| 1. |
- 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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| 2. |
- Afshar, Sara, et al.
(author)
-
Resource Sharing under Multiprocessor Semi-Partitioned Scheduling
- 2012
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In: 18th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA'12). - : IEEE. - 9781467330176 - 9780769548241 ; , s. 290-299
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Conference paper (peer-reviewed)abstract
- Semi-partitioned scheduling has become the subject of recent interest for multiprocessors due to better utilization results, compared to conventional global and partitioned scheduling algorithms. Under semi-partitioned scheduling, a major group of tasks are assigned to fixed processors while a low number of tasks are allocated to more than one processor. Various task assigning techniques have recently been proposed in a semi-partitioned environment. However, a synchronization mechanism for resource sharing among tasks in semi-partitioned scheduling has not yet been investigated. In this paper we propose and evaluate two methods for handling resource sharing under semi-partitioned scheduling in multiprocessor platforms. The main challenge addressed in this paper is to serve the resource requests of tasks that are assigned to different processors.
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| 3. |
- Afshar, Sara, et al.
(author)
-
Towards Resource Sharing under Multiprocessor Semi-Partitioned Scheduling
- 2012
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In: 7th IEEE International Symposium on Industrial Embedded Systems (SIES'12). - : IEEE. - 9781467326834 - 9781467326858 ; , s. 315-318
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Conference paper (peer-reviewed)abstract
- Semi-partitioned scheduling has been the subject of recent interest, compared with conventional global and partitioned scheduling algorithms for multiprocessors, due to better utilization results. In semi-partitioned scheduling most tasks are assigned to fixed processors while a low number of tasks are split up and allocated to different processors. Various techniques have recently been proposed to assign tasks in a semi-partitioned environment. However, an appropriate resource sharing mechanism for handling the resource requests between tasks in semi-partitioned scheduling has not yet been investigated. In this paper we propose two methods for handling resource sharing under semi-partitioned scheduling in multiprocessor platforms. The main challenge is to handle the resource requests of tasks that are split over multiple processors.
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| 4. |
- Behnam, Moris, et al.
(author)
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Towards an efficient approach for resource sharing in real-time multiprocessor systems
- 2011
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In: 2011 6th IEEE International Symposium on Industrial and Embedded Systems. - Västerås : IEEE. - 9781612848181 - 9781612848198 ; , s. 99-102, s. 99-102
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Conference paper (peer-reviewed)abstract
- Supporting resource sharing in multiprocessor architectures is one of the major problems that limit the potential performance benefits of using such architectures for real-time systems. Many approaches and algorithms have been proposed to support resource sharing, however, most of them impose either high blocking times on tasks or require a large memory allocation. In this paper we investigate the possibility of combining the lock-based approaches and wait-free approaches (using multiple buffers) in order to decrease both the blocking times that may affect the schedulability of tasks and the required memory. To achieve this, we propose a solution based on evaluating the maximum allowed blocking time on each task according to the schedulability analysis, and then find the minimum memory allocation for each resource that limits the blocking times on tasks to be less than the maximum allowed blocking times.
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| 5. |
- Nemati, Farhang, et al.
(author)
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A Flexible Tool for Evaluating Scheduling, Synchronization and Partitioning Algorithms on Multiprocessors
- 2010
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In: 2010 IEEE CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION (ETFA). - 9781424468508 ; , s. 1-4
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Conference paper (peer-reviewed)abstract
- Multi-core platforms seem to be the way towards increasing performance of processors. Single-chip multiprocessors (multi-cores) are today the dominating technology for desktop computing. As the multi-cores are becoming the defacto processors, the need for new scheduling and resource sharing protocols has arisen.There are two major types of scheduling under multiprocessor/multi-core platforms. Global scheduling, under which migration of tasks among processors is allowed, and partitioned scheduling under which tasks are allocated onto processors and task migration is not allowed. The partitioned scheduling protocols suffer from the problem of partitioning tasks among processors/cores, which is a bin-packing problem. Heuristic algorithms have been developed for partitioning a task set on multiprocessor platforms.However, taking such technology to an industrial setting, it needs to be evaluated such that appropriate scheduling, synchronization and partitioning algorithms are selected.In this paper we present our work on a tool for investigation and evaluation of different approaches to scheduling, synchronization and partitioning on multi-core platforms. Our tool allows for comparison of different approaches with respect to a number of parameters such as number of schedulable systems and number of processors required for scheduling.The output of the tool includes a set of information and graphs to facilitate evaluation and comparison of different approaches.
