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Ismail Ababneh – One of the best experts on this subject based on the ideXlab platform.

  • A New Compacting Non-Contiguous Processor Allocation Algorithm for 2D Mesh Multicomputers
    Journal of Information Technology Research, 2015
    Co-Authors: Ismail Ababneh, Saad Bani-mohammad, Mohammad Yassen

    Abstract:

    In non-contiguous Allocation, a job Request can be split into smaller parts that are allocated possibly non-adjacent free sub-meshes rather than always waiting until a single sub-mesh of the Requested size and shape is available. Lifting the contiguity condition is expected to reduce processor fragmentation and increase system utilization. However, the distances traversed by messages can be long, and as a result the communication overhead, especially contention, is likely to increase. The extra communication overhead depends on how the Allocation Request is partitioned and assigned to free sub-meshes. In this paper, a new non-contiguous processor Allocation strategy, referred to as Compacting Non-Contiguous Processor Allocation Strategy CNCPA, is suggested for the 2D mesh multicomputers. In the proposed strategy, a job is compacted into free locations. The selection of the free locations has for goal leaving large free sub-meshes in the system. To evaluate the performance improvement achieved by the proposed strategy and compare it against well-known existing non-contiguous Allocation strategies, the authors conducted extensive simulation experiments. The results show that the proposed strategy can improve performance in terms of job turnaround times and system utilization.

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  • The effect of communication on the performance of Allocation Request shape changes in 2D mesh-connected multicomputers
    International Journal of Parallel Emergent and Distributed Systems, 2012
    Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Saad Bani-mohammad, Mohammad M Hamed

    Abstract:

    Contiguous Allocation in multicomputers is useful for security and accounting reasons. In mesh-connected systems, each job is allocated an exclusive submesh of processors, and the allocated submesh has the same shape and size as that Requested by the job. Because of this size and shape constraint, contiguous Allocation typically suffers from high processor fragmentation. Processor fragmentation can be reduced by considering contiguous Allocation to all possible Request shapes, while maintaining contiguity. However, Request shape modification can influence communication overhead. In this paper, we study the effect of Request shape modification on communication overhead and performance in 2D mesh-connected multicomputers, where several common communication patterns are simulated in detail. The simulation results based on both synthetic and real workload models show that permitting all Request shape changes can improve system performance substantially. For example, it improves the performance of first-fit Allocation by up to about 60% in terms of average job turnaround time.

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  • effects of Allocation Request shape changes on performance in 2d mesh connected multicomputers
    Computer and Information Technology, 2010
    Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Mohammad M Hamed, Saad Banimohammad

    Abstract:

    Contiguous Allocation in multicomputers is useful for security and accounting reasons. In mesh-connected systems, it allocates each job an exclusive submesh of processors, and the allocated submesh has the same shape and size as that Requested by the job. Because of this size and shape constraint, contiguous Allocation typically suffers from high processor fragmentation. Processor fragmentation can be reduced by considering contiguous Allocation to all possible Request shapes, while maintaining contiguity. However, Request shape modification can influence communication overhead. In this paper, we study the effect of Request shape modification on communication overhead and performance in two-dimensional mesh-connected multicomputers, where several common communication patterns are simulated in detail. The simulation results show that permitting all Request shape changes can improve system performance substantially. For example, it improves the performance of first-fit Allocation by up to 46% in terms of average job turnaround time.

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Saad Bani-mohammad – One of the best experts on this subject based on the ideXlab platform.

  • A New Compacting Non-Contiguous Processor Allocation Algorithm for 2D Mesh Multicomputers
    Journal of Information Technology Research, 2015
    Co-Authors: Ismail Ababneh, Saad Bani-mohammad, Mohammad Yassen

    Abstract:

    In non-contiguous Allocation, a job Request can be split into smaller parts that are allocated possibly non-adjacent free sub-meshes rather than always waiting until a single sub-mesh of the Requested size and shape is available. Lifting the contiguity condition is expected to reduce processor fragmentation and increase system utilization. However, the distances traversed by messages can be long, and as a result the communication overhead, especially contention, is likely to increase. The extra communication overhead depends on how the Allocation Request is partitioned and assigned to free sub-meshes. In this paper, a new non-contiguous processor Allocation strategy, referred to as Compacting Non-Contiguous Processor Allocation Strategy CNCPA, is suggested for the 2D mesh multicomputers. In the proposed strategy, a job is compacted into free locations. The selection of the free locations has for goal leaving large free sub-meshes in the system. To evaluate the performance improvement achieved by the proposed strategy and compare it against well-known existing non-contiguous Allocation strategies, the authors conducted extensive simulation experiments. The results show that the proposed strategy can improve performance in terms of job turnaround times and system utilization.

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  • The effect of communication on the performance of Allocation Request shape changes in 2D mesh-connected multicomputers
    International Journal of Parallel Emergent and Distributed Systems, 2012
    Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Saad Bani-mohammad, Mohammad M Hamed

    Abstract:

    Contiguous Allocation in multicomputers is useful for security and accounting reasons. In mesh-connected systems, each job is allocated an exclusive submesh of processors, and the allocated submesh has the same shape and size as that Requested by the job. Because of this size and shape constraint, contiguous Allocation typically suffers from high processor fragmentation. Processor fragmentation can be reduced by considering contiguous Allocation to all possible Request shapes, while maintaining contiguity. However, Request shape modification can influence communication overhead. In this paper, we study the effect of Request shape modification on communication overhead and performance in 2D mesh-connected multicomputers, where several common communication patterns are simulated in detail. The simulation results based on both synthetic and real workload models show that permitting all Request shape changes can improve system performance substantially. For example, it improves the performance of first-fit Allocation by up to about 60% in terms of average job turnaround time.

