Task scheduling has been known to be one of the challenging issues in parallel and distributedcomputing. there have been many scheduling algorithms proposed for scheduling tasks onto unlimited number of processors, w...
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Task scheduling has been known to be one of the challenging issues in parallel and distributedcomputing. there have been many scheduling algorithms proposed for scheduling tasks onto unlimited number of processors, while, in practical situations, there are only a limited number of processors available. thus, the goal of this work is to propose several new features to vastly improve the already-efficient bounded-CPFD algorithm (Ahmad and Kwok, 1998). the proposed technique, instead of considering only parent processors when scheduling a task in the original bounded-CPFD algorithm, allows other processors to be considered as well. this heuristic intends to provide a better load balance among the processors in leading to a shorter overall schedule length by allowing potentially more task duplication. Results from an extensive simulation show significant performance improvement from the proposed techniques over the bounded-CPFD.
Various types of multimedia objects are distributed to peer computers (peers) in peer-to-peer (P2P) overlay networks. An application has to find target peers which can support enough quality of service (QoS) of target...
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Various types of multimedia objects are distributed to peer computers (peers) in peer-to-peer (P2P) overlay networks. An application has to find target peers which can support enough quality of service (QoS) of target multimedia objects. We discuss acquaintance relations of peers with respect to what objects each peer holds, is allowed to manipulate, and can grant access rights on. We discuss a charge-based flooding (CBF) algorithm to find target peers based on charge and acquaintance concepts so that areas in P2P overlay networks where target peers are expected to exist are more deeply searched. We evaluate the CBF algorithm compared with a traditional flooding algorithm in terms of the number of messages transmitted in networks.
distributed Denial-of-Service (DDoS) attack is one of the most serious threats to the Internet. Detecting DDoS at the source-end has many advantages over defense at the victim-end and intermediate-network. One of the ...
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distributed Denial-of-Service (DDoS) attack is one of the most serious threats to the Internet. Detecting DDoS at the source-end has many advantages over defense at the victim-end and intermediate-network. One of the main problems for source-end methods is the performance degradation brought by these methods, which discourages Internet service providers (ISPs) to deploy the defense system. We propose an efficient detection approach, which only requires limited fixed-length memory and low computation overhead but provides satisfying detection results. the low cost of defense is expected to attract more ISPs to join the defense. the experiments results show our approach is efficient and feasible for defense at the source-end
Computers of a non-dedicated cluster are often idle (users attend meetings, have lunch or coffee breaks) or lightly loaded (users carry out simple computations). these underutilized computers can be employed to execut...
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Computers of a non-dedicated cluster are often idle (users attend meetings, have lunch or coffee breaks) or lightly loaded (users carry out simple computations). these underutilized computers can be employed to execute parallel applications not only during weekends and at nights but also during office hours. thus, they have to be shared by parallel and sequential applications which could lead to the improvement of their execution performance. However, there is a lack of experimental study showing the behavior and performance of parallel and sequential applications executing concurrently on clusters. We present here the result of an experimental study into load balancing based scheduling of a mixture of parallel and sequential applications on a non-dedicated cluster.
To achieve fast packet classification, a hardware-based scheme, cross-producting recurrence (CPR), based on a formerly proposed cross-producting scheme is proposed. this scheme simplifies the classification procedure ...
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To achieve fast packet classification, a hardware-based scheme, cross-producting recurrence (CPR), based on a formerly proposed cross-producting scheme is proposed. this scheme simplifies the classification procedure and decrease the distinct combinations of fields by hierarchically decomposing the multi-dimensional space. In the new scheme, the multi-dimensional space is endowed with a hierarchical property which self-divides into several smaller subspaces, whereas the procedure of packet classification is translated into repeatedly searching for matching subspaces. the required storage of the proposed scheme is significantly reduced since the distinct fields of subspaces is controlled by a pre-defined configuration and can be much less than that of the filters. the experimental results demonstrate the effectiveness and scalability of the proposed scheme
the development of a parallel adaptive mesh refinement (AMR) scheme is described for solving the governing equations for multi-phase (gas-particle) core flows in solid propellant rocket motors (SRMs). An Eulerian form...
