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Documents authored by Dobrin, Radu


Document
Improving the Accuracy of Cache-Aware Response Time Analysis Using Preemption Partitioning

Authors: Filip Marković, Jan Carlson, Sebastian Altmeyer, and Radu Dobrin

Published in: LIPIcs, Volume 165, 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)


Abstract
Schedulability analyses for preemptive real-time systems need to take into account cache-related preemption delays (CRPD) caused by preemptions between the tasks. The estimation of the CRPD values must be sound, i.e. it must not be lower than the worst-case CRPD that may occur at runtime, but also should minimise the pessimism of estimation. The existing methods over-approximate the computed CRPD upper bounds by accounting for multiple preemption combinations which cannot occur simultaneously during runtime. This over-approximation may further lead to the over-approximation of the worst-case response times of the tasks, and therefore a false-negative estimation of the system’s schedulability. In this paper, we propose a more precise cache-aware response time analysis for sporadic real-time systems under fully-preemptive fixed priority scheduling. The evaluation shows a significant improvement over the existing state of the art approaches.

Cite as

Filip Marković, Jan Carlson, Sebastian Altmeyer, and Radu Dobrin. Improving the Accuracy of Cache-Aware Response Time Analysis Using Preemption Partitioning. In 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 165, pp. 5:1-5:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{markovic_et_al:LIPIcs.ECRTS.2020.5,
  author =	{Markovi\'{c}, Filip and Carlson, Jan and Altmeyer, Sebastian and Dobrin, Radu},
  title =	{{Improving the Accuracy of Cache-Aware Response Time Analysis Using Preemption Partitioning}},
  booktitle =	{32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)},
  pages =	{5:1--5:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-152-8},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{165},
  editor =	{V\"{o}lp, Marcus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2020.5},
  URN =		{urn:nbn:de:0030-drops-123682},
  doi =		{10.4230/LIPIcs.ECRTS.2020.5},
  annote =	{Keywords: Real-time systems, Fixed-Priority Preemptive Scheduling, Preemption delay}
}
Document
On Fault-Tolerant Scheduling of Time Sensitive Networks

Authors: Radu Dobrin, Nitin Desai, and Sasikumar Punnekkat

Published in: OASIcs, Volume 73, 4th International Workshop on Security and Dependability of Critical Embedded Real-Time Systems (CERTS 2019)


Abstract
Time sensitive networking (TSN) is gaining attention in industrial automation networks since it brings essential real-time capabilities at the data link layer. Though it can provide deterministic latency under error free conditions, TSN still largely depends on space redundancy for improved reliability. In many scenarios, time redundancy could be an adequate as well as cost efficient alternative. Time redundancy in turn will have implications due to the need for over-provisions needed for timeliness guarantees. In this paper, we discuss how to embed fault-tolerance capability into TSN schedules and describe our approach using a simple example.

Cite as

Radu Dobrin, Nitin Desai, and Sasikumar Punnekkat. On Fault-Tolerant Scheduling of Time Sensitive Networks. In 4th International Workshop on Security and Dependability of Critical Embedded Real-Time Systems (CERTS 2019). Open Access Series in Informatics (OASIcs), Volume 73, pp. 5:1-5:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)


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@InProceedings{dobrin_et_al:OASIcs.CERTS.2019.5,
  author =	{Dobrin, Radu and Desai, Nitin and Punnekkat, Sasikumar},
  title =	{{On Fault-Tolerant Scheduling of Time Sensitive Networks}},
  booktitle =	{4th International Workshop on Security and Dependability of Critical Embedded Real-Time Systems (CERTS 2019)},
  pages =	{5:1--5:12},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-119-1},
  ISSN =	{2190-6807},
  year =	{2019},
  volume =	{73},
  editor =	{Asplund, Mikael and Paulitsch, Michael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.CERTS.2019.5},
  URN =		{urn:nbn:de:0030-drops-108965},
  doi =		{10.4230/OASIcs.CERTS.2019.5},
  annote =	{Keywords: Time sensitive networks(TSN), Fault-tolerant schedule, Time redundancy}
}
Document
Tightening the Bounds on Cache-Related Preemption Delay in Fixed Preemption Point Scheduling

Authors: Filip Markovic, Jan Carlson, and Radu Dobrin

Published in: OASIcs, Volume 57, 17th International Workshop on Worst-Case Execution Time Analysis (WCET 2017)


Abstract
Limited Preemptive Fixed Preemption Point scheduling (LP-FPP) has the ability to decrease and control the preemption-related overheads in the real-time task systems, compared to other limited or fully preemptive scheduling approaches. However, existing methods for computing the preemption overheads in LP-FPP systems rely on over-approximation of the evicting cache blocks (ECB) calculations, potentially leading to pessimistic schedulability analysis. In this paper, we propose a novel method for preemption cost calculation that exploits the benefits of the LP-FPP task model both at the scheduling and cache analysis level. The method identifies certain infeasible preemption combinations, based on analysis on the scheduling level, and combines it with cache analysis information into a constraint problem from which less pessimistic upper bounds on cache-related preemption delays (CRPD) can be derived. The evaluation results indicate that our proposed method has the potential to significantly reduce the upper bound on CRPD, by up to 50% in our experiments, compared to the existing over-approximating calculations of the eviction scenarios.

Cite as

Filip Markovic, Jan Carlson, and Radu Dobrin. Tightening the Bounds on Cache-Related Preemption Delay in Fixed Preemption Point Scheduling. In 17th International Workshop on Worst-Case Execution Time Analysis (WCET 2017). Open Access Series in Informatics (OASIcs), Volume 57, pp. 4:1-4:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@InProceedings{markovic_et_al:OASIcs.WCET.2017.4,
  author =	{Markovic, Filip and Carlson, Jan and Dobrin, Radu},
  title =	{{Tightening the Bounds on Cache-Related Preemption Delay in Fixed Preemption Point Scheduling}},
  booktitle =	{17th International Workshop on Worst-Case Execution Time Analysis (WCET 2017)},
  pages =	{4:1--4:11},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-057-6},
  ISSN =	{2190-6807},
  year =	{2017},
  volume =	{57},
  editor =	{Reineke, Jan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2017.4},
  URN =		{urn:nbn:de:0030-drops-73066},
  doi =		{10.4230/OASIcs.WCET.2017.4},
  annote =	{Keywords: Real-time systems, CRPD Analysis, WCET analysis, Limited Preemptive Scheduling, Fixed Preemption Point Approach}
}
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