3 Search Results for "Melhem, Rami"


Document
Utility-Based Scheduling of (m,k)-firm Real-Time Tasks - New Empirical Results

Authors: Florian Kluge

Published in: LITES, Volume 4, Issue 1 (2017). Leibniz Transactions on Embedded Systems, Volume 4, Issue 1


Abstract
The concept of a firm real-time task implies the notion of a firm deadline that should not be missed by the jobs of this task. If a deadline miss occurs, the concerned job yields no value to the system. For some applications domains, this restrictive notion can be relaxed. For example, robust control systems can tolerate that single executions of a control loop miss their deadlines, and still yield an acceptable behaviour. Thus, systems can be developed under more optimistic assumptions, e.g. by allowing overloads. However, care must be taken that deadline misses do not accumulate. This restriction can be expressed by the model of (m,k)-firm real-time tasks that require that from any k consecutive jobs at least m are executed successfully. In this article, we extend our prior work on the MKU scheduling heuristic. MKU uses history-cognisant utility functions as means for making decisions in overload situations. We present new theoretical results on MKU and on other schedulers for (m,k)-firm real-time tasks. Based on extensive simulations, we assess the performance of these schedulers. The results allow us to identify task set characteristics that can be used as guidelines for choosing a scheduler for a concrete use case.

Cite as

Florian Kluge. Utility-Based Scheduling of (m,k)-firm Real-Time Tasks - New Empirical Results. In LITES, Volume 4, Issue 1 (2017). Leibniz Transactions on Embedded Systems, Volume 4, Issue 1, pp. 02:1-02:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@Article{kluge:LITES-v004-i001-a002,
  author =	{Kluge, Florian},
  title =	{{Utility-Based Scheduling of (m,k)-firm Real-Time Tasks - New Empirical Results}},
  journal =	{Leibniz Transactions on Embedded Systems},
  pages =	{02:1--02:25},
  ISSN =	{2199-2002},
  year =	{2017},
  volume =	{4},
  number =	{1},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v004-i001-a002},
  URN =		{urn:nbn:de:0030-drops-192635},
  doi =		{10.4230/LITES-v004-i001-a002},
  annote =	{Keywords: Real-time Scheduling, (m, k)-Firm Real-Time Tasks}
}
Document
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.dagstuhl.de/entities/document/10.4230/LITES-v003-i001-a004},
  URN =		{urn:nbn:de:0030-drops-192593},
  doi =		{10.4230/LITES-v003-i001-a004},
  annote =	{Keywords: Real-time systems, Scheduling, Parallel tasks}
}
Document
Energy Conservation in Memory Hierarchies using Power-Aware Cached-DRAM

Authors: Daniel Mossé, Nevine AbouGhazaleh, Bruce Childers, and Rami Melhem

Published in: Dagstuhl Seminar Proceedings, Volume 5141, Power-aware Computing Systems (2005)


Abstract
Main memory has become one of the largest contributors to overall energy consumption and offers many opportunities for power/energy reduction. In this paper, we propose a new memory organization, called {em Power-Aware Cached-DRAM} (PA-CDRAM), that integrates a moderately sized cache directly into a memory device. We use this cache to turn a memory bank off immediately after a memory access to reduce energy consumption. While other work has used CDRAM to improve memory performance, we modify CDRAM to reduce energy consumption. In this paper, we describe our memory organization and describe the challenges for achieving low energy consumption and how to address them. We evaluate the approach using a cycle accurate processor and memory simulator. Our results show that PA-CDRAM achieves an average 28% improvement in the energy-delay product when compared to a time-out power management technique.

Cite as

Daniel Mossé, Nevine AbouGhazaleh, Bruce Childers, and Rami Melhem. Energy Conservation in Memory Hierarchies using Power-Aware Cached-DRAM. In Power-aware Computing Systems. Dagstuhl Seminar Proceedings, Volume 5141, pp. 1-10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2005)


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@InProceedings{mosse_et_al:DagSemProc.05141.5,
  author =	{Moss\'{e}, Daniel and AbouGhazaleh, Nevine and Childers, Bruce and Melhem, Rami},
  title =	{{Energy Conservation in Memory Hierarchies using Power-Aware Cached-DRAM}},
  booktitle =	{Power-aware Computing Systems},
  pages =	{1--10},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2005},
  volume =	{5141},
  editor =	{Luca Benini and Ulrich Kremer and Christian W. Probst and Peter Schelkens},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.05141.5},
  URN =		{urn:nbn:de:0030-drops-3049},
  doi =		{10.4230/DagSemProc.05141.5},
  annote =	{Keywords: Memory power management, cached DRAM}
}
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