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An optimal spin-lock priority assignment algorithm for real-time multi-core systems
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.ORCID iD: 0000-0002-0474-2904
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.ORCID iD: 0000-0002-1687-930X
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Technische Universiteit Eindhoven, Eindhoven, Netherlands.ORCID iD: 0000-0001-6234-5117
Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.ORCID iD: 0000-0001-6132-7945
2017 (English)In: The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17, 2017, 8046310Conference paper, Published paper (Refereed)
Abstract [en]

Support for exclusive access to shared (global) resources is instrumental in the context of embedded real-time multi-core systems, and mechanisms for achieving such access must be deterministic and efficient. There exist two traditional approaches for multiprocessors when a task requests a global resource that is locked by a task on a remote core: a spin-based approach, i.e. non-preemptive busy waiting for the resource to become available, and a suspension-based approach, i.e. the task relinquishes the processor. A suspension-based approach can be viewed as a spin-based approach where the lowest priority on a core is used during spinning, similar to a non-preemptive spin-based approach where the highest priority on a core is used. By taking such a view, we previously provided a general model for spinning, where any arbitrary priority can be used for spinning, i.e. from the lowest to the highest priority on a core. Targeting partitioned fixed-priority preemptive scheduled multiprocessors and spin-based approaches that use a fixed priority for spinning per core for all tasks, we aim at increasing the schedulability of multiprocessor systems by using the spin-lock priority per core as parameter. In this paper, we present (i) a generalization of the traditional worst-case response-time analysis for non-preemptive spin-based approaches addressing an arbitrary but fixed spin-lock priority per core, (ii) an optimal spin-lock priority assignment (OSPA) algorithm per core, i.e. an algorithm that will find a fixed spin-lock priority per core that will make the system schedulable, whenever such an assignment exists and, (iii) comparative evaluations of the OSPA algorithm with the spin-based and suspension-based approaches where OSPA showed up to 38% improvement compared to both approaches.

Place, publisher, year, edition, pages
2017. 8046310
National Category
Computer Systems
Identifiers
URN: urn:nbn:se:mdh:diva-37055DOI: 10.1109/RTCSA.2017.8046310OAI: oai:DiVA.org:mdh-37055DiVA: diva2:1154469
Conference
The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17, 16 Aug 2017, Hsinchu, Taiwan
Projects
PRESS - Predictable Embedded Software SystemsDPAC - Dependable Platforms for Autonomous systems and Control
Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2017-11-16Bibliographically 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, Sara ZargariBehnam, MorisJ. Bril, ReinderNolte, Thomas

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