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Documents authored by Osborne, Sims Hill

Document
Artifact
DOI: 10.4230/DARTS.6.1.1
Simultaneous Multithreading and Hard Real Time: Can it be Safe? (Artifact)

Authors: Sims Hill Osborne, Joshua J. Bakita, and James H. Anderson

Published in: DARTS, Volume 6, Issue 1, Special Issue of the 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)

Abstract
The applicability of Simultaneous Multithreading (SMT) to real-time systems has been hampered by the difficulty of obtaining reliable execution costs in an SMT-enabled system. This problem is addressed from two directions. A scheduler is introduced, CERT-MT, that minimizes SMT-related timing variations, and two new timing analysis methods - one based on the binomial distribution and one based on Cantelli’s Inequality - are given. Both methods estimate probabilistic WCETs and attach statistical confidence levels to those estimates. The timing analyses are applied to tasks executing with and without SMT, and it is found that in some cases, two tasks utilizing SMT can be safely executed in less time than would be needed for either task by itself. A large-scale schedulability study is conducted, showing that CERT-MT can schedule systems with total utilizations twice what could otherwise be achieved. This artifact includes benchmark experiments used to compare execution times with and without SMT and code to analyze the benchmark experiments and duplicate the reported schedulability experiments.
Cite as

Sims Hill Osborne, Joshua J. Bakita, and James H. Anderson. Simultaneous Multithreading and Hard Real Time: Can it be Safe? (Artifact). In Special Issue of the 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020). Dagstuhl Artifacts Series (DARTS), Volume 6, Issue 1, pp. 1:1-1:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@Article{osborne_et_al:DARTS.6.1.1,
  author =	{Osborne, Sims Hill and Bakita, Joshua J. and Anderson, James H.},
  title =	{{Simultaneous Multithreading and Hard Real Time: Can it be Safe? (Artifact)}},
  pages =	{1:1--1:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2020},
  volume =	{6},
  number =	{1},
  editor =	{Osborne, Sims Hill and Bakita, Joshua J. and Anderson, James H.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.6.1.1},
  URN =		{urn:nbn:de:0030-drops-123915},
  doi =		{10.4230/DARTS.6.1.1},
  annote =	{Keywords: real-time systems, simultaneous multithreading, real-time, scheduling algorithms, timing analysis, probability, statistics}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2020.14
Simultaneous Multithreading and Hard Real Time: Can It Be Safe?

Authors: Sims Hill Osborne and James H. Anderson

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

Abstract
The applicability of Simultaneous Multithreading (SMT) to real-time systems has been hampered by the difficulty of obtaining reliable execution costs in an SMT-enabled system. This problem is addressed by introducing a scheduling framework, called CERT-MT, that combines scheduling-aware timing analysis with a cyclic-executive scheduler in a way that minimizes SMT-related timing variations. The proposed scheduling-aware timing analysis is based on maximum observed execution times and accounts for the uncertainty inherent in measurement-based timing analysis. The timing analysis is found to work for tasks with and without SMT, though some adjustments are required in the former case. A large-scale schedulability study is presented that shows CERT-MT can schedule systems with total utilizations approaching 1.4 times the core count, without sacrificing safety.
Cite as

Sims Hill Osborne and James H. Anderson. Simultaneous Multithreading and Hard Real Time: Can It Be Safe?. In 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 165, pp. 14:1-14:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{osborne_et_al:LIPIcs.ECRTS.2020.14,
  author =	{Osborne, Sims Hill and Anderson, James H.},
  title =	{{Simultaneous Multithreading and Hard Real Time: Can It Be Safe?}},
  booktitle =	{32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)},
  pages =	{14:1--14:25},
  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.2020.14},
  URN =		{urn:nbn:de:0030-drops-123778},
  doi =		{10.4230/LIPIcs.ECRTS.2020.14},
  annote =	{Keywords: real-time systems, simultaneous multithreading, hard real-time, scheduling algorithms, probability, statistics, timing analysis}
}
Document
Artifact
DOI: 10.4230/DARTS.5.1.8
Simultaneous Multithreading Applied to Real Time (Artifact)

