The Experts below are selected from a list of 8199 Experts worldwide ranked by ideXlab platform
Ismail Ababneh - One of the best experts on this subject based on the ideXlab platform.
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A New Compacting Non-Contiguous Processor Allocation Algorithm for 2D Mesh Multicomputers
Journal of Information Technology Research, 2015Co-Authors: Ismail Ababneh, Saad Bani-mohammad, Mohammad YassenAbstract: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, 2012Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Saad Bani-mohammad, Mohammad M HamedAbstract: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, 2010Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Mohammad M Hamed, Saad BanimohammadAbstract: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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CIT - Effects of Allocation Request Shape Changes on Performance in 2D Mesh-Connected Multicomputers
2010 10th IEEE International Conference on Computer and Information Technology, 2010Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Mohammad M Hamed, Saad Bani-mohammadAbstract: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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Availability-based noncontiguous processor Allocation policies for 2D mesh-connected multicomputers
Journal of Systems and Software, 2008Co-Authors: Ismail AbabnehAbstract:Various contiguous and noncontiguous processor Allocation policies have been proposed for mesh-connected multicomputers. Contiguous Allocation suffers from high external processor fragmentation because it requires that the processors allocated to a parallel job be contiguous and have the same topology as the multicomputer. The goal of lifting the contiguity condition in noncontiguous Allocation is reducing processor fragmentation. However, this can increase the communication overhead because the distances traversed by messages can be longer, and messages from different jobs can interfere with each other by competing for communication resources. The extra communication overhead depends on how the Allocation Request is partitioned and mapped to free processors. In this paper, we investigate a new class of noncontiguous Allocation schemes for two-dimensional mesh-connected multicomputers. These schemes are different from previous ones in that Request partitioning is based on the submeshes available for Allocation. The available submeshes selected for Allocation to a job are such that a high degree of contiguity among their processors is achieved. The proposed policies are compared to previous noncontiguous policies using detailed simulations, where several common communication patterns are considered. The results show that the proposed policies can reduce the communication overhead and improve performance substantially.
Saad Bani-mohammad - One of the best experts on this subject based on the ideXlab platform.
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A New Compacting Non-Contiguous Processor Allocation Algorithm for 2D Mesh Multicomputers
Journal of Information Technology Research, 2015Co-Authors: Ismail Ababneh, Saad Bani-mohammad, Mohammad YassenAbstract: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, 2012Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Saad Bani-mohammad, Mohammad M HamedAbstract: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, 2010Co-Authors: Ismail Ababneh, Wail Mardini, Hilal Alawneh, Mohammad M Hamed, Saad Bani-mohammadAbstract: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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A new processor Allocation strategy with a high degree of contiguity in mesh-connected multicomputers
Simulation Modelling Practice and Theory, 2007Co-Authors: Saad Bani-mohammad, M. Ould-khaoua, Ismail AbabnehAbstract:Abstract Relaxing the contiguity condition in non-contiguous Allocation can reduce processor fragmentation and increase processor utilization. However, communication overhead could increase due to the potential increase in message distances. The communication overhead depends on how the Allocation Request is partitioned and allocated to free sub-meshes. In this paper, a new non-contiguous processor Allocation strategy, referred to as Greedy-Available-Busy-List (GABL for short), is suggested for the mesh network, and is compared against the existing non-contiguous and contiguous Allocation strategies. To demonstrate the performance gains achieved by our proposed strategy, we have conducted simulation runs under the assumption of wormhole routing technique. The results have revealed that the new strategy can reduce communication overhead and considerably improve performance in terms of the job turnaround time, system utilization, and jobs finish time.
