| 21. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(författare)
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Efficiently Migrating Real-Time Systems to Multi-Cores
- 2009
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Ingår i: 2009 IEEE Conference on Emerging Technologies & Factory Automation. - : IEEE. - 9781424427284 - 9781424427277 ; , s. 1205-1212
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Konferensbidrag (refereegranskat)abstract
- Power consumption and thermal problems limit a further increase of speed in single-core processors. Multi-core architectures have therefore received significant interest. However, a shift to multi-core processors is a big challenge for developers of embedded real-time systems, especially considering existing “legacy” systems which have been developed with uniprocessor assumptions. These systems have been developed and maintained by many developers over many years, and cannot easily be replaced due to the huge development investments they represent. An important issue while migrating to multi-cores is how to distribute tasks among cores to increase performance offered by the multi-core platform. In this paper we propose a partitioning algorithm to efficiently distribute legacy system tasks along with newly developed ones onto different cores. The target of the partitioning is increasing system performance while ensuring correctness.
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| 22. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(författare)
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Investigation of Implementing a Synchronization Protocol under Multiprocessors Hierarchical Scheduling
- 2009
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Ingår i: 2009 IEEE Conference on Emerging Technologies & Factory Automation. - : IEEE. - 9781424427277 - 9781424427284
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Konferensbidrag (refereegranskat)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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| 23. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(författare)
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Multiprocessor Synchronization and Hierarchical Scheduling
- 2009
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Ingår i: 2009 International Conference on Parallel Processing Workshops. - : IEEE. - 9781424449231 - 9780769538037 ; , s. 58-64
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Konferensbidrag (refereegranskat)abstract
- Multi-core architectures have received significant interest as thermal and power consumption problems limit further increase of speed in single-cores. In the multi-core research community a considerable amount of work has been done on real-time multi-core scheduling algorithms where it is assumed tasks are independent. However, synchronization of dependent tasks executing on multi-cores has not received as much attention, even though typical real-time systems in practice include tasks that share resources.In this paper we propose a synchronization protocol for hierarchically scheduledmulti-core systems, and we present a comparison between the presented protocol and existing multi-core synchronization protocols. The presented protocol groups dependent tasks that directly or indirectly share mutually exclusive resources into independent components. Within a component dependent tasks use classical uniprocessor synchronization protocols, such as the Stack-based Resource allocation Protocol. The components are then scheduled on the cores by a global scheduler.There are two major approaches for scheduling multicore: partitioned and global scheduling. While most existing multi-core synchronization protocols support only one category, the protocol presented in this paper is developed to handle both scheduling approaches. The presented approach is developed to allow for co-execution of existing legacy real-time applications along with new applications, i.e., a legacy application is put into one or more components preserving its own (original) scheduling and synchronization protocols.
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| 24. |
- Nolte, Thomas, et al.
(författare)
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A Synchronization Protocol for Temporal Isolation of Software Components in Vehicular Systems
- 2009
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Ingår i: IEEE Transactions on Industrial Informatics. - 1551-3203 .- 1941-0050. ; 5:4, s. 375-387
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Tidskriftsartikel (refereegranskat)abstract
- We present a method that allows for integration of individually developed functions of software components into a predictable real-time system. The method has been designed to provide a lightweight mechanism that gives temporal firewalls between functions, preventing unpredictable side effects during function integration. The method maps well to the AUTOSAR (AUTomotive Open System ARchitecture) software component model and can thus be used to facilitate seamless and predictable integration and isolation of AUTOSAR components that have been developed by different manufacturers. Specifically, this paper presents a protocol for synchronization in a hierarchical real-time scheduling framework. Using our protocol, a software component does not need to know, and is not dependent on, the timing behavior of software components belonging to other functions; even though they share mutually exclusive resources. In this paper, we also prove the correctness of our approach and evaluate its efficiency and cost in terms of system load in a vehicular context.
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| 25. |
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| 26. |
- Shin, Insik, et al.
(författare)
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On Optimal Hierarchical Resource Sharing in Open Environments
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a new perspective in the context of supporting logical resource sharing under hierarchical scheduling. Our work is motivated from a tradeoff between reducing resource holding times and reducing system load (i.e., the collective processor requirements to guarantee the schedulability of hierarchical scheduling frameworks). We formulate an optimization problem that determines the resource holding times of each individual tasks (and therefore those of subsystems) with the goal of minimizing the system load subject to the system's schedulability. We present efficient algorithms to find an optimal solution to the problem, and we prove their correctness.
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| 27. |
- Shin, Insik, et al.
(författare)
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Synthesis of Optimal Interfaces for Hierarchical Scheduling with Resources
- 2008
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Ingår i: Proceedings of the 29th IEEE International Real-Time Systems Symposium (RTSS08).. - 9780769534770 ; , s. 209-220
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Konferensbidrag (refereegranskat)abstract
- This paper presents algorithms that (1) facilitate system independent synthesis of timing-interfaces for subsystems and (2) system-level selection of interfaces to minimize CPU load. The results presented are developed for hierarchical fixed-priority scheduling of subsystems that may share logical recourses (i.e., semaphores). We show that the use of shared resources results in a tradeoff problem, where resource locking times can be traded for CPU allocation, complicating the problem of finding the optimal interface configuration subject to schedulability. This paper presents a methodology where such a tradeoff can be effectively explored. It first synthesizes a bounded set of interface-candidates for each subsystem, independently of the final system, such that the set contains the interface that minimizes system load for any given system. Then, integrating subsystems into a system, it finds the optimal selection of interfaces. Our algorithms have linear complexity to the number of tasks involved. Thus, our approach is highly suitable for adaptable and reconfigurable systems.
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| 28. |
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| 29. |
- Åsberg, Mikael, et al.
(författare)
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Towards Hierarchical Scheduling in AUTOSAR
- 2009
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Ingår i: 2009 IEEE Conference on Emerging Technologies & Factory Automation. - : IEEE. - 9781424427284 - 9781424427277
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Konferensbidrag (refereegranskat)abstract
- AUTOSAR [17] is a partnership between automotive manufactures and suppliers. It aims at standardizing the automotive software architecture and separating software and hardware. This approach makes software more independent, maintainable, reuseable, etc. Still there is much work to do in order for this standard to be usable. This paper focus on automotive software integration in AUTOSAR, with the use of hierarchical scheduling as an enabling technology. At this point, AUTOSARcomponents do not have any timing relation with its tasks [19, 20]. This causes an unpredictive runtime behavior which can only be analyzed and verified after integration phase. We will discuss how integration can be done in AUTOSAR, with runtime temporal isolation of components. This will enable schedulability analysis at the level of components rather than at the level of tasks.
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