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Publications (10 of 72) Show all publications
Balasubramanian, S. M., Afshar, S., Gai, P., Behnam, M. & J. Bril, R. (2019). Practical challenges for FSLM. In: Proceedings - 2018 IEEE 24th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2018: . Paper presented at 24th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2018 (pp. 238-239). Institute of Electrical and Electronics Engineers Inc., Article ID 8607257.
Open this publication in new window or tab >>Practical challenges for FSLM
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2019 (English)In: Proceedings - 2018 IEEE 24th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2018, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 238-239, article id 8607257Conference paper, Published paper (Refereed)
Abstract [en]

The flexible spin-lock model (FSLM) unifies suspension-based and spin-based resource access protocols for partitioned fixed-priority preemptive scheduling based real-time multi-core platforms. Recent work has been done in defining the protocol for FSLM, providing schedulability analysis, and investigating the practical consequences of the theoretical model. FSLM complies to the AUTOSAR standard for the automotive industry, and prototype implementations of FSLM in the OSEK/VDX-complaint Erika Enterprise Real-Time Operating System have been realized. In this paper, we briefly describe some practical challenges to improve efficiency and generality. 

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-42811 (URN)10.1109/RTCSA.2018.00039 (DOI)000458980300030 ()2-s2.0-85061834140 (Scopus ID)9781538677599 (ISBN)
Conference
24th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2018
Available from: 2019-02-28 Created: 2019-02-28 Last updated: 2019-03-07Bibliographically approved
Cao, J., Ashjaei, S. M., Cuijpers, P. J. .., J. Bril, R. & Lukkien, J. (2018). An Independent yet Efficient Analysis of Bandwidth Reservation for Credit-based Shaping in Ethernet TSN. In: International Workshop on Factory Communication Systems WFCS'18: . Paper presented at International Workshop on Factory Communication Systems WFCS'18, 13 Jun 2018, Imperia, Italy (pp. 1-10). Imperia, Italy
Open this publication in new window or tab >>An Independent yet Efficient Analysis of Bandwidth Reservation for Credit-based Shaping in Ethernet TSN
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2018 (English)In: International Workshop on Factory Communication Systems WFCS'18, Imperia, Italy, 2018, p. 1-10Conference paper, Published paper (Refereed)
Abstract [en]

Ethernet TSN is an upcoming communication standard for industrial distributed embedded systems with high demands on bandwidth and traffic delay. In this paper, we present and prove an improved analysis to determine bandwidth reservations for credit based shapers in a single Ethernet TSN switch. We compare this new analysis, which is based on eligible intervals, to the state-of-the-art bandwidth reservation analysis based on busy periods through experiments. Despite its low complexity and the independence of the knowledge of the interfering traffic, the results show an improvement of efficiency, i.e., a decrease of the required bandwidth, for the new analysis.

Place, publisher, year, edition, pages
Imperia, Italy: , 2018
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-38966 (URN)10.1109/WFCS.2018.8402345 (DOI)000490863500009 ()2-s2.0-85050016783 (Scopus ID)978-1-5386-1066-4 (ISBN)
Conference
International Workshop on Factory Communication Systems WFCS'18, 13 Jun 2018, Imperia, Italy
Projects
Future factories in the Cloud
Available from: 2018-04-10 Created: 2018-04-10 Last updated: 2019-10-31Bibliographically approved
Hatvani, L., Afshar, S. Z. & J. Bril, R. (2018). Optimal Priority and Threshold Assignment for Fixed-priority Preemption Threshold Scheduling. Paper presented at 7th Embedded Operating Systems Workshop EWiLi'17, 06 Oct 2017, Seoul, South Korea. ACM SIGBED Review (1), 43-49
Open this publication in new window or tab >>Optimal Priority and Threshold Assignment for Fixed-priority Preemption Threshold Scheduling
2018 (English)In: ACM SIGBED Review, E-ISSN 1551-3688, no 1, p. 43-49Article in journal (Refereed) Published
Abstract [en]

Fixed-priority preemption-threshold scheduling (FPTS) is a generalization of fixed-priority preemptive scheduling (FPPS) and fixed-priority non-preemptive scheduling (FPNS). Since FPPS and FPNS are incomparable in terms of potential schedulability, FPTS has the advantage that it can schedule any task set schedulable by FPPS or FPNS and some that are not schedulable by either. FPTS is based on the idea that each task is assigned a priority and a preemption threshold. While tasks are admitted into the system according to their priorities, they can only be preempted by tasks that have priority higher than the preemption threshold.

