| 1. |
- Liu, Meng, et al.
(författare)
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A Server-based Approach for Overrun Management in Multi-Core Real-Time Systems
- 2014
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Konferensbidrag (refereegranskat)abstract
- This paper presents a server-based framework for task overrun management in multi-core real-time systems. Unlike most existing scheduling methods which usually assume a single upper bound of the Worst-Case Execution Time (WCET) for each task, our approach targets scenarios with task overruns. The main idea of our framework is to employ Synchronized Deferrable Servers (SDS) to deal with globally scheduled task overruns, while a partitioned scheduling approach is applied on regular task executions. Moreover, we provide a deterministic Worst- Case Response Time (WCRT) analysis focusing on hard timing constraints, along with a probabilistic analysis of Deadline Miss Ratio (DMR) for soft real-time applications. In the evaluation phase, we have implemented two types of experiments evaluating different timing constraints.
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| 2. |
- Liu, Meng, et al.
(författare)
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An Adaptive Server-Based Scheduling Framework with Capacity Reclaiming and Borrowing
- 2014
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Ingår i: RTCSA 2014 - 20th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications. - 9781479939534 ; , s. Article number 6910548-
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present a new reservation based scheduling framework for soft real-time systems using EDF algorithm (called CARB-EDF). This framework has the features of Capacity Adaptation, Reclaiming and Borrowing. This framework can simplify the initial configuration of the system, where the system designer does not need to provide any estimations of task execution times. We also present a Chebyshev’s inequality based predictor to estimate task execution times. A number of simulation-based experiments have been implemented. According to the results compared with some related works, our scheduling framework can provide a better performance with acceptable extra scheduling overhead.
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| 3. |
- 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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| 4. |
- 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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| 5. |
- Åsberg, Mikael, et al.
(författare)
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Execution Time Monitoring in Linux
- 2009
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Ingår i: Proceedings of the Work-In-Progress (WIP) session of 14th IEEE International Conference on Emerging Techonologies and Factory (ETFA'09). - 9781424427284
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Konferensbidrag (refereegranskat)abstract
- This paper presents an implementation of an Execution Time Monitor (ETM) which can be applied in a resource management framework, such as the one proposed in the Open Media Platform (OMP) [4]. OMP is a European project which aims at creating an open, flexible and resource efficient software architecture for mobile devices such as cell phones and handsets. One of its goals is to open up the possibility for software portability and fast integration of applications, in order to decrease development costs. The task of the ETM is to measure task execution time and provide this information to the scheduler which then can schedule tasks in a more efficient and dynamic way. This implementation is our first step towards a full resource management framework that later will include a hierarchical scheduler, for soft real-time systems.
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| 6. |
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| 7. |
- Åsberg, Mikael, et al.
(författare)
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Towards Hierarchical Scheduling in Linux/Multi-core Platform
- 2010
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Ingår i: 15th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA 2010). - 9781424468508
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Konferensbidrag (refereegranskat)abstract
- This paper proposes the implementation of 4 different scheduling strategies for combining multi-core scheduling with hierarchical scheduling. Three of the scheduling schemes are analyzable with state-of-the-art schedulability analysis theory, available in the real-time systems community. Our idea is to implement these hierarchical multi-core scheduling strategies in a Linux based operating system, without modifying the kernel, and evaluate them. As of now, we have developed/implemented a prototype two-level hierarchical scheduling framework (HSF) in Linux (uni-core), which supports fixed priority preemptive scheduling (FPPS) of periodic servers at the top level, and FPPS of periodic tasks at the second level. The HSF is based on the REal-time SCHeduler (RESCH) framework.(1)
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| 8. |
- Åsberg, Mikael, et al.
(författare)
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Towards Partitioned Hierarchical Real-Time Scheduling on Multi-core Processors
- 2013
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Konferensbidrag (refereegranskat)abstract
- This paper extends previous work on hierarchical scheduling to multi-core systems. We have implemented partitioned multi-core scheduling of servers in the Linux kernel, using the scheduling framework ExSched. Neither ExSched nor the presented scheduler require any modifications to the Linux kernel. Hence, this makes the installation and kernel-version updates easier. We also present a user-space simulator which can be used when developing new multi-core hierarchical schedulers (plug-ins) for ExSched. We evaluate the overhead of our new multi-core hierarchical scheduler and compare it to a single-core hierarchical scheduler. Our results can be useful for developers that want to minimize the scheduler overhead when using partitioned hierarchical multi-core scheduling.
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| 9. |
- Åsberg, Mikael, et al.
(författare)
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Towards Real-Time Scheduling of Virtual Machines Without Kernel Modifications
- 2011
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Ingår i: 16th IEEE International Conference on Emerging Technology and Factory Automation (ETFA'11), Work-in-Progress (WiP) session. - Toulouse, France. - 9781457700187
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Konferensbidrag (refereegranskat)abstract
- Virtualization is a well used technique in the area of internet server systems for managing several (legacy) applications on a single physical machine. These applications do not have strict time deadlines, which also reflects how these applications are scheduled. Using virtualization in an embedded real-time systems context is of course attractive, since we want to pack as much software as possible on a, as small as possible, hardware platform. The problem is that this kind of software does not easily cope well together, in the aspect of time related properties. Hence, we need a new mechanism, i.e., a scheduler, that can satisfy the timing requirements of each application. However, scheduler implementations typically require modifications to middleware or kernel and this is not acceptable in the area embedded systems, due to stability and reliability reasons. Hence, in this paper, we propose a framework for scheduling (soft real-time) applications residing in separate operating systems (virtual machines) using hierarchical fixed-priority preemptive scheduling, without the requirement of kernel modifications.
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