the EU-funded XtreemOS project implements a Linux-based grid operating system (OS), exploiting resources of virtual organizations through the standard POSIX interface. the Object Sharing Service (OSS) of XtreemOS addr...
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ISBN:
(纸本)9780889867741
the EU-funded XtreemOS project implements a Linux-based grid operating system (OS), exploiting resources of virtual organizations through the standard POSIX interface. the Object Sharing Service (OSS) of XtreemOS addresses the challenges of transparent data sharing for distributed applications running in grids. We focus on the problem of handling consistency of replicated data in wide area networks in the presence of failures. the software architecture we propose interweaves concepts from transactional memory and peer-to-peer systems. Speculative transactions relieve programmers from complicated lock management. Super-peer-based overlay networks improve scalability and distributed hash tables speed up data search. OSS replicates objects to improve reliability and performance. In case of severe faults, the XtreemOS grid checkpointing service will support OSS. In this paper we describe the software architecture of OSS, design decisions, and evaluation results of preliminary experiments with a multi-user 3D virtual world.
Volunteer computing projects use donated CPU time to solve problems that would otherwise be too computationally intensive to solve. the donated CPU time comes from computers whose owners install a volunteer computing ...
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ISBN:
(纸本)9780889867741
Volunteer computing projects use donated CPU time to solve problems that would otherwise be too computationally intensive to solve. the donated CPU time comes from computers whose owners install a volunteer computing client program on their computer, allowing a project to use the computer's idle time. the low participation rate in volunteer computing and the increasing number of volunteer computing projects make improvements that more effectively use the donated CPU cycles very important. Past work showed that using certain task retrieval policies could increase the number of tasks volunteer computing clients complete. However, the past work assumed that the volunteered computers had a single CPU and the task retrieval methods that resulted in more completed tasks required the client to be connected to the Internet more often than the other policies. We simulated the task retrieval policies for computers with multi-core CPUs and found that in most cases, the multi-core architecture can lead to a slightly greater than linear increase in the number of tasks that the clients complete, relative to the number of cores the computer running the client has. Additionally, the multi-core architecture can reduce the performance gap between the best and worst performing policies significantly, affecting which policies are used.
Single node failures represent more than 85% of all node failures[7] in the today's large communication networks such as the Internet. Also, these node failures are usually transient. Consequently, having the rout...
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ISBN:
(纸本)9780889867741
Single node failures represent more than 85% of all node failures[7] in the today's large communication networks such as the Internet. Also, these node failures are usually transient. Consequently, having the routing paths globally recomputed does not pay off since the failed nodes recover fairly quickly, and the recomputed routing paths need to be discarded. Instead, we develop algorithms and protocols for dealing with such transient single node failures by suppressing the failure (instead of advertising it across the network), and routing messages to the destination via alternate paths that do not use the failed node. We compare our solution to that of [11], which also discusses such a proactive recovery scheme for handling transient node failures. We show that our algorithms are faster by an order of magnitude while our paths are equally good. We show via simulation results that our paths are usually within 15% of the optimal for randomly generated graph with 100-1000 nodes.
Timeliness is an important issue for video based surveillance and is often quantified by the delay between the time of availability of image frames from cameras and completion of their processing. Most existing commer...
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ISBN:
(纸本)9780889867741
Timeliness is an important issue for video based surveillance and is often quantified by the delay between the time of availability of image frames from cameras and completion of their processing. Most existing commercial video surveillance systems focus on the issues of efficient storage and retrieval, remote monitoring, data streaming, forensics and limited real-time analysis - but not explicitly on the timeliness issues of large scale online analysis vis-a-vis resource utilization. In this paper we present a new load distribution strategy for on-line, large scale video data processing clusters that are used as an aid to manual surveillance. We propose a novel approach for fine grained load balancing, modeled as a minimization of average completion time problem. the proposed approach is robust in the sense that it is not dependent on the estimates of future loads or on the worst case execution requirements of the video processing load. Simulation results with real-life video surveillance data establish that for a desired timeliness in processing the data, our approach reduces the number of compute nodes by more than a factor of two, compared to systems without the load migration heuristics.
In order to fulfill the demands for increased performance / power ratio, most chip-vendors are deploying multicore processors to their product lines. Multicore processors are frequently deployed with multilevel cache ...
