6 Search Results for "Bletsas, Konstantinos"


Document
Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis

Authors: Mario Günzel, Georg von der Brüggen, and Jian-Jia Chen

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)


Abstract
Tasks are called self-suspending if they can yield their ready state (specifically, releasing the processor while having highest priority) despite being incomplete, for instance, to offload computation to an external device or when waiting on access rights for shared resources or data. This self-suspending behavior requires special treatment when applying analytical results to compute worst-case response time bounds. One typical treatment is modeling self-suspension as release jitter in a so-called jitter-based analysis. The state of the art, when considering task-level fixed-priority scheduling, individually quantifies the jitter term of each higher-priority task by its worst-case response time minus its worst-case execution time. This work tightens the jitter term by taking the execution behavior of the other higher-priority tasks into account. Our improved jitter-based analysis analytically dominates the previous jitter-based analysis. Moreover, an evaluation for synthetically generated sporadic tasks demonstrates that this jitter term results in tighter worst-case response time bounds for self-suspending tasks. We observe an improvement for up to 55.89 % of the tasksets compared to the previous jitter-based analysis.

Cite as

Mario Günzel, Georg von der Brüggen, and Jian-Jia Chen. Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 4:1-4:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


Copy BibTex To Clipboard

@InProceedings{gunzel_et_al:LIPIcs.ECRTS.2024.4,
  author =	{G\"{u}nzel, Mario and von der Br\"{u}ggen, Georg and Chen, Jian-Jia},
  title =	{{Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{4:1--4:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.4},
  URN =		{urn:nbn:de:0030-drops-203074},
  doi =		{10.4230/LIPIcs.ECRTS.2024.4},
  annote =	{Keywords: Worst-Case Response Time, WCRT, Jitter, Self-Suspension, Analysis}
}
Document
GCAPS: GPU Context-Aware Preemptive Priority-Based Scheduling for Real-Time Tasks

Authors: Yidi Wang, Cong Liu, Daniel Wong, and Hyoseung Kim

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)


Abstract
Scheduling real-time tasks that utilize GPUs with analyzable guarantees poses a significant challenge due to the intricate interaction between CPU and GPU resources, as well as the complex GPU hardware and software stack. While much research has been conducted in the real-time research community, several limitations persist, including the absence or limited availability of GPU-level preemption, extended blocking times, and/or the need for extensive modifications to program code. In this paper, we propose GCAPS, a GPU Context-Aware Preemptive Scheduling approach for real-time GPU tasks. Our approach exerts control over GPU context scheduling at the device driver level and enables preemption of GPU execution based on task priorities by simply adding one-line macros to GPU segment boundaries. In addition, we provide a comprehensive response time analysis of GPU-using tasks for both our proposed approach as well as the default Nvidia GPU driver scheduling that follows a work-conserving round-robin policy. Through empirical evaluations and case studies, we demonstrate the effectiveness of the proposed approaches in improving taskset schedulability and response time. The results highlight significant improvements over prior work as well as the default scheduling approach, with up to 40% higher schedulability, while also achieving predictable worst-case behavior on Nvidia Jetson embedded platforms.

Cite as

Yidi Wang, Cong Liu, Daniel Wong, and Hyoseung Kim. GCAPS: GPU Context-Aware Preemptive Priority-Based Scheduling for Real-Time Tasks. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 14:1-14:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


Copy BibTex To Clipboard

@InProceedings{wang_et_al:LIPIcs.ECRTS.2024.14,
  author =	{Wang, Yidi and Liu, Cong and Wong, Daniel and Kim, Hyoseung},
  title =	{{GCAPS: GPU Context-Aware Preemptive Priority-Based Scheduling for Real-Time Tasks}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{14:1--14:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.14},
  URN =		{urn:nbn:de:0030-drops-203170},
  doi =		{10.4230/LIPIcs.ECRTS.2024.14},
  annote =	{Keywords: Real-time systems, GPU scheduling}
}
Document
Worst-case Stall Analysis for Multicore Architectures with Two Memory Controllers

Authors: Muhammad Ali Awan, Pedro F. Souto, Konstantinos Bletsas, Benny Akesson, and Eduardo Tovar

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


Abstract
In multicore architectures, there is potential for contention between cores when accessing shared resources, such as system memory. Such contention scenarios are challenging to accurately analyse, from a worst-case timing perspective. One way of making memory contention in multicores more amenable to timing analysis is the use of memory regulation mechanisms. It restricts the number of accesses performed by any given core over time by using periodically replenished per-core budgets. Typically, this assumes that all cores access memory via a single shared memory controller. However, ever-increasing bandwidth requirements have brought about architectures with multiple memory controllers. These control accesses to different memory regions and are potentially shared among all cores. While this presents an opportunity to satisfy bandwidth requirements, existing analysis designed for a single memory controller are no longer safe. This work formulates a worst-case memory stall analysis for a memory-regulated multicore with two memory controllers. This stall analysis can be integrated into the schedulability analysis of systems under fixed-priority partitioned scheduling. Five heuristics for assigning tasks and memory budgets to cores in a stall-cognisant manner are also proposed. We experimentally quantify the cost in terms of extra stall for letting all cores benefit from the memory space offered by both controllers, and also evaluate the five heuristics for different system characteristics.

