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Lock-Based Resource Sharing in Real-Time Multiprocessor Platforms
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.ORCID iD: 0000-0002-0474-2904
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Embedded systems are typically resource constrained, i.e., resources such as processors, I/O devices, shared buffers or shared memory can be limited for tasks in the system. Therefore, techniques that enable an efficient usage of such resources are of great importance.

In the industry, typically large and complex software systems are divided into smaller parts (applications) where each part is developed independently. Migration towards multiprocessor platforms has become inevitable from an industrial perspective. Due to such migration and to efficient use of system resources, these applications eventually may be integrated on a shared multiprocessor platform. In order to facilitate the integration phase of the applications on a shared platform, the timing and resource requirements of each application can be provided in an interface when the application is developed. The system integrator can benefit from such provided information in the interface of each application to ease the integration process. In this thesis, we have provided the resource and timing requirements of each application in their interfaces for applications that may need several processors to be allocated on when they are developed.

Although many scheduling techniques have been studied for multiprocessor systems, these techniques are usually based on the assumption that tasks are independent, i.e. do not share resources other than the processors. This assumption is typically not true. In this thesis, we provide an extension to such systems to handle sharing of resources other than processor among tasks. Two traditional approaches exist for multiprocessor systems to schedule tasks on processors. A recent scheduling approach for multiprocessors has combined the two traditional approaches and achieved a hybrid more efficient approach compared to the two previous one. Due to the complex nature of this scheduling approach the conventional approaches for resource sharing could not be used straight forwardly. In this thesis, we have modified resource sharing approaches such that they can be used in such hybrid scheduling systems. A second concern is that enabling resource sharing in the systems can cause unpredictable delays and variations in response time of tasks which can degrade system performance. Therefore, it is of great significance to improve the resource handling techniques to reduce the effect of imposed delays caused by resource sharing in a multiprocessor platform. In this thesis we have proposed alternative techniques for resource handling that can improve system performance for special setups.

Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2014.
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 189
National Category
Computer Science
Research subject
Computer Science
Identifiers
URN: urn:nbn:se:mdh:diva-26532ISBN: 978-91-7485-178-6 (print)OAI: oai:DiVA.org:mdh-26532DiVA: diva2:762492
Presentation
2014-12-11, Lambda, Mälardalens högskola, Västerås, 09:15 (English)
Opponent
Supervisors
Available from: 2014-11-12 Created: 2014-11-11 Last updated: 2014-12-03Bibliographically approved
List of papers
1. Resource Sharing under Multiprocessor Semi-Partitioned Scheduling
Open this publication in new window or tab >>Resource Sharing under Multiprocessor Semi-Partitioned Scheduling
2012 (English)In: 18th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA'12), 2012, 290-299 p.Conference paper, Published paper (Refereed)
Abstract [en]

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.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-17295 (URN)10.1109/RTCSA.2012.25 (DOI)2-s2.0-84869032347 (Scopus ID)978-1-4673-3017-6 (ISBN)
Conference
Embedded and Real-Time Computing Systems and Applications (RTCSA), 2012 IEEE 18th International Conference, 19-22 Aug. 2012
Available from: 2012-12-20 Created: 2012-12-20 Last updated: 2017-11-06Bibliographically approved
2. Integrating independently developed real-time applications on a shared multi-core architecture
Open this publication in new window or tab >>Integrating independently developed real-time applications on a shared multi-core architecture
2013 (English)In: ACM SIGBED Review, v. 10, n. 3, 2013, 49-56 p.Conference paper, Published paper (Refereed)
Abstract [en]