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  • CIT – Effects of Allocation Request Shape Changes on Performance in 2D Mesh-Connected Multicomputers
    2010 10th IEEE International Conference on Computer and Information Technology, 2010
    Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Mohammad M Hamed, Saad Bani-mohammad

    Abstract:

    Contiguous Allocation in multicomputers is useful for security and accounting reasons. In mesh-connected systems, it allocates each job an exclusive submesh of processors, and the allocated submesh has the same shape and size as that Requested by the job. Because of this size and shape constraint, contiguous Allocation typically suffers from high processor fragmentation. Processor fragmentation can be reduced by considering contiguous Allocation to all possible Request shapes, while maintaining contiguity. However, Request shape modification can influence communication overhead. In this paper, we study the effect of Request shape modification on communication overhead and performance in two-dimensional mesh-connected multicomputers, where several common communication patterns are simulated in detail. The simulation results show that permitting all Request shape changes can improve system performance substantially. For example, it improves the performance of first-fit Allocation by up to 46% in terms of average job turnaround time.

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Eduardo Tovar – One of the best experts on this subject based on the ideXlab platform.

  • an implicit gts Allocation mechanism in ieee 802 15 4 for time sensitive wireless sensor networks theory and practice
    Real-time Systems, 2008
    Co-Authors: Anis Koubaa, Eduardo Tovar, Mário Alves, Andre Cunha

    Abstract:

    Timeliness guarantee is an important feature of the recently standardized IEEE 802.15.4 protocol, turning it quite appealing for Wireless Sensor Network (WSN) applications under timing constraints. When operating in beacon-enabled mode, this protocol allows nodes with real-time requirements to allocate Guaranteed Time Slots (GTS) in the contention-free period. The protocol natively supports explicit GTS Allocation, i.e. a node allocates a number of time slots in each superframe for exclusive use. The limitation of this explicit GTS Allocation is that GTS resources may quickly disappear, since a maximum of seven GTSs can be allocated in each superframe, preventing other nodes to benefit from guaranteed service. Moreover, the GTS may be underutilized, resulting in wasted bandwidth. To overcome these limitations, this paper proposes i-GAME, an implicit GTS Allocation Mechanism in beacon-enabled IEEE 802.15.4 networks. The Allocation is based on implicit GTS Allocation Requests, taking into account the traffic specifications and the delay requirements of the flows. The i-GAME approach enables the use of one GTS by multiple nodes, still guaranteeing that all their (delay, bandwidth) requirements are satisfied. For that purpose, we propose an admission control algorithm that enables to decide whether to accept a new GTS Allocation Request or not, based not only on the remaining time slots, but also on the traffic specifications of the flows, their delay requirements and the available bandwidth resources. We show that our approach improves the bandwidth utilization as compared to the native explicit Allocation mechanism defined in the IEEE 802.15.4 standard. We also present some practical considerations for the implementation of i-GAME, ensuring backward compatibility with the IEEE 801.5.4 standard with only minor add-ons. Finally, an experimental evaluation on a real system that validates our theoretical analysis and demonstrates the implementation of i-GAME is also presented.

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  • ECRTS – i-GAME: an implicit GTS Allocation mechanism in IEEE 802.15.4 for time-sensitive wireless sensor networks
    18th Euromicro Conference on Real-Time Systems (ECRTS'06), 1
    Co-Authors: Anis Koubaa, Mário Alves, Eduardo Tovar

    Abstract:

    The IEEE 802.15.4 medium access control (MAC) protocol is an enabling technology for time sensitive wireless sensor networks thanks to its guaranteed-time slot (GTS) mechanism in the beacon-enabled mode. However, the protocol only supports explicit GTS Allocation, i.e. a node allocates a number of time slots in each superframe for exclusive use. The limitation of this explicit GTS Allocation is that GTS resources may quickly disappear, since a maximum of seven GTSs can be allocated in each superframe, preventing other nodes to benefit from guaranteed service. Moreover, the GTSs may be only partially used, resulting in wasted bandwidth. To overcome these limitations, this paper proposes i-GAME, an implicit GTS Allocation mechanism in beacon-enabled IEEE 802.15.4 networks. The Allocation is based on implicit GTS Allocation Requests, taking into account the traffic specifications and the delay requirements of the flows. The i-GAME approach enables the use of a GTS by multiple nodes, while all their (delay, bandwidth) requirements are still satisfied. For that purpose, we propose an admission control algorithm that enables to decide whether to accept a new GTS Allocation Request or not, based not only on the remaining time slots, but also on the traffic specifications of the flows, their delay requirements and the available bandwidth resources. We show that our proposal improves the bandwidth utilization compared to the explicit Allocation used in the IEEE 802.15.4 protocol standard. We also present some practical considerations for the implementation of i-GAME, ensuring backward compatibility with the IEEE 801.5.4 standard with only minor add-ons.

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