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Documents authored by Nemitz, Catherine E.

Document
DOI: 10.4230/LIPIcs.ECRTS.2026.1
Critical-Section Granularity for Multi-Resource Systems with Nested Critical Sections

Authors: Catherine E. Nemitz, Tanya Amert, and Jonad Pulaj

Published in: LIPIcs, Volume 375, 38th European Conference on Real-Time Systems (ECRTS 2026)

Abstract
Typical models of resource-sharing real-time tasks provide the worst-case task execution time and the duration of each critical section during which a resource is accessed. Such models abstract away the detailed behavior of a task, which may make several individual accesses within a single critical section, incurring access overhead once for the entire critical section. Considering a more fine-grained model with individual access and non-access segments at the forefront gives more control in the system design process; choosing how accesses are grouped into critical sections enables balancing trade-offs between overhead and blocking based on other system parameters, including task deadlines. This paper presents an optimal approach for multi-resource systems that allow any given task to use up to two resources, including support for nested critical sections. This is achieved by extending analysis to multiple resources and constructing a Quadratically-Constrained Integer Program to determine critical sections. This approach is compared to heuristics on the basis of schedulability and its runtime is explored. Further extension to support more resources per task is discussed.
Cite as

Catherine E. Nemitz, Tanya Amert, and Jonad Pulaj. Critical-Section Granularity for Multi-Resource Systems with Nested Critical Sections. In 38th European Conference on Real-Time Systems (ECRTS 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 375, pp. 1:1-1:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{nemitz_et_al:LIPIcs.ECRTS.2026.1,
  author =	{Nemitz, Catherine E. and Amert, Tanya and Pulaj, Jonad},
  title =	{{Critical-Section Granularity for Multi-Resource Systems with Nested Critical Sections}},
  booktitle =	{38th European Conference on Real-Time Systems (ECRTS 2026)},
  pages =	{1:1--1:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-429-1},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{375},
  editor =	{Kritikakou, Angeliki},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2026.1},
  URN =		{urn:nbn:de:0030-drops-265859},
  doi =		{10.4230/LIPIcs.ECRTS.2026.1},
  annote =	{Keywords: Real-time systems, shared resources, fixed-priority scheduling, schedulability}
}
Document
Front Matter
DOI: 10.4230/DARTS.11.1.0
Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee

Authors: Catherine E. Nemitz and Bryan C. Ward

Published in: DARTS, Volume 11, Issue 1, Special Issue of the 37th Euromicro Conference on Real-Time Systems (ECRTS 2025)

Abstract
Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee
Cite as

Special Issue of the 37th Euromicro Conference on Real-Time Systems (ECRTS 2025). Dagstuhl Artifacts Series (DARTS), Volume 11, Issue 1, pp. 0:i-0:x, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@Article{nemitz_et_al:DARTS.11.1.0,
  author =	{Nemitz, Catherine E. and Ward, Bryan C.},
  title =	{{Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee}},
  pages =	{0:i--0:x},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2025},
  volume =	{11},
  number =	{1},
  editor =	{Nemitz, Catherine E. and Ward, Bryan C.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.11.1.0},
  URN =		{urn:nbn:de:0030-drops-237736},
  doi =		{10.4230/DARTS.11.1.0},
  annote =	{Keywords: Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee}
}
Document
Front Matter
DOI: 10.4230/DARTS.10.1.0
Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee

Authors: Matthias Becker and Catherine E. Nemitz

Published in: DARTS, Volume 10, Issue 1, Special Issue of the 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)

Abstract
Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee
Cite as

Special Issue of the 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Dagstuhl Artifacts Series (DARTS), Volume 10, Issue 1, pp. 0:i-0:x, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Article{becker_et_al:DARTS.10.1.0,
  author =	{Becker, Matthias and Nemitz, Catherine E.},
  title =	{{Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee}},
  pages =	{0:i--0:x},
  journal =	{Dagstuhl Artifacts Series},
  ISBN =	{978-3-95977-327-0},
  ISSN =	{2509-8195},
  year =	{2024},
  volume =	{10},
  number =	{1},
  editor =	{Becker, Matthias and Nemitz, Catherine E.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.10.1.0},
  URN =		{urn:nbn:de:0030-drops-203223},
  doi =		{10.4230/DARTS.10.1.0},
  annote =	{Keywords: Front Matter, Table of Contents, Artifact Evaluation Process, Artifact Evaluation Committee}
}
Document
Artifact
DOI: 10.4230/DARTS.7.1.3
Light Reading: Optimizing Reader/Writer Locking for Read-Dominant Real-Time Workloads (Artifact)

