1,824 research outputs found

    Automating the multiprocessing environment

    Get PDF
    An approach to automate the programming and operation of tree-structured networks of multiprocessor systems is discussed. A conceptual, knowledge-based operating environment is presented, and requirements for two major technology elements are identified as follows: (1) An intelligent information translator is proposed for implementating information transfer between dissimilar hardware and software, thereby enabling independent and modular development of future systems and promoting a language-independence of codes and information; (2) A resident system activity manager, which recognizes the systems capabilities and monitors the status of all systems within the environment, is proposed for integrating dissimilar systems into effective parallel processing resources to optimally meet user needs. Finally, key computational capabilities which must be provided before the environment can be realized are identified

    Validation of multiprocessor systems

    Get PDF
    Experiments that can be used to validate fault free performance of multiprocessor systems in aerospace systems integrating flight controls and avionics are discussed. Engineering prototypes for two fault tolerant multiprocessors are tested

    Problems related to the integration of fault tolerant aircraft electronic systems

    Get PDF
    Problems related to the design of the hardware for an integrated aircraft electronic system are considered. Taxonomies of concurrent systems are reviewed and a new taxonomy is proposed. An informal methodology intended to identify feasible regions of the taxonomic design space is described. Specific tools are recommended for use in the methodology. Based on the methodology, a preliminary strawman integrated fault tolerant aircraft electronic system is proposed. Next, problems related to the programming and control of inegrated aircraft electronic systems are discussed. Issues of system resource management, including the scheduling and allocation of real time periodic tasks in a multiprocessor environment, are treated in detail. The role of software design in integrated fault tolerant aircraft electronic systems is discussed. Conclusions and recommendations for further work are included

    LUNES: Agent-based Simulation of P2P Systems (Extended Version)

    Full text link
    We present LUNES, an agent-based Large Unstructured NEtwork Simulator, which allows to simulate complex networks composed of a high number of nodes. LUNES is modular, since it splits the three phases of network topology creation, protocol simulation and performance evaluation. This permits to easily integrate external software tools into the main software architecture. The simulation of the interaction protocols among network nodes is performed via a simulation middleware that supports both the sequential and the parallel/distributed simulation approaches. In the latter case, a specific mechanism for the communication overhead-reduction is used; this guarantees high levels of performance and scalability. To demonstrate the efficiency of LUNES, we test the simulator with gossip protocols executed on top of networks (representing peer-to-peer overlays), generated with different topologies. Results demonstrate the effectiveness of the proposed approach.Comment: Proceedings of the International Workshop on Modeling and Simulation of Peer-to-Peer Architectures and Systems (MOSPAS 2011). As part of the 2011 International Conference on High Performance Computing and Simulation (HPCS 2011

    A Rapid Heuristic for Scheduling Non-Preemptive Dependent Periodic Tasks onto Multiprocessor

    Get PDF
    International audienceWe address distributed real-time applications represented by systems of non-preemptive dependent periodic tasks. This system is described by an acyclic directed graph. Because the distribution and the scheduling of these tasks onto a multiprocessor is an NP-hard problem we propose a greedy heuristic to solve it. Our heuristic sequences three algorithms: assignment, unrolling, and scheduling. The tasks of the same, or multiple, periods are assigned to the same processor according to a mixed sort. Then, the initial graph of tasks is unrolled, i.e. each task is repeated according to the ratio between its period and the least common multiple of all periods of tasks. Finally, the tasks of the unrolled graph are distributed and scheduled onto the processors where they have been assigned. Then, we give the complexity of this heuristic, and we illustrate it with an example. A performance analysis comparing our heuristic with an optimal Branch and Cut algorithm concludes that our heuristic is effective in terms of scheduling success ratio and speed

    Partitioned EDF Scheduling in Multicore systems with Quality of Service constraints

    Get PDF
    International audienceIn this paper we study the partitioned EDF scheduling in a homogeneous multiprocessor environment with Quality of Service (QoS) constraints. The system considered here is a real-time multiprocessor system assumed to be powered by rechargeable batteries. We address the issue of how to best partition a set of firm real-time tasks that can occasionally skip one instance according to a predefined QoS threshold. The main goal is to minimize the energy consumption of the system while offering solutions with respect to transient energy starvation situations the system can experiment. The contribution of the paper is twofold. First, we present a schedulability analysis of firm multiprocessor task sets under QoS constraints. Second we propose new partitionning heuristics integrating skips. The evaluation is conducted from several points of view (minimization of the total processor number, maximization of the spare capacity on each processor)

    Diagnosis of static Topology MANETs in faulty environment

    Get PDF
    Mobile Ad-Hoc Networks (MANETs) are set of mobile nodes that communicates wirelessly without a centralized supporting system. Faulty nodes aect the reliable transmission of messages across the network. In this thesis we deal with the fault identication problem in static topology MANETs. A comparison based approach is used where a set of tasks is given to the nodes and outcomes are compared. Based on these comparisons the nodes are classied either as faulty or fault free. Our new diagnosis model is based on the spanning tree concept in which the testing of the nodes as well as the construction of the spanning tree takes place simultaneously. As a result of which the maintenance and the repairing overhead of the spanning tree is completely avoided thus reducing the number of messages exchanged. We have also developed a simulator which can be applied to a network with large number of nodes.We have carried out the simulation in-order to nd out the total number of messages exchanged and the total diagnosis time. On analysing the results we have seen that our model performs better than its previous counterparts. The correctness and complexity proofs are also being provided which also shows that our model performs better from a communication as well as latency viewpoint

    Quantitative Evaluation in Embedded System Design: Validation of Multiprocessor Multithreaded Architectures

    Get PDF
    International audienceAs levels of parallelism are becoming increasingly complex in multiprocessor architectures, GALS, and asynchronous circuits, methodologies and software tools are needed to verify their functional behavior (qualitative properties) and to predict their performance (quantitative properties). This paper presents the work currently done in the Multival project (pôle de compétitivité mondial Minalogic), in which verification and performance evaluation tools developed at INRIA and Saarland University are applied to three industrial architectures designed by Bull, CEA/Leti, and STMicroelectronics

    YARTISS: A Tool to Visualize, Test, Compare and Evaluate Real-Time Scheduling Algorithms

    Get PDF
    International audienceIn this paper, we present a free software written in Java, YARTISS, which is a real-time multiprocessor scheduling simulator. It is aimed at comparing user-customized algorithms with ones from the literature on real-time scheduling. This simulator is designed as an easy-to-use modular tool in which new modules can be added without the need to decompress, edit nor recompile existing parts. It can simulate the execution of a large number of concurrent periodic independent task sets on multiprocessor systems and generate clear visual results of the scheduling process (both schedules and tunable metrics presentations). Other task models are already implemented in the simulator, like graph tasks with precedence constraints and it is easily extensible to other task models. Moreover, YARTISS can simulate task sets in which energy consumption is a scheduling parameter in the same manner as Worst Case Execution Time (WCET)

    Schedulability Analysis for Directed Acyclic Graphs on Multiprocessor Systems at a Subtask Level

    Get PDF
    International audienceThis paper addresses the problem of scheduling parallel real- time tasks of Directed Acyclic Graph (DAG) model on multiprocessor systems. We propose a new scheduling method based on a subtask-level, which means that the schedulability decisions are taken based on the local temporal parameters of subtasks. This method requires modifying the subtasks to add more parameters which are necessary for the analysis, such as local offsets, deadlines and release jitters. Then we provide interference and workload analyses of DAG tasks, and we provide a schedulability test for any work conserving scheduling algorithm
    corecore