2 Search Results for "Mills, Alex"

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)

Copy BibTex To Clipboard

@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-dev.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
DOI: 10.4230/DagSemProc.10071.4
A Stochastic Framework for Multiprocessor Soft Real-Time Scheduling

Authors: James Anderson and Alex Mills

Published in: Dagstuhl Seminar Proceedings, Volume 10071, Scheduling (2010)

Abstract
Prior work has shown that the global earliest-deadline-first (GEDF) scheduling algorithm ensures bounded deadline tardiness on multiprocessors with no utilization loss; therefore, GEDF may be a good candidate scheduling algorithm for soft real-time workloads. However, such workloads are often implemented assuming an average-case provisioning, and in prior tardiness-bound derivations for GEDF, worst-case execution costs are assumed. As worst-case costs can be orders of magnitude higher than average-case costs, using a worst-case provisioning may result in significant wasted processing capacity. In this paper, prior tardiness-bound derivations for GEDF are generalized so that execution times are probabilistic, and a bound on expected (mean) tardiness is derived. It is shown that, as long as the total expected utilization is strictly less than the number of available processors, the expected tardiness of every task is bounded under GEDF. The result also implies that any quantile of the tardiness distribution is also bounded. The uploaded paper is from the upcoming RTAS. I would like to hear suggestions about how to ease the assumption of independent execution times in this analysis.
Cite as

James Anderson and Alex Mills. A Stochastic Framework for Multiprocessor Soft Real-Time Scheduling. In Scheduling. Dagstuhl Seminar Proceedings, Volume 10071, pp. 1-10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{anderson_et_al:DagSemProc.10071.4,
  author =	{Anderson, James and Mills, Alex},
  title =	{{A Stochastic Framework for Multiprocessor Soft Real-Time Scheduling}},
  booktitle =	{Scheduling},
  pages =	{1--10},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{10071},
  editor =	{Susanne Albers and Sanjoy K. Baruah and Rolf H. M\"{o}hring and Kirk Pruhs},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.10071.4},
  URN =		{urn:nbn:de:0030-drops-25374},
  doi =		{10.4230/DagSemProc.10071.4},
  annote =	{Keywords: GEDF, multiprocessor, tardiness}
}
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