This paper proposes an optimistic data consistency method according to the question about data dependence in data consistency. In the method, data object is partitioned into data blocks by fixed size as the basic unit...
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This paper proposes an optimistic data consistency method according to the question about data dependence in data consistency. In the method, data object is partitioned into data blocks by fixed size as the basic unit of data management. Updates are compressed by Bloom filter technique and propagated in double-path. Negotiation algorithms detect and reconcile update conflicts, and dynamic data management algorithms accommodate dynamic data processing. The results of the performance evaluation show that it is an efficient method to achieve consistency, good dynamic property, and strong robustness when choosing the size of data block appropriately. At the same time, a feasible way is put forward on how to choose appropriate data block size.
The features of simple description, small updates item and weak dependence are the main characteristics of updates of key-attributes in P2P systems. Accordingly, an optimistic data consistency maintenance method based...
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The features of simple description, small updates item and weak dependence are the main characteristics of updates of key-attributes in P2P systems. Accordingly, an optimistic data consistency maintenance method based on key-attributes is proposed. In the method, the update of key-attributes is separated from user update requests. Key-Updates are propagated by latency-overlay update propagation model, that is, updates are always propagated to the nodes having maximum or minimum latency, and assured and uncertain propagation paths of updates are all taken into account. Based on classifying key-update conflicts, a double-level reconciling mechanism including buffer preprocessing and update-log processing is applied to detect and reconcile conflicts, and then conflicts are solved by policies as last-writer-win and divide-and-rule. Lastly, update-log management method and maintenance method brought by node failure and network partitioning are discussed for the above is deployed based on the information storied in update-log. Delaying key-attributes updates cannot occur by the optimistic disposal method, and then it cannot depress efficiency of resource location based on key-attributes, which adapts well to P2P systems for Internet. The simulation results show that it is an effective optimistic data consistency maintenance method, achieving good consistency overhead, resource location and resource access overhead, and having strong robustness.
This chapter presents a formalization of functional and behavioural requirements, and a refinement of requirements to a design for CoCoME using the Relational Calculus of Object and Component Systems (rCOS). We give a...
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Nowadays, weakly hard real-time is attracted in the research of real-time system. Existing weakly hard real-time scheduling algorithms cannot guarantee the meeting ratio of executing sequence of which the length is la...
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Nowadays, weakly hard real-time is attracted in the research of real-time system. Existing weakly hard real-time scheduling algorithms cannot guarantee the meeting ratio of executing sequence of which the length is larger than fixed window-size. Therefore, this paper, based on the (m, p) constraint, proposes an algorithm which is named as CDBS (cut-down based scheduling). Since the discrimination of the satisfiability of (m, p) constraint needs to go over the whole executing sequence of the task, it's very difficult and infeasible. For this reason, this paper brings an efficient algorithm of cutting down the sequence, proves the correctness of the algorithm. We use proper data structures so that the complexity of judgment is not relevant to the length of sequence. Experiments show the efficiency. Furthermore, we compare CDBS with other classical algorithms, such as EDF, DBP, DWCS, and the results show its competence.
Due to the characteristics of stream applications and the insufficiency of conventional processors when running stream programs, stream processors which support data-level parallelism become the research hotspot. This...
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Due to the characteristics of stream applications and the insufficiency of conventional processors when running stream programs, stream processors which support data-level parallelism become the research hotspot. This paper presents two means, stream partition (SP) and stream compression (SC), to optimize streams on Imagine. The results of simulation show that SP and SC can make stream applications take full advantage of the parallel clusters, pipelines and three-level memory hierarchy of the Imagine processor, and then reduce the execution time of stream programs.
The goal of the least areas path problem (LAPP) is to find a path traversing through a given region covered by a set of areas with any arbitrary shape, between a given pair of points and with the property that each po...