Cite as

Muhammad Ali Awan, Pedro F. Souto, Konstantinos Bletsas, Benny Akesson, and Eduardo Tovar. Worst-case Stall Analysis for Multicore Architectures with Two Memory Controllers. In 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 106, pp. 2:1-2:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


Copy BibTex To Clipboard

@InProceedings{awan_et_al:LIPIcs.ECRTS.2018.2,
  author =	{Awan, Muhammad Ali and Souto, Pedro F. and Bletsas, Konstantinos and Akesson, Benny and Tovar, Eduardo},
  title =	{{Worst-case Stall Analysis for Multicore Architectures with Two Memory Controllers}},
  booktitle =	{30th Euromicro Conference on Real-Time Systems (ECRTS 2018)},
  pages =	{2:1--2:22},
  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.2018.2},
  URN =		{urn:nbn:de:0030-drops-90025},
  doi =		{10.4230/LIPIcs.ECRTS.2018.2},
  annote =	{Keywords: multiple memory controllers, memory regulation, multicore}
}
Document
Worst-case Stall Analysis for Multicore Architectures with Two Memory Controllers (Artifact)

Authors: Muhammad Ali Awan, Pedro F. Souto, Konstantinos Bletsas, Benny Akesson, and Eduardo Tovar

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


Abstract
This artifact demonstrates the performance of the proposed worst-case memory stall analysis for a memory-regulated multicore with two memory controllers. The memory stall analysis is implemented in Java along with five different stall-cognisant bandwidth-to-core and task-to-core assignment heuristics. It evaluates the performance of these heuristics in terms of schedulability via experiments with synthetic task sets capturing different system characteristics. It also quantifies the cost in terms of extra stall for letting all cores benefit from the memory space offered by both controllers on the given multicore platform.

Cite as

Muhammad Ali Awan, Pedro F. Souto, Konstantinos Bletsas, Benny Akesson, and Eduardo Tovar. Worst-case Stall Analysis for Multicore Architectures with Two Memory Controllers (Artifact). In Special Issue of the 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Dagstuhl Artifacts Series (DARTS), Volume 4, Issue 2, pp. 5:1-5:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


Copy BibTex To Clipboard

@Article{awan_et_al:DARTS.4.2.5,
  author =	{Awan, Muhammad Ali and Souto, Pedro F. and Bletsas, Konstantinos and Akesson, Benny and Tovar, Eduardo},
  title =	{{Worst-case Stall Analysis for Multicore Architectures with Two Memory Controllers (Artifact)}},
  pages =	{5:1--5:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2018},
  volume =	{4},
  number =	{2},
  editor =	{Awan, Muhammad Ali and Souto, Pedro F. and Bletsas, Konstantinos and Akesson, Benny and Tovar, Eduardo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.4.2.5},
  URN =		{urn:nbn:de:0030-drops-89732},
  doi =		{10.4230/DARTS.4.2.5},
  annote =	{Keywords: multiple memory controllers, memory regulation, multicore}
}
Document
Errata for Three Papers (2004-05) on Fixed-Priority Scheduling with Self-Suspensions

Authors: Konstantinos Bletsas, Neil C. Audsley, Wen-Hung Huang, Jian-Jia Chen, and Geoffrey Nelissen

Published in: LITES, Volume 5, Issue 1 (2018). Leibniz Transactions on Embedded Systems, Volume 5, Issue 1


Abstract
The purpose of this article is to (i) highlight the flaws in three previously published works [Audsley, 2004a; Audsley, 2004b; Bletsas, 2005] on the worst-case response time analysis for tasks with self-suspensions and (ii) provide straightforward fixes for those flaws, hence rendering the analysis safe.