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the development of a parallel adaptive mesh refinement (AMR) scheme is described for solving the governing equations for multi-phase (gas-particle) core flows in solid propellant rocket motors (SRMs). An Eulerian formulation is used to describe the coupled motion between the gas and particle phases. A cell-centred upwind finite-volume discretization and the use of limited linear reconstruction, Riemann solver based flux functions for the gas and particle phases, and explicit multi-stage time-stepping allows for high solution accuracy and computational robustness. A Riemann problem is formulated for prescribing boundary data at the burning surface and a mesh adjustment algorithm has been implemented to adjust the multi-block quadrilateral mesh to the combustion interface. A flexible block-based hierarchical data structure is used to facilitate automatic solution-directed mesh adaptation according to physics-based refinement criteria. Efficient and scalable parallel implementations are achieved with domain decomposition on distributed memory multi-processor architectures. Numerical results are described to demonstrate the capabilities of the approach for predicting SRM core flows.
Grids technology enables the sharing and collaborating of wide variety of resources. To fully utilize these resources, effective discovery techniques are necessities. However, the complicated and heterogeneous charact...
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Grids technology enables the sharing and collaborating of wide variety of resources. To fully utilize these resources, effective discovery techniques are necessities. However, the complicated and heterogeneous characteristics of the grid resource make sharing and discovering a challenging issue. In this paper, we propose a comprehensive semantic-based resource discovery framework, which performs an effective searching according to the semantic properties of what is searched. In the framework, nodes are grouped into clusters according to some criteria. Resources are indexed and aggregated with a highly compressed format. the summarized index can act as network knowledge to guide routing in the network. Intra-cluster and inter-cluster routing strategies are proposed to support scalable and efficient searching. Results from simulation demonstrate that this architecture is very effective in grid resource discovery.
the session initiation protocol (SIP) will provide the signaling network in the next generation networks, such as UMTS and cdma2000. Here we study the traffic load generated by the use of this protocol from a methodol...
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the session initiation protocol (SIP) will provide the signaling network in the next generation networks, such as UMTS and cdma2000. Here we study the traffic load generated by the use of this protocol from a methodological point of view. We propose an analytical technique to simulate SIP finite state machine (FSM) in an IP network by means of the theory of queuing networks. Based on this approach, we derive a simple model which can be applied to different network scenarios for performance evaluation and engineering purposes. We conclude this study by showing some results about call dropping rate in a wireless access network.
the access control mechanisms are critical to ensure security in XML (extensible markup language). Several such mechanisms have been used or proposed; however, the notion of delegation in XML has not been studied in t...
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the access control mechanisms are critical to ensure security in XML (extensible markup language). Several such mechanisms have been used or proposed; however, the notion of delegation in XML has not been studied in the literature. In this paper, we propose an access control model encapsuling delegation authorization rules for XML documents that allow flexible data granularity and limited inference protection. Our access control policy specification is basically DTD-based. It can also be considered to be document-based
PageRank becomes the most well-known re-ranking technique of the search results. By its iterative computational nature, the computation takes much computing time and resource. Researchers have then devoted much attent...
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PageRank becomes the most well-known re-ranking technique of the search results. By its iterative computational nature, the computation takes much computing time and resource. Researchers have then devoted much attention in studying an efficient way to compute the PageRank scores of a very large Web graph. However, only a few of them focus on large-scale PageRank computation using parallel processing techniques. In this paper, we propose a partition-based parallel PageRank algorithm that can efficiently run on a low-cost parallel environment like the PC cluster. For comparison, we also study the other two known techniques, as well as propose an analytical discussion concerning I/O and synchronization cost, and memory usage. Experimental results with two Web graphs synthesized from the .th domain and the Stanford WebBase project are very promising.
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