Authors: Sims Hill Osborne, Joshua J. Bakita, and James H. Anderson

Published in: DARTS, Volume 5, Issue 1, Special Issue of the 31st Euromicro Conference on Real-Time Systems (ECRTS 2019)

Abstract
Existing models used in real-time scheduling are inadequate to take advantage of simultaneous multithreading (SMT), which has been shown to improve performance in many areas of computing, but has seen little application to real-time systems. The SMART task model, which allows for combining SMT and real time by accounting for the variable task execution costs caused by SMT, is introduced, along with methods and conditions for scheduling SMT tasks under global earliest-deadline-first scheduling. The benefits of using SMT are demonstrated through a large-scale schedulability study in which we show that task systems with utilizations 30% larger than what would be schedulable without SMT can be correctly scheduled. This artifact includes benchmark experiments used to compare execution times with and without SMT and code to duplicate the reported schedulability experiments.
Cite as

Sims Hill Osborne, Joshua J. Bakita, and James H. Anderson. Simultaneous Multithreading Applied to Real Time (Artifact). In Special Issue of the 31st Euromicro Conference on Real-Time Systems (ECRTS 2019). Dagstuhl Artifacts Series (DARTS), Volume 5, Issue 1, pp. 8:1-8:2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@Article{osborne_et_al:DARTS.5.1.8,
  author =	{Osborne, Sims Hill and Bakita, Joshua J. and Anderson, James H.},
  title =	{{Simultaneous Multithreading Applied to Real Time}},
  pages =	{8:1--8:2},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2019},
  volume =	{5},
  number =	{1},
  editor =	{Osborne, Sims Hill and Bakita, Joshua J. and Anderson, James H.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.5.1.8},
  URN =		{urn:nbn:de:0030-drops-107362},
  doi =		{10.4230/DARTS.5.1.8},
  annote =	{Keywords: real-time systems, simultaneous multithreading, soft real-time, scheduling algorithms}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2019.3
Simultaneous Multithreading Applied to Real Time

Authors: Sims Hill Osborne, Joshua J. Bakita, and James H. Anderson

Published in: LIPIcs, Volume 133, 31st Euromicro Conference on Real-Time Systems (ECRTS 2019)

Abstract
Existing models used in real-time scheduling are inadequate to take advantage of simultaneous multithreading (SMT), which has been shown to improve performance in many areas of computing, but has seen little application to real-time systems. The SMART task model, which allows for combining SMT and real time by accounting for the variable task execution costs caused by SMT, is introduced, along with methods and conditions for scheduling SMT tasks under global earliest-deadline-first scheduling. The benefits of using SMT are demonstrated through a large-scale schedulability study in which we show that task systems with utilizations 30% larger than what would be schedulable without SMT can be correctly scheduled.
Cite as

Sims Hill Osborne, Joshua J. Bakita, and James H. Anderson. Simultaneous Multithreading Applied to Real Time. In 31st Euromicro Conference on Real-Time Systems (ECRTS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 133, pp. 3:1-3:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{osborne_et_al:LIPIcs.ECRTS.2019.3,
  author =	{Osborne, Sims Hill and Bakita, Joshua J. and Anderson, James H.},
  title =	{{Simultaneous Multithreading Applied to Real Time}},
  booktitle =	{31st Euromicro Conference on Real-Time Systems (ECRTS 2019)},
  pages =	{3:1--3:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-110-8},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{133},
  editor =	{Quinton, Sophie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2019.3},
  URN =		{urn:nbn:de:0030-drops-107400},
  doi =		{10.4230/LIPIcs.ECRTS.2019.3},
  annote =	{Keywords: real-time systems, simultaneous multithreading, soft real-time, scheduling algorithms}
}
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