Cite as

Konstantinos Bletsas, Neil C. Audsley, Wen-Hung Huang, Jian-Jia Chen, and Geoffrey Nelissen. Errata for Three Papers (2004-05) on Fixed-Priority Scheduling with Self-Suspensions. In LITES, Volume 5, Issue 1 (2018). Leibniz Transactions on Embedded Systems, Volume 5, Issue 1, pp. 02:1-02:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


Copy BibTex To Clipboard

@Article{bletsas_et_al:LITES-v005-i001-a002,
  author =	{Bletsas, Konstantinos and Audsley, Neil C. and Huang, Wen-Hung and Chen, Jian-Jia and Nelissen, Geoffrey},
  title =	{{Errata for Three Papers (2004-05) on Fixed-Priority Scheduling with Self-Suspensions}},
  journal =	{Leibniz Transactions on Embedded Systems},
  pages =	{02:1--02:20},
  ISSN =	{2199-2002},
  year =	{2018},
  volume =	{5},
  number =	{1},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v005-i001-a002},
  doi =		{10.4230/LITES-v005-i001-a002},
  annote =	{Keywords: real-time, scheduling, self-suspension, worst-case response time analysis}
}
Document
Mixed-Criticality Scheduling with Dynamic Redistribution of Shared Cache

Authors: Muhammad Ali Awan, Konstantinos Bletsas, Pedro F. Souto, Benny Akesson, and Eduardo Tovar

Published in: LIPIcs, Volume 76, 29th Euromicro Conference on Real-Time Systems (ECRTS 2017)


Abstract
The design of mixed-criticality systems often involves painful tradeoffs between safety guarantees and performance. However, the use of more detailed architectural models in the design and analysis of scheduling arrangements for mixed-criticality systems can provide greater confidence in the analysis, but also opportunities for better performance. Motivated by this view, we propose an extension of Vestal's model for mixed-criticality multicore systems that (i) accounts for the per-task partitioning of the last-level cache and (ii) supports the dynamic reassignment, for better schedulability, of cache portions initially reserved for lower-criticality tasks to the higher-criticality tasks, when the system switches to high-criticality mode. To this model, we apply partitioned EDF scheduling with Ekberg and Yi's deadline-scaling technique. Our schedulability analysis and scalefactor calculation is cognisant of the cache resources assigned to each task, by using WCET estimates that take into account these resources. It is hence able to leverage the dynamic reconfiguration of the cache partitioning, at mode change, for better performance, in terms of provable schedulability. We also propose heuristics for partitioning the cache in low- and high-criticality mode, that promote schedulability. Our experiments with synthetic task sets, indicate tangible improvements in schedulability compared to a baseline cache-aware arrangement where there is no redistribution of cache resources from low- to high-criticality tasks in the event of a mode change.

Cite as

Muhammad Ali Awan, Konstantinos Bletsas, Pedro F. Souto, Benny Akesson, and Eduardo Tovar. Mixed-Criticality Scheduling with Dynamic Redistribution of Shared Cache. In 29th Euromicro Conference on Real-Time Systems (ECRTS 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 76, pp. 18:1-18:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


Copy BibTex To Clipboard

@InProceedings{awan_et_al:LIPIcs.ECRTS.2017.18,
  author =	{Awan, Muhammad Ali and Bletsas, Konstantinos and Souto, Pedro F. and Akesson, Benny and Tovar, Eduardo},
  title =	{{Mixed-Criticality Scheduling with Dynamic Redistribution of Shared Cache}},
  booktitle =	{29th Euromicro Conference on Real-Time Systems (ECRTS 2017)},
  pages =	{18:1--18:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-037-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{76},
  editor =	{Bertogna, Marko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2017.18},
  URN =		{urn:nbn:de:0030-drops-71710},
  doi =		{10.4230/LIPIcs.ECRTS.2017.18},
  annote =	{Keywords: Mixed Criticality Scheduling, Vestal Model, Dynamic Redistribution of Shared Cache, Shared Last-level Cache Analysis, Cache-aware Scheduling}
}
  • Refine by Author
  • 4 Bletsas, Konstantinos
  • 3 Akesson, Benny
  • 3 Awan, Muhammad Ali
  • 3 Souto, Pedro F.
  • 3 Tovar, Eduardo
  • Show More...

  • Refine by Classification
  • 4 Computer systems organization → Real-time systems
  • 2 Computer systems organization → Embedded systems
  • 2 Software and its engineering → Real-time schedulability
  • 1 Computer systems organization → Embedded and cyber-physical systems
  • 1 Computer systems organization → Real-time operating systems
  • Show More...

  • Refine by Keyword
  • 2 memory regulation
  • 2 multicore
  • 2 multiple memory controllers
  • 1 Analysis
  • 1 Cache-aware Scheduling
  • Show More...

  • Refine by Type
  • 6 document

  • Refine by Publication Year
  • 3 2018
  • 2 2024
  • 1 2017