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| 2. |
- Behnam, Moris, et al.
(författare)
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Synchronization protocols for hierarchical real-time scheduling frameworks
- 2008
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Ingår i: Proceedings of the 1st Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS'08) in conjunction with the 29th IEEE International Real-Time Systems Symposium (RTSS'08), Barcelona, Spain.
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Konferensbidrag (refereegranskat)
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| 3. |
- Behnam, Moris, et al.
(författare)
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Towards Hierarchical Scheduling in VxWorks
- 2008
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Ingår i: OSPERT 2008, Proceedings of the Fourth International Workshop on Operating Systems Platforms for Embedded Real-Time Applications. ; , s. 63-72
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Konferensbidrag (refereegranskat)abstract
- Over the years, we have worked on hierarchical schedulingframeworks from a theoretical point of view. In thispaper we present our initial results of the implementationof our hierarchical scheduling framework in a commercialoperating system VxWorks. The purpose of the implementationis twofold: (1) we would like to demonstrate feasibilityof its implementation in a commercial operating system,without having to modify the kernel source code, and (2) wewould like to present detailed figures of various key propertieswith respect to the overhead of the implementation.During the implementation of the hierarchical scheduler,we have also developed a number of simple task schedulers.We present details of the implementation of Rate-Monotonic(RM) and Earliest Deadline First (EDF) schedulers. Finally,we present the design of our hierarchical schedulingframework, and we discuss our current status in the project.
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| 4. |
- Hallmans, Daniel, et al.
(författare)
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Towards using the Graphics Processing Unit (GPU) for Embedded Systems
- 2012
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Ingår i: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA 2012. ; , s. Article number: 6489715-
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Konferensbidrag (refereegranskat)abstract
- The Graphics Processing Unit (GPU) is becoming a very powerful platform to accelerate graphics and dataparallel compute-intensive applications. It gives a high performance and at the same time it has a low power consumption. This combination is of high performance and low power consumption is useful when it comes to building an embedded system. In this paper we are looking at the possibility to use a combination of CPU and GPU to provide performance metrics that are required in an embedded system. In particular we look at requirements inherent in the process and power industries where we believe that the GPU has the potential to be a useful and natural element in future embedded system architectures.
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| 5. |
- Moghaddami Khalilzad, Nima, et al.
(författare)
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On Adaptive Hierarchical Scheduling of Real-time Systems Using a Feedback Controller
- 2011
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Ingår i: 3rd Workshop on Adaptive and Reconfigurable Embedded Systems (APRES'11).
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Konferensbidrag (refereegranskat)abstract
- Hierarchical scheduling provides predictable timing and temporal isolation; two properties desirable in real-time embedded systems. In hierarchically scheduled systems, subsystems should receive a sufficient amount of CPU resources in order to be able to guarantee timing constraints of its internal parts (tasks). In static systems, an exact amount of CPU resource can be allocated to a subsystem. However, in dynamic systems, where execution times of tasks vary considerably during runtime, it is desirable to give a dynamic portion of the CPU given the current load situation. In this paper we present a feedback control approach for adapting the amount of CPU resource that is allocated to subsystems during run-time such that each subsystem receives sufficient resources while keeping the number of deadline violations to a minimum. We also show an example simulation where the controller adapts the budget of a subsystem.
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| 6. |
- Moghaddami Khalilzad, Nima, et al.
(författare)
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Towards Adaptive Hierarchical Scheduling of Real-Time Systems
- 2011
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Ingår i: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA, 2011. - New York : IEEE. - 9781457700187 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- Hierarchical scheduling provides a modular framework for integrating, scheduling and guaranteeing timing constraints of compositional real-time systems. In such a scheduling framework, all modules should receive a sufficient portion of the shared CPU to be able to guarantee timing constraints of their internal parts. In dynamic systems i.e., systems where the execution time of tasks are subjected to sudden and drastic changes during run-time, assigning fixed CPU portions to the modules is conducive to either low CPU utilization or numerous task deadline misses. In this paper, in order to address this problem, we propose an adaptive CPU allocation method which dynamically assigns CPU portions to the modules during run-time based on their current CPU demand. Besides, the presented approach is evaluated using a series of different simulations. In addition, we present a method for scheduling modules in situations when the CPU resource is not sufficient for scheduling all modules. We introduce the notion of module (subsystem) criticality, and in an overload situation we distribute the CPU resource based on the criticality of modules.
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| 7. |
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| 8. |
- Åsberg, Mikael, et al.
(författare)
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A Loadable Task Execution Recorder for Hierarchical Scheduling in Linux
- 2011
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Ingår i: Proceedings - 17th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2011. - 9780769545028 ; , s. 380-387
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Konferensbidrag (refereegranskat)abstract
- This paper presents a Hierarchical Scheduling Framework (HSF) recorder for Linux-based operating systems. The HSF-recorder is a loadable kernel module that is capable of recording tasks and servers without requiring any kernel modifications. Hence, it complies with the reliability and stability requirements in the area of embedded systems where proven versions of Linux are preferred. The recorder is built upon the loadable real-time scheduler framework RESCH (REal-time SCHed- uler). We evaluate our recorder by comparing the overhead of this solu- tion against two other recorders. Also, the tracing accuracy of the HSF- recorder is tested by running a media-processing task together with periodic real-time Linux tasks in combination with servers. We experiment with different task parameters and scheduling strategies and measure the performance of the media-processing task. The tests are recorded with the HSF-recorder, and the Ftrace recorder, in order to show the correctness of the experiments and the HSF-recorder itself.
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| 9. |
- Åsberg, Mikael, et al.
(författare)
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A loadable task execution recorder for Linux
- 2010
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Ingår i: Proceedings of the 1st International Workshop on Analysis Tools and Methodologies for Embedded and Real-time Systems. - Brussels, Belgium.
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Konferensbidrag (refereegranskat)
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| 10. |
- Åsberg, Mikael, et al.
(författare)
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An Experimental Evaluation of Synchronization Protocol Mechanisms in the Domain of Hierarchical Fixed-Priority Scheduling
- 2013
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Ingår i: ACM International Conference Proceeding Series, 2013. - New York, NY, USA : ACM. - 9781450320580 ; , s. 77-85
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Konferensbidrag (refereegranskat)abstract
- This paper presents an extensive implementation study where we evaluate and compare different synchronization protocol mechanisms within the domain of two-level hierarchical fixed-priority preemptive scheduling. These protocol mechanisms include HSRPnP (Hierarchical Stack Resource Policy no Payback), HSRPwP (Hierarchical Stack Resource Policy with Payback), SIRAP (Subsystem Integration and Resource Allocation Policy), RRP (Rollback Resource Policy) and SRPwD (Stack Resource Policy with Donation). In an attempt to shed new light to the research in this area, we focus on the actual software implementation of these protocols in a widely used real-time operating system (VxWorks). This study is not based on worst-case schedulability analysis which is the most common angle of work in this research field. All five protocols have been implemented, tested and executed for several months with many different parameters, for example; variant number of subsystems, number of resources, system utilization settings, resource allocation strategies etc. These tests generated a large amount of useful data, for example, protocol overhead, effective subsystem utilization, number of protocol mechanism invocations etc. Due to the large complexity and size of this data, we analyzed the data with state-of-the-art statistical methods and tools (Principal Component Analysis) in order to grasp the efficiency of the protocols with respect to a large number of different parameters.
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