Authors: Catherine E. Nemitz, Shai Caspin, James H. Anderson, and Bryan C. Ward

Published in: DARTS, Volume 7, Issue 1, Special Issue of the 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)

Abstract
This paper is directed at reader/writer locking for read-dominant real-time workloads. It is shown that state-of-the-art real-time reader/writer locking protocols are subject to performance limitations when reads dominate, and that existing schedulability analysis fails to leverage the sparsity of writes in this case. A new reader/writer locking-protocol implementation and new inflation-free schedulability analysis are proposed to address these problems. Overhead evaluations of the new implementation show a decrease in overheads of up to 70% over previous implementations, leading to throughput for read operations increasing by up to 450%. Schedulability experiments are presented that show that the analysis results in schedulability improvements of up to 156.8% compared to the existing state-of-the-art approach.
Cite as

Catherine E. Nemitz, Shai Caspin, James H. Anderson, and Bryan C. Ward. Light Reading: Optimizing Reader/Writer Locking for Read-Dominant Real-Time Workloads (Artifact). In Special Issue of the 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021). Dagstuhl Artifacts Series (DARTS), Volume 7, Issue 1, pp. 3:1-3:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@Article{nemitz_et_al:DARTS.7.1.3,
  author =	{Nemitz, Catherine E. and Caspin, Shai and Anderson, James H. and Ward, Bryan C.},
  title =	{{Light Reading: Optimizing Reader/Writer Locking for Read-Dominant Real-Time Workloads (Artifact)}},
  pages =	{3:1--3:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2021},
  volume =	{7},
  number =	{1},
  editor =	{Nemitz, Catherine E. and Caspin, Shai and Anderson, James H. and Ward, Bryan C.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.7.1.3},
  URN =		{urn:nbn:de:0030-drops-139828},
  doi =		{10.4230/DARTS.7.1.3},
  annote =	{Keywords: Reader/writer, real-time, synchronization, spinlock, RMR complexity}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2021.6
Light Reading: Optimizing Reader/Writer Locking for Read-Dominant Real-Time Workloads

Authors: Catherine E. Nemitz, Shai Caspin, James H. Anderson, and Bryan C. Ward

Published in: LIPIcs, Volume 196, 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)

Abstract
This paper is directed at reader/writer locking for read-dominant real-time workloads. It is shown that state-of-the-art real-time reader/writer locking protocols are subject to performance limitations when reads dominate, and that existing schedulability analysis fails to leverage the sparsity of writes in this case. A new reader/writer locking-protocol implementation and new inflation-free schedulability analysis are proposed to address these problems. Overhead evaluations of the new implementation show a decrease in overheads of up to 70% over previous implementations, leading to throughput for read operations increasing by up to 450%. Schedulability experiments are presented that show that the analysis results in schedulability improvements of up to 156.8% compared to the existing state-of-the-art approach.
Cite as

Catherine E. Nemitz, Shai Caspin, James H. Anderson, and Bryan C. Ward. Light Reading: Optimizing Reader/Writer Locking for Read-Dominant Real-Time Workloads. In 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 196, pp. 6:1-6:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{nemitz_et_al:LIPIcs.ECRTS.2021.6,
  author =	{Nemitz, Catherine E. and Caspin, Shai and Anderson, James H. and Ward, Bryan C.},
  title =	{{Light Reading: Optimizing Reader/Writer Locking for Read-Dominant Real-Time Workloads}},
  booktitle =	{33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)},
  pages =	{6:1--6:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-192-4},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{196},
  editor =	{Brandenburg, Bj\"{o}rn B.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2021.6},
  URN =		{urn:nbn:de:0030-drops-139378},
  doi =		{10.4230/LIPIcs.ECRTS.2021.6},
  annote =	{Keywords: Reader/writer, real-time, synchronization, spinlock, RMR complexity}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2018.25
Using Lock Servers to Scale Real-Time Locking Protocols: Chasing Ever-Increasing Core Counts

Authors: Catherine E. Nemitz, Tanya Amert, and James H. Anderson

Published in: LIPIcs, Volume 106, 30th Euromicro Conference on Real-Time Systems (ECRTS 2018)