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| 6. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(author)
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An Investigation of Synchronization under Multiprocessors Hierarchical Scheduling
- 2009
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In: Proceedings of the Work-In-Progress (WIP) session of the 21st Euromicro Conference on Real-Time Systems (ECRTS'09).
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Conference paper (peer-reviewed)abstract
- In the multi-core and multiprocessor research community, considerable work has been done on real-time multiprocessor scheduling algorithms where it is assumed the tasks are independent. However in practice a typical real-time system includes tasks that share resources. On the other hand, synchronization in the multiprocessor context has not received enough attention.In this paper we propose an extension to multiprocessor hierarchical scheduling to support resource sharing. We extend the scheduling framework with an existing synchronization protocol for global scheduling in multi-core systems.
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| 7. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(author)
-
Efficiently Migrating Real-Time Systems to Multi-Cores
- 2009
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In: 2009 IEEE Conference on Emerging Technologies & Factory Automation. - : IEEE. - 9781424427284 - 9781424427277 ; , s. 1205-1212
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Conference paper (peer-reviewed)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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| 8. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(author)
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Independently-Developed Real-Time Systems on Multi-Cores with Shared Resources
- 2011
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In: 2011 23rd Euromicro Conference on Real-Time Systems. - Porto, Portugal : IEEE. - 9781457706431 ; , s. 251-261, s. 251-261
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Conference paper (peer-reviewed)abstract
- In this paper we propose a synchronization protocol for resource sharing among independently-developed real-time systems on multi-coreplatforms. The systems may use different scheduling policies and they may have their own local priority settings. Each system is allocated on a dedicated processor (core). In the proposed synchronization protocol, each system is abstracted by an interface which abstracts the information needed for supporting global resources. The protocol facilitates the composability of various real-time systems with different scheduling and priority settings on a multi-core platform. We have performed experimental evaluations and compared the performance of our proposed protocol (MSOS) against the two existing synchronization protocols MPCP and FMLP. The results show that the new synchronization protocol enables composability without any significant loss of performance. In fact, in most cases the new protocol performs better than at least one of the other two synchronization protocols. Hence, we believe that the proposed protocol is a viable solution for synchronization among independently-developedreal-time systems executing on a multi-core platform.
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| 9. |
- Nemati, Farhang, et al.
(author)
-
Independently-developed Systems on Multi-cores with Shared Resources
- 2010
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In: 3rd Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS'10) in conjunction with the 31th IEEE International Real-Time Systems Symposium (RTSS'10). - San Diego, CA, USA.
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Conference paper (peer-reviewed)abstract
- In this paper we propose a synchronization protocol for resource sharing among independently-developed real-time systems on multi-core platforms. The systems may use different scheduling policies and they may have arbitrary priority settings. When using this synchronization protocol each processor is abstracted by an interface which consists of a set of requirements. A requirement depends only on the worst-case time the processor may wait for resources, i.e., the maximum number of times that the resources can be blocked by other processors. We have derived schedulability conditions for each processor and based on the analysis we extract the interface of the processor. In this paper, we focus on the cases when each system is allocated on a dedicated processor.
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| 10. |
- Nemati, Farhang, Senior Lecturer, 1975-, et al.
(author)
-
Investigation of Implementing a Synchronization Protocol under Multiprocessors Hierarchical Scheduling
- 2009
-
In: 2009 IEEE Conference on Emerging Technologies & Factory Automation. - : IEEE. - 9781424427277 - 9781424427284
-
Conference paper (peer-reviewed)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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