3 Search Results for "Goossens, Joël"

Document
DOI: 10.4230/LIPIcs.ECRTS.2019.7
Implementation of Memory Centric Scheduling for COTS Multi-Core Real-Time Systems

Authors: Juan M. Rivas, Joël Goossens, Xavier Poczekajlo, and Antonio Paolillo

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

Abstract
The demands for high performance computing with a low cost and low power consumption are driving a transition towards multi-core processors in many consumer and industrial applications. However, the adoption of multi-core processors in the domain of real-time systems faces a series of challenges that has been the focus of great research intensity during the last decade. These challenges arise in great part from the non real-time nature of the hardware arbiters that schedule the access to shared resources, such as the main memory. One solution proposed in the literature is called Memory Centric Scheduling, which defines a separate software scheduler for the sections of the tasks that will access the main memory, hence circumventing the low level unpredictable hardware arbiters. Several Memory Centric schedulers and associated theoretical analyses have been proposed, but as far as we know, no actual implementation of the required OS-level underpinnings to support dynamic event-driven Memory Centric Scheduling has been presented before. In this paper we aim to fill this gap, targeting cache based COTS multi-core systems. We will confirm via measurements the main theoretical benefits of Memory Centric Scheduling (e.g. task isolation). Furthermore, we will describe an effective schedulability analysis using concepts from distributed systems.
Cite as

Juan M. Rivas, Joël Goossens, Xavier Poczekajlo, and Antonio Paolillo. Implementation of Memory Centric Scheduling for COTS Multi-Core Real-Time Systems. In 31st Euromicro Conference on Real-Time Systems (ECRTS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 133, pp. 7:1-7:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{rivas_et_al:LIPIcs.ECRTS.2019.7,
  author =	{Rivas, Juan M. and Goossens, Jo\"{e}l and Poczekajlo, Xavier and Paolillo, Antonio},
  title =	{{Implementation of Memory Centric Scheduling for COTS Multi-Core Real-Time Systems}},
  booktitle =	{31st Euromicro Conference on Real-Time Systems (ECRTS 2019)},
  pages =	{7:1--7:23},
  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-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2019.7},
  URN =		{urn:nbn:de:0030-drops-107448},
  doi =		{10.4230/LIPIcs.ECRTS.2019.7},
  annote =	{Keywords: real-time, multi-core, memory centric, predictability, implementation, rtos}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2019.14
Dual Priority Scheduling is Not Optimal

Authors: Pontus Ekberg

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

Abstract
In dual priority scheduling, periodic tasks are executed in a fixed-priority manner, but each job has two phases with different priorities. The second phase is entered after a fixed amount of time has passed since the release of the job, at which point the job changes its priority. Dual priority scheduling was introduced by Burns and Wellings in 1993 and was shown to successfully schedule many task sets that are not schedulable with ordinary (single) fixed-priority scheduling. Burns and Wellings conjectured that dual priority scheduling is an optimal scheduling algorithm for synchronous periodic tasks with implicit deadlines on preemptive uniprocessors. We demonstrate the falsity of this conjecture, as well as of some related conjectures that have since been stated. This is achieved by means of computer-verified counterexamples.
Cite as

Pontus Ekberg. Dual Priority Scheduling is Not Optimal. In 31st Euromicro Conference on Real-Time Systems (ECRTS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 133, pp. 14:1-14:9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{ekberg:LIPIcs.ECRTS.2019.14,
  author =	{Ekberg, Pontus},
  title =	{{Dual Priority Scheduling is Not Optimal}},
  booktitle =	{31st Euromicro Conference on Real-Time Systems (ECRTS 2019)},
  pages =	{14:1--14:9},
  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-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2019.14},
  URN =		{urn:nbn:de:0030-drops-107519},
  doi =		{10.4230/LIPIcs.ECRTS.2019.14},
  annote =	{Keywords: Scheduling, real time systems, dual priority}
}
Document
DOI: 10.4230/LITES-v003-i001-a004
Optimal Scheduling of Periodic Gang Tasks

Authors: Joël Goossens and Pascal Richard

Published in: LITES, Volume 3, Issue 1 (2016). Leibniz Transactions on Embedded Systems, Volume 3, Issue 1

Abstract
The gang scheduling of parallel implicit-deadline periodic task systems upon identical multiprocessor platforms is considered. In this scheduling problem, parallel tasks use several processors simultaneously. We propose two DPFAIR (deadline partitioning) algorithms that schedule all jobs in every interval of time delimited by two subsequent deadlines. These algorithms define a static schedule pattern that is stretched at run-time in every interval of the DPFAIR schedule. The first algorithm is based on linear programming and is the first one to be proved  optimal for the considered gang scheduling problem. Furthermore, it runs in polynomial time for a fixed number m of processors and an efficient implementation is fully detailed. The second algorithm is an approximation algorithm based on a fixed-priority rule that is competitive under resource augmentation analysis in order to compute an optimal schedule pattern. Precisely, its speedup factor is bounded by (2-1/m). Both algorithms are also evaluated through intensive numerical experiments.
Cite as

Joël Goossens and Pascal Richard. Optimal Scheduling of Periodic Gang Tasks. In LITES, Volume 3, Issue 1 (2016). Leibniz Transactions on Embedded Systems, Volume 3, Issue 1, pp. 04:1-04:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@Article{goossens_et_al:LITES-v003-i001-a004,
  author =	{Goossens, Jo\"{e}l and Richard, Pascal},
  title =	{{Optimal Scheduling of Periodic Gang Tasks}},
  journal =	{Leibniz Transactions on Embedded Systems},
  pages =	{04:1--04:18},
  ISSN =	{2199-2002},
  year =	{2016},
  volume =	{3},
  number =	{1},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LITES-v003-i001-a004},
  doi =		{10.4230/LITES-v003-i001-a004},
  annote =	{Keywords: Real-time systems, Scheduling, Parallel tasks}
}
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