This paper presents a new optimal priority and preemption threshold assignment (OPTA) algorithm for FPTS which in general outperforms the existing algorithms in terms of the size of the explored state-space and the total number of worst case response time calculations performed. The algorithm is based on back-tracking, i.e. it traverses the space of potential priorities and preemption thresholds, while pruning infeasible paths, and returns the first assignment deemed schedulable.

We present the evaluation results where we compare the complexity of the new algorithm with the existing one. We show that the new algorithm significantly reduces the time needed to find a solution. Through a comparative evaluation, we show the improvements that can be achieved in terms of schedulability ratio by our OPTA compared to a deadline monotonic priority assignment.

National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-37058 (URN)2-s2.0-84992364765 (Scopus ID)
Conference
7th Embedded Operating Systems Workshop EWiLi'17, 06 Oct 2017, Seoul, South Korea
Projects
PRESS - Predictable Embedded Software Systems
Available from: 2017-11-07 Created: 2017-11-07 Last updated: 2019-01-28Bibliographically approved
Afshar, S. Z., Behnam, M., J. Bril, R. & Nolte, T. (2017). An optimal spin-lock priority assignment algorithm for real-time multi-core systems. In: The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17: . Paper presented at The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17, 16 Aug 2017, Hsinchu, Taiwan. , Article ID 8046310.
Open this publication in new window or tab >>An optimal spin-lock priority assignment algorithm for real-time multi-core systems
2017 (English)In: The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17, 2017, article id 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.

National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-37055 (URN)10.1109/RTCSA.2017.8046310 (DOI)000425851000008 ()2-s2.0-85032735746 (Scopus ID)
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: 2018-03-15Bibliographically approved
J. Bril, R., Altmeyer, S., van den Heuvel, M. M. H., Davis, R. I. & Behnam, M. (2017). Fixed priority scheduling with pre-emption thresholds and cache-related pre-emption delays: integrated analysis and evaluation. Real-time systems, 53(4), 403-466
Open this publication in new window or tab >>Fixed priority scheduling with pre-emption thresholds and cache-related pre-emption delays: integrated analysis and evaluation
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2017 (English)In: Real-time systems, ISSN 0922-6443, E-ISSN 1573-1383, Vol. 53, no 4, p. 403-466Article in journal (Refereed) Published
Abstract [en]

Commercial off-the-shelf programmable platforms for real-time systems typically contain a cache to bridge the gap between the processor speed and main memory speed. Because cache-related pre-emption delays (CRPD) can have a significant influence on the computation times of tasks, CRPD have been integrated in the response time analysis for fixed-priority pre-emptive scheduling (FPPS). This paper presents CRPD aware response-time analysis of sporadic tasks with arbitrary deadlines for fixed-priority pre-emption threshold scheduling (FPTS), generalizing earlier work. The analysis is complemented by an optimal (pre-emption) threshold assignment algorithm, assuming the priorities of tasks are given. We further improve upon these results by presenting an algorithm that searches for a layout of tasks in memory that makes a task set schedulable. The paper includes an extensive comparative evaluation of the schedulability ratios of FPPS and FPTS, taking CRPD into account. The practical relevance of our work stems from FPTS support in AUTOSAR, a standardized development model for the automotive industry. [(This paper forms an extended version of Bril et al. (in Proceedings of 35th IEEE real-time systems symposium (RTSS), 2014). The main extensions are described in Sect. 1.2.].