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The goal of the least areas path problem (LAPP) is to find a path traversing through a given region covered by a set of areas with any arbitrary shape, between a given pair of points and with the property that each point on the path is covered by the least areas. Different the weighted region optimal path problem, the LAPP asks for the cost of each step in path is as low as possible. Based on the relationship between boundaries of sub-regions and the least areas path, we can transform this continuous-domain problem to a discrete one by calculating the coverage of curves of sub-regionspsila boundaries. Depending on binary-search and breadth-first-search, an efficient and fast algorithm was devised for solving the LAPP.
Sybil attack is a network threat introduced by one or more malicious nodes to declare numerous illegal identifies to confuse or even collapse the network applications. A new detection mechanism, called CRSD, is propos...
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ISBN:
(纸本)9781424441969
Sybil attack is a network threat introduced by one or more malicious nodes to declare numerous illegal identifies to confuse or even collapse the network applications. A new detection mechanism, called CRSD, is proposed for static wireless sensor networks, which takes use of the received signal strength (RSS) to infer the distance between two identities and further determines the positions relation of the interesting identities by use of the RSS information from multiple neighbor nodes, e.g., via node cooperation. A Sybil attack is detected when two or more different identities have almost the same position. The analysis and simulation results show that, first, Sybil attack deteriorates the system performance significantly and second, CRSD can detect such attack in most cases, thus protecting the overall performance effectively.
The Cell processor is a typical heterogeneous multi-core processor, which owns powerful computing capability. But we are facing the challenges of 'memory wall' in developing parallel applications, such as, lim...
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The Cell processor is a typical heterogeneous multi-core processor, which owns powerful computing capability. But we are facing the challenges of 'memory wall' in developing parallel applications, such as, limited capacity of local memory, limited memory bandwidth for multi-cores and the long latency for data communication. The DMA transfer mechanism is often used to hide the long latency and improve the effective usage of memory bandwidth. In the paper, we start with a series of DMA experimental tests in the context of the Cell processor architecture, and perform mathematical analysis to setup a unified formula on the average bandwidth of DMA by means of exponential fitting, which describes that SPE amount and DMA block size take main effects on DMA bandwidth in quantity. With the supports of the DMA performance formula, we perform 4 types of memory optimization in the process of parallelizing the SWIM benchmark program into a multi-core version. We take Sony PlayStation 3 (PS3) as our test-bed. For SWIM benchmark, with 6 SPE cores, we obtain over 13 times of speedup compared to single PPE, and 3.3 to 6.18 times to AMD and Intel CPU.
PSL is a kind of temporal logic which uses SEREs as additional formula constructs. We present a variant of PSL, namely APSL, which replaces SEREs with finite automata. APSL and PSL are of the exactly same expressivene...
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PSL is a kind of temporal logic which uses SEREs as additional formula constructs. We present a variant of PSL, namely APSL, which replaces SEREs with finite automata. APSL and PSL are of the exactly same expressiveness. In this paper, we extend the LTL symbolic model checking algorithm to that of APSL, and present a tableau based APSL verification approach. Moreover, we show how to implement this algorithm via the BDD based symbolic approach.
In the field of RNA secondary structure prediction, the Zuker algorithm is one of the most popular methods using free energy minimization. However, general-purpose computers including parallel computers or multi-core ...
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In the field of RNA secondary structure prediction, the Zuker algorithm is one of the most popular methods using free energy minimization. However, general-purpose computers including parallel computers or multi-core computers exhibit parallel efficiency of no more than 50% on Zuker. FPGA chips provide a new approach to accelerate the Zuker algorithm by exploiting fine-grained custom design. Zuker shows complicated data dependences, in which the dependence distance is variable, and the dependence direction is also across two dimensions. We propose a systolic array structure including one master PE and multiple slave PEs for fine grain hardware implementation on FPGA. We exploit data reuse schemes to reduce the need to load energy matrices from external memory. We also propose several methods to reduce energy table parameter size by 85%. To our knowledge, our implementation with 16 PEs is the only FPGA accelerator implementing the complete Zuker algorithm. The experimental results show a factor of 14 speedup over the ViennaRNA-1.6.5 software for 2981-residue RNA sequence running on a PC platform with Pentium 4 2.6 GHz CPU.
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