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AICCSA - An Efficient Processor Allocation Strategy that Maintains a High Degree of Contiguity among Processors in 2D Mesh Connected Multicomputers
2007 IEEE ACS International Conference on Computer Systems and Applications, 2007Co-Authors: Saad Bani-mohammad, Ismail Ababneh, M. Ould-khaoua, Lewis M. MackenzieAbstract:Two strategies are used for the Allocation of jobs to processors connected by mesh topologies: contiguous Allocation and non-contiguous Allocation. In noncontiguous Allocation, a job Request can be split into smaller parts that are allocated to 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 increased. The extra communication overhead depends on how the Allocation Request is partitioned and assigned to free sub-meshes. This paper presents a new noncontiguous Allocation algorithm, referred to as greedy-available-busy-list (GABL for short), which can decrease the communication overhead among processors allocated to a given job. The simulation results show that the new strategy can reduce the communication overhead and substantially improve performance in terms of parameters such as job turnaround time and system utilization. Moreover, the results reveal that the shortest- service-demand-first (SSD) scheduling strategy is much better than the first-come-first-served (FCFS) scheduling strategy.
Eduardo Tovar - One of the best experts on this subject based on the ideXlab platform.
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an implicit gts Allocation mechanism in ieee 802 15 4 for time sensitive wireless sensor networks theory and practice
Real-time Systems, 2008Co-Authors: Anis Koubaa, Mário Alves, Eduardo Tovar, Andre CunhaAbstract: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), 1Co-Authors: Anis Koubaa, Mário Alves, Eduardo TovarAbstract: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.
Anis Koubaa - One of the best experts on this subject based on the ideXlab platform.
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an implicit gts Allocation mechanism in ieee 802 15 4 for time sensitive wireless sensor networks theory and practice
Real-time Systems, 2008Co-Authors: Anis Koubaa, Mário Alves, Eduardo Tovar, Andre CunhaAbstract: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), 1Co-Authors: Anis Koubaa, Mário Alves, Eduardo TovarAbstract: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.
Yves Albrieux - One of the best experts on this subject based on the ideXlab platform.
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A New Dynamic IPC-Memory Allocator Based on a Paging Approach
2013Co-Authors: Ridha Benosman, Kamel Barkaoui, Yves AlbrieuxAbstract:In a distributed system, multiple processes can communicate and exchange data. These processes can be either local (on the same host machine), or remote (on different ones). The POSIX IPC standard provides a set of mechanisms (such as shared memory, message queues and semaphores) for data sharing and synchronization between local processes. In particular, the shared memory mechanism allows multiple local processes/threads to share the same address space. However, this mechanism only allows the sharing of data that belongs to the basic types (such as integer, float, char, ...) and does not support natively the share of pointers. In addition, the shared memory area presents in the form of a contiguous space, which can lead to fragmentation (internal/external) and compaction problems during use. In this paper, we present a new dynamic shared memory allocator (DSMA) addressing these limitations. Other aspects are also taken into account by the allocator, such as portability, performance (response time for an Allocation Request) or the consistency of shared data in a concurrent access to the same shared memory space. The allocator is in the form of a C/C++ API, compiled and tested on three operating systems: Linux, Windows and Mac-OS.
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HPCS - A new dynamic IPC-memory allocator based on a paging approach
2013 International Conference on High Performance Computing & Simulation (HPCS), 2013Co-Authors: Ridha Benosman, Kamel Barkaoui, Yves AlbrieuxAbstract:In a distributed system, multiple processes can communicate and exchange data. These processes can be either local (on the same host machine), or remote (on different ones). The POSIX IPC standard provides a set of mechanisms (such as shared memory, message queues and semaphores) for data sharing and synchronization between local processes. In particular, the shared memory mechanism allows multiple local processes/threads to share the same address space. However, this mechanism only allows the sharing of data that belongs to the basic types (such as integer, float, char, ...) and does not support natively the share of pointers. In addition, the shared memory area presents in the form of a contiguous space, which can lead to fragmentation (internal/external) and compaction problems during use. In this paper, we present a new dynamic shared memory allocator (DSMA) addressing these limitations. Other aspects are also taken into account by the allocator, such as portability, performance (response time for an Allocation Request) or the consistency of shared data in a concurrent access to the same shared memory space. The allocator is in the form of a C/C++ API, compiled and tested on three operating systems: Linux, Windows and Mac-OS.