National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-36009 (URN)10.1007/s11241-016-9266-z (DOI)000403073600001 ()2-s2.0-85011290627 (Scopus ID)
Available from: 2017-06-29 Created: 2017-06-29 Last updated: 2018-01-24Bibliographically approved
Balasubramanian, S., Afshar, S. Z., Gai, P., Behnam, M. & J. Bril, R. (2017). Incorporating implementation overheads in the analysis for the flexible spin-lock model. In: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY: . Paper presented at 43rd Annual Conference of the IEEE Industrial Electronics Society IECON 2017, 30 Oct 2017, Beijing, China (pp. 411-8418).
Open this publication in new window or tab >>Incorporating implementation overheads in the analysis for the flexible spin-lock model
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2017 (English)In: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY, 2017, p. 411-8418Conference paper, Published paper (Refereed)
Abstract [en]

The flexible spin-lock model (FSLM) unifies suspension-based and spin-based resource sharing protocols for partitioned fixed-priority preemptive scheduling based real-time multiprocessor platforms. Recent work has been done in defining the protocol for FSLM and providing a schedulability analysis without accounting for the implementation overheads. In this paper, we extend the analysis for FSLM with implementation overheads. Utilizing an initial implementation of FSLM in the OSEK/VDX-compliant Erika Enterprise RTOS on an Altera Nios II platform using 4 soft-core processors, we present an improved implementation. Given the design of the implementation, the overheads are characterized and incorporated in specific terms of the existing analysis. The paper also supplements the analysis with measurement results, enabling an analytical comparison of FSLM with the natively provided multiprocessor stack resource policy (MSRP), which may serve as a guideline for the choice of FSLM or MSRP for a specific application.

Series
IEEE Industrial Electronics Society
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-37057 (URN)10.1109/IECON.2017.8217477 (DOI)000427164808044 ()2-s2.0-85046623624 (Scopus ID)978-1-5386-1127-2 (ISBN)
Conference
43rd Annual Conference of the IEEE Industrial Electronics Society IECON 2017, 30 Oct 2017, Beijing, China
Projects
PRESS - Predictable Embedded Software SystemsDPAC - Dependable Platforms for Autonomous systems and Control
Available from: 2017-11-07 Created: 2017-11-07 Last updated: 2018-05-24Bibliographically approved
Afshar, S., Behnam, M., J. Bril, R. & Nolte, T. (2017). Per Processor Spin-Lock Priority for Partitioned Multiprocessor Real-Time Systems. Leibniz Transactions on Embedded Systems (2)
Open this publication in new window or tab >>Per Processor Spin-Lock Priority for Partitioned Multiprocessor Real-Time Systems
2017 (English)In: Leibniz Transactions on Embedded Systems, ISSN 2199-2002, no 2Article in journal (Other academic) Published
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 Sciences
Identifiers
urn:nbn:se:mdh:diva-37183 (URN)10.4230/LITES-v004-i002-a003 (DOI)
Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2018-12-14Bibliographically approved
Hatvani, L., J. Bril, R. & Altmeyer, S. (2017). Schedulability using native non-preemptive groups on an AUTOSAR/OSEK platform with caches. In: Proceedings of the 2017 Design, Automation and Test in Europe, DATE 2017: . Paper presented at 20th Design, Automation and Test in Europe, DATE 2017; SwissTech Convention CenterSwisstech, Lausanne; Switzerland; 27 March - 31 March 2017. (pp. 244-249). Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Schedulability using native non-preemptive groups on an AUTOSAR/OSEK platform with caches
2017 (English)In: Proceedings of the 2017 Design, Automation and Test in Europe, DATE 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 244-249Conference paper, Published paper (Refereed)
Abstract [en]

