Cluster scheduling, where processors are grouped into clusters and the tasks that are allocated to one cluster are scheduled by a global scheduler, has attracted attention in multiprocessor real-timesystems research ...
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ISBN:
(纸本)9780769541556
Cluster scheduling, where processors are grouped into clusters and the tasks that are allocated to one cluster are scheduled by a global scheduler, has attracted attention in multiprocessor real-timesystems research recently. In this paper, by adopting optimal global schedulers within each cluster, first we investigate the worstcase utilization bound for cluster scheduling. Specifically, for a system with m homogeneous clusters where each cluster has k processors, we show that the worstcase achievable system utilization is left perpendicular k/alpha right perpendicular . m+1/left perpendicular k/alpha right perpendicular + 1 . k, where a is the maximum utilization for the periodic tasks considered. By focusing on an efficient optimal global scheduler, namely the boundary-fair (Bfair) algorithm, we propose a period-aware partitioning heuristic aiming at reducing the scheduling overhead. Simulation results show that the percentage of task sets that can be scheduled is significantly improved under cluster scheduling even for small-size clusters (e.g., k = 2). Moreover, the proposed period-aware partitioning heuristic markedly reduces the scheduling overhead of cluster scheduling with Bfair.
Withthe widespread use of multi-core processors, specialized applications requiring parallel processing can be run on general desktops. In this study, we measure and analyze the parallel performance of LAMMPS, a clas...
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ISBN:
(纸本)9780769550886
Withthe widespread use of multi-core processors, specialized applications requiring parallel processing can be run on general desktops. In this study, we measure and analyze the parallel performance of LAMMPS, a classical well-known molecular dynamics code, on single multi-core systems. In order to check the parallel efficiency on single machines, the various types of simulations with LAMMPS were performed with MPI and OpenMP. Although LAMMPS was run on a single machine, MPI based LAMMPS showed higher performance, because LAMMPS has been designed based on MPI and only some part of LAMMPS was parallelized with OpenMP. the preliminary experiments also showed that the memory sub-system affects the performance of LAMMPS.
When real-timeembedded system software needs to be upgraded, it will be more dependable if the new software is sufficiently tested on the actual deployment platform. the challenge is to provide a safeguard for protec...
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ISBN:
(纸本)0769523463
When real-timeembedded system software needs to be upgraded, it will be more dependable if the new software is sufficiently tested on the actual deployment platform. the challenge is to provide a safeguard for protecting the normal operations from faulty upgrades. However, the safeguard must be not only efficient but also able to be added and taken away as needed without shutting down the normal operations. We have developed an architecture based an Simplex Architecture and Process Resurrection and have applied it to the inverted pendulum control system. the measurements show that the overhead is small and justifiable.
Until recently, embeddedcomputing was a niche discipline, but it is now part of standard industrial practice. the increasing sophistication of embeddedapplications is matched by new demands on system performance, es...
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ISBN:
(纸本)0769520723
Until recently, embeddedcomputing was a niche discipline, but it is now part of standard industrial practice. the increasing sophistication of embeddedapplications is matched by new demands on system performance, especially real-time, and on both interoperability and development process. In this note, I will describe some of the challenges and some new applications for real-time outside traditional areas.
Each domain has its own interpretation of time. We propose to extend UML, which is more and more used in the domain of real-timeembeddedapplications, with. a concept of time inherited from reactive system modeling :...
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ISBN:
(纸本)9780769529752
Each domain has its own interpretation of time. We propose to extend UML, which is more and more used in the domain of real-timeembeddedapplications, with. a concept of time inherited from reactive system modeling : multiform time. After a brief review of some UML profiles, we present our extensions and we illustrate-on an example from the automotive industry-how to represent and to constraint behaviors depending on multiform time. We advocate that this model of time offers wider possibilities than restricting models only to the physical time.
Driving assistance systems are progressively introduced to enhance safety and comfort in passenger vehicles. they increasingly rely on information stored in digital navigation maps. However maps can be obsolete or con...
