| 21. |
- Afshar, Sara, et al.
(author)
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Resource Sharing among Prioritized Real-Time Applications on Multiprocessors
- 2015
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In: ACM SIGBED Review - Special Issue on the 6th International Workshop on Compositional Theory and Technology for Real-Time Embedded Systems. - : Association for Computing Machinery (ACM). ; , s. 46-55
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Conference paper (peer-reviewed)abstract
- In this paper, we propose a new protocol for handling resource sharing among prioritized real-time applications composed on a multiprocessor platform. We propose an optimal priority assignment algorithm which assigns unique priorities to the applications based on information in their interfaces. We have performed experimental evaluations to compare the proposed protocol (called MSOS-Priority) to the current state of the art locking protocols under multiprocessor partitioned scheduling, i.e., MPCP, MSRP, FMLP, MSOS, and OMLP. The valuations show that MSOS-Priority mostly performs significantly better than alternative approaches.
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| 22. |
- Afshar, Sara, et al.
(author)
-
Resource sharing in a hybrid partitioned/global scheduling framework for multiprocessors
- 2015
-
In: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA. - 9781467379298
-
Conference paper (peer-reviewed)abstract
- For resource-constrained embedded real-time systems, resource-efficient approaches are very important. Such an approach is presented in this paper, targeting systems where a critical application is partitioned on a multi-core platform and the remaining capacity on each core is provided to a noncritical application using resource reservation techniques. To exploit the potential parallelism of the non-critical application, global scheduling is used for its constituent tasks. Previously, we enabled intra-application resource sharing for such a framework, i.e. each application has its own dedicated set of resources. In this paper, we enable inter-application resource sharing, in particular between the critical application and the non-critical application. This effectively enables resource sharing in a hybrid partitioned/global scheduling framework on multiprocessors. For resource sharing, we use a spin-based synchronization protocol. We derive blocking bounds and extend existing schedulability analysis for such a system.
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| 23. |
- 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
-
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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| 24. |
- Afshar, Sara, et al.
(author)
-
Semi-partitioning under a Blocking-Aware Task Allocation
- 2015
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In: Proceedings - Real-Time Systems Symposium. - 9781467395076 ; , s. 379-379
-
Conference paper (peer-reviewed)abstract
- Semi-partitioned scheduling is a resource efficient scheduling approach compared to the conventional multiprocessor scheduling approaches in terms of system utilization and migration overhead. Semi-partitioned scheduling can better utilize processor bandwidth compared to the partitioned scheduling while introducing less overhead compared to the global scheduling. Various techniques have been proposed to schedule tasks in a semi-partitioned environment, however, they have used blockingagnostic allocation mechanisms in presence of resource sharing protocols. Since, the allocation mechanism can highly affect the system schedulability, in this paper we provide a blocking-aware allocation mechanism for semi-partitioned scheduling framework under a suspension-based resource sharing protocol. We have applied new heuristics for sorting the tasks in the algorithm that shows improvements upon system schedulability. Finally, we present our preliminary results.
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| 25. |
- Afshar, Sara Zargari, et al.
(author)
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An optimal spin-lock priority assignment algorithm for real-time multi-core systems
- 2017
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In: The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17.
-
Conference paper (peer-reviewed)abstract
- Support for exclusive access to shared (global) resources is instrumental in the context of embedded real-time multi-core systems, and mechanisms for achieving such access must be deterministic and efficient. There exist two traditional approaches for multiprocessors when a task requests a global resource that is locked by a task on a remote core: a spin-based approach, i.e. non-preemptive busy waiting for the resource to become available, and a suspension-based approach, i.e. the task relinquishes the processor. A suspension-based approach can be viewed as a spin-based approach where the lowest priority on a core is used during spinning, similar to a non-preemptive spin-based approach where the highest priority on a core is used. By taking such a view, we previously provided a general model for spinning, where any arbitrary priority can be used for spinning, i.e. from the lowest to the highest priority on a core. Targeting partitioned fixed-priority preemptive scheduled multiprocessors and spin-based approaches that use a fixed priority for spinning per core for all tasks, we aim at increasing the schedulability of multiprocessor systems by using the spin-lock priority per core as parameter. In this paper, we present (i) a generalization of the traditional worst-case response-time analysis for non-preemptive spin-based approaches addressing an arbitrary but fixed spin-lock priority per core, (ii) an optimal spin-lock priority assignment (OSPA) algorithm per core, i.e. an algorithm that will find a fixed spin-lock priority per core that will make the system schedulable, whenever such an assignment exists and, (iii) comparative evaluations of the OSPA algorithm with the spin-based and suspension-based approaches where OSPA showed up to 38% improvement compared to both approaches.