Abstract
During the past decade, parallelism-related issues have been at the forefront of real-time systems research due to the advent of multicore technologies. In the coming years, such issues will loom ever larger due to increasing core counts. Having more cores means a greater potential exists for platform capacity loss when the available parallelism cannot be fully exploited. In this paper, such capacity loss is considered in the context of real-time locking protocols. In this context, lock nesting becomes a key concern as it can result in transitive blocking chains that force tasks to execute sequentially unnecessarily. Such chains can be quite long on a larger machine. Contention-sensitive real-time locking protocols have been proposed as a means of "breaking" transitive blocking chains, but such protocols tend to have high overhead due to more complicated lock/unlock logic. To ease such overhead, the usage of lock servers is considered herein. In particular, four specific lock-server paradigms are proposed and many nuances concerning their deployment are explored. Experiments are presented that show that, by executing cache hot, lock servers can enable reductions in lock/unlock overhead of up to 86%. Such reductions make contention-sensitive protocols a viable approach in practice.
Cite as

Catherine E. Nemitz, Tanya Amert, and James H. Anderson. Using Lock Servers to Scale Real-Time Locking Protocols: Chasing Ever-Increasing Core Counts. In 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 106, pp. 25:1-25:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{nemitz_et_al:LIPIcs.ECRTS.2018.25,
  author =	{Nemitz, Catherine E. and Amert, Tanya and Anderson, James H.},
  title =	{{Using Lock Servers to Scale Real-Time Locking Protocols: Chasing Ever-Increasing Core Counts}},
  booktitle =	{30th Euromicro Conference on Real-Time Systems (ECRTS 2018)},
  pages =	{25:1--25:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-075-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{106},
  editor =	{Altmeyer, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2018.25},
  URN =		{urn:nbn:de:0030-drops-89789},
  doi =		{10.4230/LIPIcs.ECRTS.2018.25},
  annote =	{Keywords: multiprocess locking protocols, nested locks, priority-inversion blocking, reader/writer locks, real-time locking protocols}
}
Document
DOI: 10.4230/DARTS.4.2.2
Using Lock Servers to Scale Real-Time Locking Protocols: Chasing Ever-Increasing Core Counts (Artifact)

Authors: Catherine E. Nemitz, Tanya Amert, and James H. Anderson

Published in: DARTS, Volume 4, Issue 2, Special Issue of the 30th Euromicro Conference on Real-Time Systems (ECRTS 2018)

Abstract
During the past decade, parallelism-related issues have been at the forefront of real-time systems research due to the advent of multicore technologies. In the coming years, such issues will loom ever larger due to increasing core counts. Having more cores means a greater potential exists for platform capacity loss when the available parallelism cannot be fully exploited. In this work, such capacity loss is considered in the context of real-time locking protocols. In this context, lock nesting becomes a key concern as it can result in transitive blocking chains that force tasks to execute sequentially unnecessarily. Such chains can be quite long on a larger machine. Contention-sensitive real-time locking protocols have been proposed as a means of ``breaking'' transitive blocking chains, but such protocols tend to have high overhead due to more complicated lock/unlock logic. To ease such overhead, the usage of lock servers is considered herein. In particular, four specific lock-server paradigms are proposed and many nuances concerning their deployment are explored. Experiments are presented that show that, by executing cache hot, lock servers can enable reductions in lock/unlock overhead of up to 86\%. Such reductions make contention-sensitive protocols a viable approach in practice. This artifact contains the implementation of two contention-sensitive locking protocol variants implemented with four proposed lock-server paradigms, as well as the experiments with which they were evaluated.
Cite as

Catherine E. Nemitz, Tanya Amert, and James H. Anderson. Using Lock Servers to Scale Real-Time Locking Protocols: Chasing Ever-Increasing Core Counts (Artifact). In Special Issue of the 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Dagstuhl Artifacts Series (DARTS), Volume 4, Issue 2, pp. 2:1-2:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@Article{nemitz_et_al:DARTS.4.2.2,
  author =	{Nemitz, Catherine E. and Amert, Tanya and Anderson, James H.},
  title =	{{Using Lock Servers to Scale Real-Time Locking Protocols: Chasing Ever-Increasing Core Counts (Artifact)}},
  pages =	{2:1--2:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2018},
  volume =	{4},
  number =	{2},
  editor =	{Nemitz, Catherine E. and Amert, Tanya 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.4.2.2},
  URN =		{urn:nbn:de:0030-drops-89704},
  doi =		{10.4230/DARTS.4.2.2},
  annote =	{Keywords: multiprocess locking protocols, nested locks, priority-inversion blocking, reader/writer locks, real-time locking protocols}
}
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