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Recently, structured P2P (Peer-to-Peer) system has become more and more popular. However, P2P systems' large scale and high dynamics have brought a great challenge to data availability and accessing performance. Redundancy techniques are used to solve these problems. However, in structured P2P systems, due to the consistent hash, the overlay network could not match underlying physical network well...
Nowadays, datasets grow enormously both in size and complexity. One of the key issues confronted by large-scale dataset analysis is how to adapt systems to new, unprecedented query loads. Existing systems nail down the data organization scheme once and for all at the beginning of the system design, thus inevitably will see the performance goes down when user requirements change. In this paper, we...
Recently, the CUDA technology has been used to accelerate many computation demanding tasks. For example, in our previous work we have shown how CUDA technology can be employed to accelerate the process of Linear Temporal Logic (LTL) Model Checking. While the raw computing power of a CUDA enabled device is tremendous, the applicability of the technology is quite often limited to small or middle-sized...
This paper describes an extension of the Consensus Service proposed by Guerraoui and Schiper. The objective is to provide a standard way to implement agreement protocols resilient to Byzantine faults using an intrusion tolerant service built upon virtual machines technology. This is achieved through the implementation of a Generic Consensus Service (GCS). GCS separates specificities of different agreement...
Conventional privilege separation can effectively reduce the TCB size by granting privilege to only the privileged compartments. However, since they this approach relies on process isolation to ensure security assurance, malware exploiting against kernel components can easily compromise. Meanwhile, the frequent inter-process communications between separated processes inevitably incur notable overhead...
For some sensor network applications, the problem of sweep coverage, which periodically covers POIs (Points of Interest) to sense events, is of importance. How to schedule minimum number of mobile sensors to achieve the sweep coverage within specified sweep period is a challenging problem, especially when the POIs to be scanned exceeds certain scale and the speed of mobile sensor is limited. Therefore,...
To fully tap into the potential of heterogeneous machines composed of multicore processors and multiple accelerators, simple offloading approaches in which the main trunk of the application runs on regular cores while only specific parts are offloaded on accelerators are not sufficient. The real challenge is to build systems where the application would permanently spread across the entire machine,...
In this paper, we present a new heuristic that generates broadcast schemes in arbitrary networks. The heuristic gives optimal broadcast time for ring, tree and grid if the originator is on the corner. Extensive simulations show that our new heuristic outperforms the best known broadcast algorithms for two different network models representing Internet and ATM networks. It also allows to generate broadcast...
Participatory Sensing is an emerging application paradigm that leverages the growing ubiquity of sensor-capable smart phones to allow communities carry out wide-area sensing tasks, as a side-effect of people's everyday lives and movements. This paper proposes a decentralized infrastructure for supporting Participatory Sensing applications. It describes an architecture and a domain specific programming...
The importance of XPath in XML filtering systems has led to a significant body of research on improving the processing performance of XPath queries. Most of the work, however, has been in the context of a single processing core. Given the prevalence of multicore processors, we believe that a parallel approach can provide significant benefits for a number of application scenarios. In this paper we...
We have designed and implemented a scripting environment called "Kumoi" for managing collective VMs in a large-scale data center. Kumoi is unlike other scripting environments because it exploits strong typing with type inference and high-level description. Kumoi introduces several advancements, including treating virtual machines as first-class objects and decoupling the scripting model...
With the good properties of NAND flash memory such as small size, shock resistance, and low-power consumption, large capacity SSD (Solid State Disk) is anticipated to replace hard disk in high-end systems. However, the cost of NAND flash memory is still high to substitute for hard disk entirely. Using hard disk and NAND flash memory together as secondary storage is an alternative solution to provide...
A weak conjunctive predicate is a conjunction of local predicates that is evaluated under the Possibly modality. In this study, we have proposed a distributed on-line algorithm for detecting weak conjunctions of unstable predicates in dynamic systems. In the algorithm, a virtual network of a logical ring combined with computation trees is dynamically maintained using local variables to keep track...
This paper considers object-based distributed real-time systems within which objects provide system services to the real-time tasks. Each task is subject to a time/utility function (TUF) which determines the accrued utility of the task according to its completion time. One major problem in such systems is to place the objects onto the computing nodes so as to maximize the total accrued utility. Thus,...
The Interconnection networks are essential elements in current computing systems. For this reason, achieving the best network performance, even in congestion situations, has been a primary goal in recent years. In that sense, there exist several techniques focused on eliminating the main negative effect of congestion: the Head of Line (HOL) blocking. One of the most successful HOL blocking elimination...
Wireless sensor networks (WSNs) have received considerable attention in recent years as they have great potential for many distributed applications in different scenarios. Whatever the scenario, WSNs are actually connected to an external network, through which sensed information are passed to the Internet and control messages can reach the WSN. This paper presents Smart, a service model for integrating...
As supercomputers are being built from an ever increasing number of processing elements, the effort required to achieve a substantial fraction of the system peak performance is continuously growing. Tools are needed that give developers and computing center staff holistic indicators about the resource consumption of applications and potential performance pitfalls at scale. To use the full potential...
The fat-tree topology has become a popular choice for InfiniBand fabrics due to its inherent deadlock freedom, fault-tolerance and full bisection bandwidth. InfiniBand is used by more than 40% of the systems on the latest Top 500 list, and many of these systems are based on a fat-tree topology. However, the current InfiniBand fat-tree routing algorithm suffers from flaws that reduce its scalability...
Service availability and QoS, in terms of customer affecting performance metrics, is crucial for service systems. However, the increasing complexity in distributed service systems introduce hidden space for software faults, which undermine system availability, leading to fault or even down time. In this paper, we introduce a composition technique, Coordinated Selective Rejuvenation, to automate the...
The Map Reduce programming model simplifies large-scale data processing on commodity clusters by having users specify a map function that processes input key/value pairs to generate intermediate key/value pairs, and a reduce function that merges and converts intermediate key/value pairs into final results. Typical Map Reduce implementations such as Hadoop enforce barrier synchronization between the...
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