| 201. |
- Khalilzad, Nima, et al.
(författare)
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Bandwidth Adaptation in Hierarchical Scheduling Using Fuzzy Controllers
- 2012
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Ingår i: 7th IEEE International Symposium on Industrial Embedded Systems, SIES 2012 - Conference Proceedings. - : IEEE Press. - 9781467326841 ; , s. 148-157
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Konferensbidrag (refereegranskat)abstract
- In our previous work, we have introduced an adaptive hierarchical scheduling framework as a solution for composing dynamic real-time systems, i.e., systems where the CPU demand of their tasks are subjected to unknown and potentially drastic changes during run-time. The framework uses the PI controller which periodically adapts the system to the current load situation. The conventional PI controller despite simplicity and low CPU overhead, provides acceptable performance. However, increasing the pressure on the controller e.g, with an application consisting of multiple tasks with drastically oscillating execution times, degrades the performance of the PI controller. Therefore, in this paper we modify the structure of our adaptive framework by replacing the PI controller with a fuzzy controller to achieve better performance. Furthermore, we conduct a simulation based case study in which we compose dynamic tasks such as video decoder tasks with a set of static tasks into a single system, and we show that the new fuzzy controller outperforms our previous PI controller.
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| 202. |
- Khalilzad, Nima Moghaddami, et al.
(författare)
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Towards adaptive hierarchical scheduling of overloaded real-time systems
- 2011
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Ingår i: SIES 2011 - 6th IEEE International Symposium on Industrial Embedded Systems, Conference Proceedings. - 9781612848204 ; , s. 39-42
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Konferensbidrag (refereegranskat)abstract
- In a hierarchical scheduling framework, a resource can be shared among modules with different criticality levels. In our recently introduced adaptive hierarchical scheduling framework, modules receive a dynamic portion of the CPU during run-time. While providing temporal isolation is one of the main advantages of hierarchical scheduling, in an adaptive framework, for example when the CPU is overloaded, the higher priority modules can violate timing guarantees of the lower priority modules. However, the priorities of modules are assigned based on parameters other than the module criticality levels. For example the priority is often assigned according to periods and deadlines of tasks to increase the CPU utilization assuming static systems, i.e. modules parameters do not change during runtime. In an overload situation the high criticality modules should be superior to the low criticality modules in receiving resources. In this paper, extending our adaptive framework, we propose two techniques for controlling the CPU distribution among modules in an overload situation. We are taking another step towards having a complete adaptive hierarchical scheduling framework by incorporating an overload controller into our framework.
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| 203. |
- Khalilzad, Nima, et al.
(författare)
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On Component-Based Software Development for Multiprocessor Real-Time Systems
- 2015
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Ingår i: Proceedings - IEEE 21st International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2015. - 9781467378550 ; , s. 132-140
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Konferensbidrag (refereegranskat)abstract
- Component-based software development providesa modular approach to develop complex software systems. In the context of real-time systems, it is desirable to abstract the timing properties of software components using an interface foreach component. The timing properties of the whole system, composed of multiple components, is studied using the component interfaces. In this paper we focus on periodic interface models. In the case of components developed for single processor platforms, for examining the system schedulability, the interfaces can be regarded as periodic tasks. Thus, making it possible to use the conventional schedulability analyses for the system level schedulability test. In the case of components developed formultiprocessors, since interfaces may have utilization larger than 100 % of a single processor, it is not possible to directly use the component interfaces for the system schedulability test. There-fore, the interfaces have to be decomposed before performing thesystem level schedulability test. In this paper, we target the special case of partitioned EDF for scheduling the components integrated on a multiprocessor. Therefore, the system level schedulability test is equivalent to finding a feasible allocation of component interfaces on the multiprocessor. We propose two algorithms for allocating the multiprocessor periodic interfaces. In addition, we propose anorthogonal approach for developing component-based real-timesystems on multiprocessors in which components with utilizationmore than 100 % of a single processor are divided into smaller subcomponents before abstracting their interfaces. We show, through extensive evaluations, that our alternative approach significantly reduces the interface overhead.
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| 204. |
- Khalilzad, Nima, et al.
(författare)
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Towards Adaptive Resource Reservations for Component-Based Distributed Real-Time Systems
- 2015
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Ingår i: ACM SIGBED Review - Special Issue on the 7th Workshop on Adaptive and Reconfigurable Embedded Systems (APRES 2015). - : Association for Computing Machinery (ACM). ; , s. 24-27
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Konferensbidrag (refereegranskat)abstract
- —In this paper we present our ongoing work on developing a framework supporting adaptive resource reservations targeting component-based distributed real-time systems. The components may be spread over different resources in a distributed system. The proposed framework utilizes a reservationbased scheduling technique in which the sizes of reservations are adjusted during run-time to deal with dynamic resource demands of the software components. We present our modeling approach, we describe design options made and we present corresponding challenges.
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| 205. |
- Khalilzad, Nima, et al.