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ISBN:
(纸本)9780889867741
In order to fulfill the demands for increased performance / power ratio, most chip-vendors are deploying multicore processors to their product lines. Multicore processors are frequently deployed with multilevel cache memories. parallelthread execution in such a multicore system is difficult as it relates to cache sharing to achieve the best performance. Due to the increased execution time unpredictability, it becomes a challenge to support realtime applications on multicore systems with multilevel caches. Studies show that predictability can be improved using cache locking techniques. However, entire locking at level-1 cache may be inefficient for smaller data size (when compared withthe cache size). Also, way locking at level-1 cache is not permitted on some processors (like PowerPC 750GX), but way locking at level-2 cache is possible. By locking at level-2 cache, Xenon processor achieves the effect of using local storage by Cell SPEs. In this work, we simulate a multicore parallelcomputing system with two levels of caches to explore the impact of level-2 cache locking on the performance, power consumption, and predictability. Experimental results show that performance and predictability can be increased and power consumption can be decreased by adding a level-2 cache locking mechanism to an efficient cache sharing structure.
A stabilizing system guarantees that, regardless of the current configuration, the system reaches a legal configuration in a bounded number of steps and the system configuration remains legal thereafter. Whereas, a st...
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ISBN:
(纸本)9780889867741
A stabilizing system guarantees that, regardless of the current configuration, the system reaches a legal configuration in a bounded number of steps and the system configuration remains legal thereafter. Whereas, a stabilizing system that maintains no explicit variables in the processes of the system is referred to as an inherently stabilizing system, and hence all system states are legal by construction. Due to this attribute, inherently stabilizing systems are immune to transient faults and do not experience any delay due arbitrary system initialization. We view a fault that perturbs the system configuration but not the program as transient fault. Due to these features, inherently stabilizing distributed protocols for peer-to-peer, sensor and mobile networks are desirable. Hypercube, star networks and their variations that provide an increased degree of scalability have been initially design for parallel networks. However, their scalability and the presence of multiple disjoint paths in these topologies make them viable alternatives to existing peer-to-peer and sensor networks topologies. In this paper, we proposed an inherently stabilizing algorithm for delivering messages over all node-disjoint paths from a process to another in star networks. the proposed algorithm has numerous applications including VLSI layout, reliable networks routing, secure message transmission, and network survivability. the proposed routing algorithm is optimal with respect to its state space and lengths of the node-disjoint paths.
Currently, the computational needs of scientific applications have grown to levels where it is necessary to have computers with a very high degree of parallelism. the IBM Blue Gene/L can hold in excess of 200K process...
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ISBN:
(纸本)9780889867741
Currently, the computational needs of scientific applications have grown to levels where it is necessary to have computers with a very high degree of parallelism. the IBM Blue Gene/L can hold in excess of 200K processors and it has been designed for high performance. However, failures in this large system are a major concern, since it has been demonstrated that a failure will drastically decrease the performance of the system. Checkpointing and log schemes have been utilized to overcome these failures, however, it has been shown that these techniques are not as effective as desired. therefore, proactive failure detection and prediction has gained interest in the research community. In this study, we have collected the RAS event and Job logs from a large IBM Blue Gene/L over a three-month period. We have investigated the relationship among fatal and non-fatal events withthe aim of proactive failure prediction. Based on our observations, we have developed a scheme for predicting fatal events based on the spatial and temporal relation among fatal and nonfatal events. We will show that with our scheme up to 84% of fatal events could be effectively predicted.
this book constitutes the refereed proceedings of the IFIP TC 10 Working conference on distributed and parallel Embedded systems, held at the 20th World Computer Congress inMilan, Italy on September 7-10, 2008. the IF...
ISBN:
(数字)9780387096612
ISBN:
(纸本)9780387096605
this book constitutes the refereed proceedings of the IFIP TC 10 Working conference on distributed and parallel Embedded systems, held at the 20th World Computer Congress inMilan, Italy on September 7-10, 2008. the IFIP series publishes state-of-the-art results in the sciences and technologies of information and communication. the scope of the series includes: foundations of computer science; software theory and practice; education; computer applications in technology; communication systems; systems modeling and optimization; information systems; computers and society; computer systems technology; security and protection in information processing systems; artificial intelligence; and human-computer interaction. Proceedings and post-proceedings of refereed internationalconferences in computer science and interdisciplinary fields are featured. these results often precede journal publication and represent the most current research. the principal aim of the IFIP series is to encourage education and the dissemination and exchange of information about all aspects of computing.
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