reservation techniques, the remaining bandwidth capacity on each core is utilized for one or a set of non-critical application(s). To provide a resource efficient solution and to exploit the potential parallelism of the extra applications on the multi-core processor, global scheduling is used to schedule the tasks of the non-critical applications. Recently a specific instantiation of such a system has been studied where tasks do not share resources other than the processor. In this paper, we enable semaphore-based resource sharing among tasks within critical and non-critical applications using a suspension-based synchronization protocol. Tasks of non-critical applications have partial access to the processor bandwidth. The paper provides the systems schedulability analysis where blocking due to resource sharing is bounded. Further, we perform experimental evaluations under balanced and unbalanced allocation of tasks of a critical application to cores.
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| 7. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(author)
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Investigation of Implementing a Synchronization Protocol under Multiprocessors Hierarchical Scheduling
- 2009
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In: 2009 IEEE Conference on Emerging Technologies & Factory Automation. - : IEEE. - 9781424427277 - 9781424427284
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Conference paper (peer-reviewed)abstract
- In the multi-core and multiprocessor domain, there has been considerable work done on scheduling techniques assuming that real-time tasks are independent. In practice a typical real-time system usually share logical resources among tasks. However, synchronization in the multiprocessor area has not received enough attention.In this paper we investigate the possibilities of extending multiprocessor hierarchical scheduling to support an existing synchronization protocol (FMLP) in multiprocessor systems. We discuss problems regarding implementation of the synchronization protocol under the multiprocessor hierarchical scheduling.
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