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ISBN:
(纸本)9781467330633
Driving assistance systems are progressively introduced to enhance safety and comfort in passenger vehicles. they increasingly rely on information stored in digital navigation maps. However maps can be obsolete or contain errors, resulting in malfunctions of context based driving assistance systems and possibly generating hazardous situations. this paper aims at making the vehicle able to detect and localise map errors in an autonomous manner using its embedded sensors. the proposed approach relies on the sequential generation and monitoring of residuals. the vehicle estimated trajectory is compared statistically withthe geometric data in the map. the approach allows driving assistance functions to know if they can rely on the map in real-time and to store this information for future journeys. the method is very efficient in terms of computational load which makes embeddedapplications possible. Performance is assessed using vehicle data acquired in real traffic conditions, which is then compared with an outdated navigation map.
the message scheduling is an essential mechanism in the context of Nerworked Control systems (NCS) which are systems based on communication networks and which allow, in particular the implementation of closed loop dis...
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ISBN:
(纸本)9780769529752
the message scheduling is an essential mechanism in the context of Nerworked Control systems (NCS) which are systems based on communication networks and which allow, in particular the implementation of closed loop distributed control applications. the scheduling of the messages of the flows of these closed loop distributed applications strongly influences the stability of these applications. the message scheduling is, in several networks, mainly based on fixed (static) priorities associated to the messages (for example the network CAN). In previous works, we have shown that the static priority scheme has intrinsic limitations and so, we propose in this paper in order to overcome these limitations, the concept of hybrid (hierarchical) priority. Different hybrid priority schemes are presented and evaluated with respect to the stability performances of the closed loop distributed process control applications. We show, in particular the advantage of a scheduling based on a scheme "hybrid priority + time strategy".
Cloud computing has become increasingly popular due to deployment of cloud solutions that will enable enterprises to cost reduction and more operational flexibility. Reliability is a key metric for assessing performan...
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ISBN:
(纸本)9780769550886
Cloud computing has become increasingly popular due to deployment of cloud solutions that will enable enterprises to cost reduction and more operational flexibility. Reliability is a key metric for assessing performance in such systems. Fault tolerance methods are extensively used to enhance reliability in Cloud computingsystems (CCS). However, these methods impose extra hardware and/or software cost. Proper resource allocation is an alternative approach which can significantly improve system reliability without any extra overhead. On the other hand, contemplating reliability irrespective of energy consumption and Quality of Service (QoS) requirements is not desirable in CCSs. In this paper, an analytical model to analyze system reliability besides energy consumption and QoS requirements is introduced. Based on the proposed model, a new online resource allocation algorithm to find the right compromise between system reliability and energy consumption while satisfying QoS requirements is suggested. the algorithm is a new swarm intelligence technique based on imperialist competition which elaborately combines the strengths of some well-known meta-heuristic algorithms with an effective fast local search. A wide range of simulation results, based on real data, clearly demonstrate high efficiency of the proposed algorithm.
Graphics processing units (GPUs) are capable of achieving remarkable performance improvements for a broad range of applications. However, they have not been widely adopted in embeddedsystems and mobile devices as acc...
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ISBN:
(纸本)9780769550886
Graphics processing units (GPUs) are capable of achieving remarkable performance improvements for a broad range of applications. However, they have not been widely adopted in embeddedsystems and mobile devices as accelerators mainly due to their relatively higher power consumption compared withembedded microprocessors. In this work, we conduct a comprehensive analysis regarding the feasibility and potential of accelerating applications using GPUs in low-power domains. We use two different categories of benchmarks: (1) the Level 3 BLAS subroutines, and (2) the computer vision algorithms, i.e., mean shift image segmentation and scale-invariant feature transform (SIFT). We carried out our experiments on the Nvidia CARMA development kit, which consists of a Nvidia Tegra 3 quad-core CPU and a Nvidia Quadro 1000M GPU. It is found that the GPU can deliver a remarkable performance speedup compared withthe CPU while using a significantly less energy for most benchmarks. Further we propose a hybrid approach to developing applications on platform with GPU accelerators. this approach optimally distributes workload between the parallel GPU and the sequential CPU to achieve the best performance while using the least energy.
this paper presents an implementation of feedback control strategy on distributed static scheduling. the static schedule is created taking into account the average execution times of the tasks. Feedback control algori...
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ISBN:
(纸本)0769523463
this paper presents an implementation of feedback control strategy on distributed static scheduling. the static schedule is created taking into account the average execution times of the tasks. Feedback control algorithm handles the unestimated dynamic behaviors in the system and keeps the performance at a desired level. the approach of feedback control supporting static scheduling yields more flexible scheduling, low scheduling overhead and better resource utilization while preserving the real-time constraints.
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