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Per Processor Spin-Lock Priority for Partitioned Multiprocessor Real-Time Systems
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. (Complex Real-Time Systems)ORCID iD: 0000-0002-0474-2904
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. (Complex Real-Time Systems)ORCID iD: 0000-0002-1687-930X
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. (Complex Real-Time Systems)ORCID iD: 0000-0001-6234-5117
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. (Complex Real-Time Systems)ORCID iD: 0000-0001-6132-7945
(English)In: Leibniz Transactions on Embedded Systems, ISSN 2199-2002Article in journal (Other academic) Accepted
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.

National Category
Computer Science
Identifiers
URN: urn:nbn:se:mdh:diva-37183OAI: oai:DiVA.org:mdh-37183DiVA: diva2:1154506
Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2017-11-06Bibliographically approved
In thesis
1. Lock-Based Resource Sharing for Real-Time Multiprocessors
Open this publication in new window or tab >>Lock-Based Resource Sharing for Real-Time Multiprocessors
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Embedded systems are widely used in the industry and are typically resource constrained, i.e., resources such as processors, I/O devices, shared buffers or shared memory might be limited in the system. Hence, techniques that can enable an efficient usage of processor bandwidths in such systems are of great importance. Locked-based resource sharing protocols are proposed as a solution to overcome resource limitation by allowing the available resources in the system to be safely shared. In recent years, due to a dramatic enhancement in the functionality of systems, a shift from single-core processors to multi-core processors has become inevitable from an industrial perspective to tackle the raised challenges due to increased system complexity. However, the resource sharing protocols are not fully mature for multi-core processors. The two classical multi-core processor resource sharing protocols, spin-based and suspension-based protocols, although providing mutually exclusive access to resources, can introduce long blocking delays to tasks, which may be unacceptable for many industrial applications. In this thesis we enhance the performance of resource sharing protocols for partitioned scheduling, which is the de-facto scheduling standard for industrial real-time multi-core processor systems such as in AUTOSAR, in terms of timing and memory requirements.

 

A new scheduling approach uses a resource efficient hybrid approach combining both partitioned and global scheduling where the partitioned scheduling is used to schedule the major number of tasks in the system. In such a scheduling approach applications with critical task sets use partitioned scheduling to achieve higher level of predictability. Then the unused bandwidth on each core that is remained from partitioning is used to schedule less critical task sets using global scheduling to achieve higher system utilization. These scheduling schema however lacks a proper resource sharing protocol since the existing protocols designed for partitioned and global scheduling cannot be directly applied due to the complex hybrid structure of these scheduling frameworks. In this thesis we propose a resource sharing solution for such a complex structure. Further, we provide the blocking bounds incurred to tasks under the proposed protocols and enhance the schedulability analysis, which is an essential requirement for real-time systems, with the provided blocking bounds.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2017
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 247
National Category
Embedded Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:mdh:diva-37215 (URN)978-91-7485-361-2 (ISBN)
Public defence
2017-12-19, Kappa, Mälardalens högskola, Västerås, 13:30 (English)
Opponent
Supervisors
Available from: 2017-11-07 Created: 2017-11-06 Last updated: 2017-11-09Bibliographically approved

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Afshar, SaraBehnam, MorisJ. Bril, ReinderNolte, Thomas

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