(författare)
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Towards Energy-Aware Placement of Real-Time Virtual Machines in a Cloud Data Center
- 2015
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Ingår i: Proceedings - 2015 IEEE 17th International Conference on High Performance Computing and Communications, 2015 IEEE 7th International Symposium on Cyberspace Safety and Security and 2015 IEEE 12th International Conference on Embedded Software and Systems, HPCC-CSS-ICESS 2015. - 9781479989362 ; , s. 1657-1662
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Konferensbidrag (refereegranskat)abstract
- Cloud computing is an evolving paradigm which is becoming an adoptable technology for a variety of applications. However, cloud infrastructures must be able to fulfill application requirements before adopting cloud solutions. Cloud infrastructure providers communicate the characteristics of their services to their customers through Service Level Agreements (SLA). In order for a real-time application to be able to use cloud technology, cloud infrastructure providers have to be able to provide timing guarantees in the SLAs. In this paper, we present our ongoing work regarding a cloud solution in which periodic tasks are provided as a service in the Software as a Service (SaS) model. Tasks belonging to a certain application are mapped in a Virtual Machine (VM). We also study the problem of VMplacement on a cloud infrastructure. We propose a placement mechanism which minimizes the energy consumption of the data center by consolidating VMs in a minimum number of servers while respecting the timing requirement of virtual machines.
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| 206. |
- Kienle, Holger, et al.
(författare)
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System-specific static code analyses : a case study in the complex embedded systems domain
- 2012
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Ingår i: Software quality journal. - : Springer Science and Business Media LLC. - 0963-9314 .- 1573-1367. ; 20:2, s. 337-367
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we are exploring the approach to utilize system-specific static analyses of code with the goal to improve software quality forspecific software systems. Specialized analyses, tailored for a particular system, make it possible to take advantage of system/domainknowledge that is not available to more generic analyses. Furthermore, analyses can be selected and/or developed in order to best meet the challenges and specific issues of the system at hand. As a result, such analyses can be used as a complement to more generic code analysistools because they are likely to have a better impact on (business) concerns such as improving certain software quality attributes and reducing certain classes of failures. We present a case study of a large, industrial embedded system, giving examples of what kinds of analyses could be realized and demonstrate the feasibility of implementing such analyses. We synthesize lessons learned based on our case study and provide recommendations on how to realize system-specific analyses and how to get them adopted by industry.
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| 207. |
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| 208. |
- Kraft, Johan, et al.
(författare)
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Continuous Constant-Memory Monitoring of Embedded Software Timing
- 2011
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Ingår i: 2nd International Workshop on Analysis Tools and Methodologies for Embedded and Real-time Systems (WATERS'11), satellite workshop of EUROMICRO Conference on Real-Time Systems (ECRTS'11).
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Konferensbidrag (refereegranskat)abstract
- A method is presented for generating statistical models of timing data continuously over very long monitoring sessions. This method is intended for memory-efficient runtime modeling of timing properties in embedded software systems, such as execution times or inter-arrival times, but is a quite generic method that should be applicable for other purposes and domains as well. Specifically, we intend to use this method as a component in automatic generation of simulation models for probabilistic timing analysis of complex embedded software systems. Given a stream of data as input, this method gradually builds up a statistical model capturing the approximate distribution of the data. The method uses a modest and fixed amount of on-target RAM, decided by the desired accuracy of the model, and allows for long monitoring sessions covering billions of data points. The paper presents the motivation, algorithm, a prototype implementation and evaluation using real execution time data from an ARM7 microcontroller.
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| 209. |
- Kraft, Johan, et al.
(författare)
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Software Maintenance Research in the PROGRESS Project for Predictable Embedded Software Systems
- 2011
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Ingår i: 15th European Conference on Software Maintenance and Reengineering (CSMR'11). - Los Alamitos : IEEE Computer Society. - 9780769543437 ; , s. 335-338
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Konferensbidrag (refereegranskat)abstract
- PROGRESS is a project and strategic research centre at Malardalen University in Sweden that is funded for 2006-2010 by the Swedish Foundation for Strategic Research (SSF). PROGRESS research targets embedded software in the vehicular, automation, and telecom domains, focusing on the areas of component technology, verification and analysis for predictability, predictable execution, as well as reuse and maintenance of legacy embedded software. We first describe the funding, organization and research areas of PROGRESS, and then give several examples of PROGRESS research that addresses maintenance of legacy embedded software with the goal to improve program comprehension, quality assurance, and debugging. Specifically, we describe research in tracing and trace visualization, impact analysis of temporal behavior, slicing, and system-specific static analyses.
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| 210. |
- Lager, Anders, et al.
(författare)
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A Scalable Heuristic for Mission Planning of Mobile Robot Teams
- 2023
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Ingår i: IFAC-PapersOnLine. - : Elsevier B.V.. - 9781713872344 ; , s. 7865-7872
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Konferensbidrag (refereegranskat)abstract
- In this work, we investigate a task planning problem for assigning and planning a mobile robot team to jointly perform a kitting application with alternative task locations. To this end, the application is modeled as a Robot Task Scheduling Graph and the planning problem is modeled as a Mixed Integer Linear Program (MILP). We propose a heuristic approach to solve the problem with a practically useful performance in terms of scalability and computation time. The experimental evaluation shows that our heuristic approach is able to find efficient plans, in comparison with both optimal and non-optimal MILP solutions, in a fraction of the planning time.
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