The shift towards multi-core platforms has become inevitable from an industry perspective, therefore proper techniques are needed to deal with challenges related to this migration from single core architectures to a multi-core architecture. One of the main concerns for the system developers in this context is the migration of legacy real-time systems to multi-core architectures. To address this concern and to simplify migration, independently developed subsystems are abstracted with an interface, such that when working with multiple independently-developed subsystems to be integrated on a shared platform, one does not need to be aware of information or policies used in other subsystems in order to determine subsystem-level schedulability. Instead schedulability can be checked through their interfaces at the time of integration on a shared multi-core architecture. In this paper we propose a solution for the case where some of the independently-developed subsystems are distributed over more than one processor and we propose an approach to generate interfaces of subsystems that may share mutually exclusive resources.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-17391 (URN)10.1145/2544350.2544356 (DOI)
External cooperation:
Conference
5th International Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS'12),San Juan, Puerto Rico, December 4, 2012
Available from: 2012-12-20 Created: 2012-12-20 Last updated: 2016-08-26Bibliographically approved
3. Flexible spin-lock model for resource sharing in multiprocessor real-time systems
Open this publication in new window or tab >>Flexible spin-lock model for resource sharing in multiprocessor real-time systems
2014 (English)In: Proc. IEEE Int. Symp. Ind. Embedded Syst., SIES, 2014, 41-51 p.Conference paper, Published paper (Refereed)
Abstract [en]

Various approaches can be utilized upon resource locking for mutually exclusive resource access in multiprocessor platforms. So far two conventional approaches exist for dealing with tasks that are blocked on a global resource in a multi-processor platform. Either the blocked task performs a busy wait, i.e. spins, at the highest priority level until the resource is released, or it is suspended. Although both approaches provide mutually exclusive access to resources, they can introduce long blocking delays to tasks, which may be unacceptable for many industrial applications. In this paper, we propose a general spin-based model for resource sharing in multiprocessor platforms in which the priority of the blocked tasks during spinning can be selected arbitrarily. Moreover, we provide the analysis for two selected spin-lock priorities and we show by means of a general comparison as well as specific examples that these solutions may provide a better performance for higher priority tasks.

Series
Proceedings of the 9th IEEE International Symposium on Industrial Embedded Systems, SIES 2014
Keyword
Locks (fasteners), Real time systems, Access to resources, Better performance, Conventional approach, Global resources, Multi-processor platforms, Resource access, Resource locking, Resource sharing, Multiprocessing systems
National Category
Computer and Information Science
Identifiers
urn:nbn:se:mdh:diva-25907 (URN)10.1109/SIES.2014.6871185 (DOI)000345746200007 ()2-s2.0-84906688738 (Scopus ID)9781479940233 (ISBN)
Conference
9th IEEE International Symposium on Industrial Embedded Systems, SIES 2014, 18 June 2014 through 20 June 2014, Pisa
Available from: 2014-09-12 Created: 2014-09-12 Last updated: 2017-11-06Bibliographically approved
4. Per Processor Spin-Lock Priority for Partitioned Multiprocessor Real-Time Systems
Open this publication in new window or tab >>Per Processor Spin-Lock Priority for Partitioned Multiprocessor Real-Time Systems
2014 (English)Report (Other academic)
Abstract [en]

Two traditional approaches exist for a task that is blocked on a global resource; a task either performs a non-preemptive busy wait, i.e., spins, or suspends and releases the processor. Previously, we have shown that both approaches can be viewed as spinning either at the highest priority HP or at the lowest priority on the processor LP, respectively. Based on this view, previously we have generalized a task's blocking behavioral model, as spinning at any arbitrary priority level. In this paper, we focus on a particular class of spin-lock protocols from the introduced flexible spin-lock model where spinning is performed at a priority equal to or higher than the highest local ceiling of the global resources accessed on a processor referred to as CP spin-lock approach. In this paper, we assume that all tasks of a specific processor are spinning on the same priority level. Given this class and assumption, we show that there exists a spin-lock protocol in this range that dominates the classic spin-lock protocol which tasks spin on highest priority level (HP). However we show that this new approach is incomparable with the CP spin-lock approach. Moreover, we show that there may exist an intermediate spin-lock approach between the priority used by CP spin-lock approach and the new introduced spin-lock approach that can make a task set schedulable when those two cannot. We provide an extensive evaluation results comparing the HP, CP and the new proposed approach.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2014
National Category
Computer Science
Identifiers
urn:nbn:se:mdh:diva-26523 (URN)MDH-MRTC-294/2014-1-SE (ISRN)
Available from: 2014-11-11 Created: 2014-11-11 Last updated: 2014-11-12Bibliographically approved

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