Fixed-priority preemption threshold scheduling (FPTS) is a limited preemptive scheduling scheme that generalizes both fixed-priority preemptive scheduling (FPPS) and fixed-priority non-preemptive scheduling (FPNS). By increasing the priority of tasks as they start executing it reduces the set of tasks that can preempt any given task. A subset of FPTS task configurations can be implemented natively on any AUTOSAR/OSEK compatible platform by utilizing the platform's native implementation of non-preemptive task groups via so called internal resources. The limiting factor for this implementation is the number of internal resources that can be associated with any individual task. OSEK and consequently AUTOSAR limit this number to one internal resource per task. In this work, we investigate the impact of this limitation on the schedulability of task sets when cache related preemption delays are taken into account. We also consider the impact of this restriction on the stack size when the tasks are executed on a shared-stack system.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2017
Keywords
Fixed priorities, Fixed priority preemptive, Fixed-priority non-preemptive, Internal resources, Non-preemptive tasks, Pre-emptive scheduling, Preemption thresholds, Schedulability, Scheduling
National Category
Computer Sciences
Identifiers
urn:nbn:se:mdh:diva-35896 (URN)10.23919/DATE.2017.7926990 (DOI)000404171500042 ()2-s2.0-85020171887 (Scopus ID)9783981537093 (ISBN)
Conference
20th Design, Automation and Test in Europe, DATE 2017; SwissTech Convention CenterSwisstech, Lausanne; Switzerland; 27 March - 31 March 2017.
Available from: 2017-06-22 Created: 2017-06-22 Last updated: 2018-01-13Bibliographically approved
Afshar, S., Khalilzad, N., Behnam, M., Bril, R. J. & Nolte, T. (2016). Intra-component Resource Sharing on a Virtual Multiprocessor Platform. In: ACM SIGBED Review: Special Issue on 8th International Workshop on Compositional Theory and Technology for Real-Time Embedded Systems. Paper presented at 8th International Workshop on Compositional Theory and Technology for Real-Time Embedded Systems CRTS'15, 01 Dec 2015, San Antonio, United States (pp. 31-32).
Open this publication in new window or tab >>Intra-component Resource Sharing on a Virtual Multiprocessor Platform
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2016 (English)In: ACM SIGBED Review: Special Issue on 8th International Workshop on Compositional Theory and Technology for Real-Time Embedded Systems, 2016, p. 31-32Conference paper, Published paper (Refereed)
Abstract [en]

Component-based software development facilitates the development process of large and complex software systems. By the advent of multiprocessors, the independently developed components can be integrated on a multi-core platform to achieve an efficient use of system hardware and a decrease in system power consumption and costs. In this paper, we consider a virtual multiprocessor platform where each component can be dynamically allocated to any set of processors of the platform with a maximum concurrency level. Global-EDF is used for intra-component scheduling. The existing analysis for such systems have assumed that tasks are independent. In this paper, we enable intra-component resource sharing for this platform. We investigate using a spin-based resource sharing protocol with the accompanying analysis that extends the existing analysis for independent tasks. We briefly illustrate and evaluate our initial results with an example.

National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-32777 (URN)10.1145/2983185.2983190 (DOI)
External cooperation:
Conference
8th International Workshop on Compositional Theory and Technology for Real-Time Embedded Systems CRTS'15, 01 Dec 2015, San Antonio, United States
Projects
PRESS - Predictable Embedded Software Systems
Available from: 2016-09-01 Created: 2016-08-24 Last updated: 2016-09-01Bibliographically approved
van den Heuvel, M., J. Bril, R., Lukkien, J., Behnam, M. & Nolte, T. (2016). Uniform Interfaces for Resource-Sharing Components in Hierarchically Scheduled Real-Time Systems. In: Real-Time Systems: . InTech
Open this publication in new window or tab >>Uniform Interfaces for Resource-Sharing Components in Hierarchically Scheduled Real-Time Systems
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2016 (English)In: Real-Time Systems, InTech , 2016Chapter in book (Other academic)
Place, publisher, year, edition, pages
InTech, 2016
National Category
Computer Systems
Identifiers
urn:nbn:se:mdh:diva-37327 (URN)10.5772/62691 (DOI)978-953-51-4774-9 (ISBN)
Projects
MRTV - Mälardalen Real-Time VirtualizerPRESS - Predictable Embedded Software Systems
Available from: 2017-11-28 Created: 2017-11-28 Last updated: 2017-11-28Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6234-5117

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