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| 26. |
- Al-Furoukh, Natalie, et al.
(author)
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ClpX stimulates the mitochondrial unfolded protein response (UPRmt) in mammalian cells
- 2015
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In: Biochimica et Biophysica Acta. Molecular Cell Research. - : Elsevier BV. - 0167-4889 .- 1879-2596. ; 1853:10, s. 2580-2591
-
Journal article (peer-reviewed)abstract
- Proteostasis is crucial for life and maintained by cellular chaperones and proteases. One major mitochondrial protease is the ClpXP complex, which is comprised of a catalytic ClpX subunit and a proteolytic ClpP subunit. Based on two separate observations, we hypothesized that ClpX may play a leading role in the cellular function of ClpXP. Therefore, we analyzed the effect of ClpX overexpression on a myoblast proteome by quantitative proteomics. ClpX overexpression results in the upregulation of markers of the mitochondria( proteostasis pathway, known as the "mitochondrial unfolded protein response" (UPRmt). Although this pathway is described in detail in Caenorhabditis elegans, it is not clear whether it is conserved in mammals. Therefore, we compared features of the classical nematode UPRmt with our mammalian ClpX-triggered UPRmt dataset. We show that they share the same retrograde mitochondria-to-nucleus signaling pathway that involves the key UPRmt transcription factor CHOP (also known as Ddit3, CEBPZ or GADD153). In conclusion, our data confirm the existence of a mammalian UPRmt that has great similarity to the C elegans pathway. Furthermore, our results illustrate that ClpX overexpression is a good and simple model to study the underlying mechanisms of the UPRmt in mammalian cells.
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| 27. |
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| 28. |
- Ashjaei, Mohammad, et al.
(author)
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Dynamic reconfiguration in HaRTES switched ethernet networks
- 2016
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In: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781509023394
-
Conference paper (peer-reviewed)abstract
- The ability of reconfiguring a system during runtime is essential for dynamic real-time applications in which resource usage is traded online for quality of service. The HaRTES switch, which is a modified Ethernet switch, holds this ability for the network resource, and at the same time it provides hard real-time support for both periodic and sporadic traffic. Although the HaRTES switch technologically caters this ability, a protocol to actually perform the dynamic reconfiguration is missing in multi-hop HaRTES networks. In this paper we introduce such a protocol that is compatible with the traffic scheduling method used in the architecture. We prove the correctness of the protocol using a model checking technique. Moreover, we conduct a set of simulation experiments to show the performance of the protocol and we also show that the reconfiguration process is terminated within a bounded time.
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| 29. |
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| 30. |
- Ashjaei, Mohammad, et al.
(author)
-
End-to-end Resource Reservations in Distributed Embedded Systems
- 2016
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In: Proceedings - 2016 IEEE 22nd International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2016. ; , s. 1-11
-
Conference paper (peer-reviewed)abstract
- The resource reservation techniques provide effective means to lower the software complexity, ensure predictability and allow flexibility during the development and execution of complex distributed embedded systems. In this paper we propose a new end-to-end resource reservation model for distributed embedded systems. The model is comprehensive in such a way that it supports end-to-end resource reservations on distributed transactions with various activation patterns that are commonly used in industrial control systems. The model allows resource reservations on processors and real-time network protocols. We also present timing analysis for the distributed embedded systems that are developed using the proposed model. The timing analysis computes the end-to-end response times as well as delays such as data age and reaction delays. The presented analysis also supports real-time networks that can autonomously initiate transmissions. Such networks are not supported by the existing analyses. We also include a case study to show the usability of the model and end-to-end timing analysis with resource reservations.
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