54356023
A monitoring sensor management system for grid environments
Large distributed systems, such as computational grids, require a large amount of monitoring data be collected for a variety of tasks, such as fault detection, performance analysis, performance tuning, performance prediction and scheduling. Ensuring that all necessary monitoring is turned on and that the data is being collected can be a very tedious and error-prone task. We have developed an agent-based system to automate the execution of monitoring sensors and the collection of event data.
11908873
Using high speed networks to enable distributed parallel image server systems
We describe the design and implementation of a distributed parallel storage system that uses high-speed ATM networks as a key element of the architecture. Other elements include a collection of network-based disk block servers, and an associated name server that provides some file system functionality. The implementation is based on user level software that runs on UNIX workstations. Both the architecture and the implementation are intended to provide for easy and economical scalability. This approach has yielded a data source that scales economically to very high speed. Target applications include online storage for both very large images and video sequences. This paper describes the architecture, and explores the performance issues of the current implementation.<<ETX>>
1586129
A network-aware distributed storage cache for data intensive environments
Modern scientific computing involves organizing, moving, visualizing, and analyzing massive amounts of data at multiple sites around the world. The technologies, the middleware services, and the architectures that are used to build useful high-speed, wide area distributed systems, constitute the field of data intensive computing. We describe an architecture for data intensive applications where we use a high-speed distributed data cache as a common element for all of the sources and sinks of data. This cache-based approach provides standard interfaces to a large, application-oriented, distributed, on-line, transient storage system. We describe our implementation of this cache, how we have made it "network aware ", and how we do dynamic load balancing based on the current network conditions. We also show large increases in application throughput by access to knowledge of the network conditions.
9722973
Monitoring Data Archives for Grid Environments
Developers and users of high-performance distributed systems often observe performance problems such as unexpectedly low throughput or high latency. To determine the source of these performance problems, detailed end-to-end monitoring data from applications, networks, operating systems, and hardware must be correlated across time and space. Researchers need to be able to view and compare this very detailed monitoring data from a variety of angles. To address this problem, we propose a relational monitoring data archive that is designed to efficiently handle high-volume streams of monitoring data. In this paper we present an instrumentation and monitoring event archive service that can be used to collect and aggregate detailed end-to-end monitoring information from distributed applications. This archive service is designed to be scalable and fault tolerant. We also show how the archive is based on the "Grid Monitoring Architecture" defined by the Global Grid Forum.
9094168
Microscopic examination of TCP flows over transatlantic links
Much of the recent research and development in the area of high-speed TCP is focused on the steady state behavior of TCP flows. However, our experience with the first research only transatlantic 2.5 Gbps Lambda link clearly demonstrates the need to focus on the initial stages of TCP. The work we present here examines the behavior of TCP flows at microscopic level over high-bandwidth long delay networks. This examination has led us to study the influence of the minute properties of the underlying network on bursty protocols such as TCP at these very high speeds combined with high latency. In this paper we briefly describe the requirements for such an extreme network environment to support high-speed TCP flows. We also present results collected using transatlantic links at iGrid2002 where we tuned various host parameters and used modified TCP stacks.
3126586
A Constant Propagation Algorithm for Explicitly Parallel Programs
In this paper, we present a constant propagation algorithm for explicitly parallel programs, which we call the Concurrent Sparse Conditional Constant propagation algorithm. This algorithm is an extension of the Sparse Conditional Constant propagation algorithm. Without considering the interaction between threads, classical optimizations lead to an incorrect program transformation for parallel programs. To make analyzing parallel programs possible, a new intermediate representation is needed. We introduce the Concurrent Static Single Assignment (CSSA) form to represent explicitly parallel programs with interleaving semantics and synchronization. The only parallel construct considered in this paper is cobegin/coend. A new confluence function, the π-assignment, which summarizes the information of interleaving statements between threads, is introduced. The Concurrent Control Flow Graph, which contains information about conflicting statements, control flow, and synchronization, is used as an underlying representation for the CSSA from.
12522566
Real Time Video Data Mining for Surveillance Video Streams
We extend our previous work [1] of the general framework for video data mining to further address the issue such as how to mine video data using motions in video streams. To extract and characterize these motions, we use an accumulation of quantized pixel differences among all frames in a video segment. As a result, the accumulated motions of segment are represented as a two dimensional matrix. Further, we develop how to capture the location of motions occurring in a segment using the same matrix generated for the calculation of the amount. We study how to cluster those segmented pieces using the features (the amount and the location of motions) we extract by the matrix above. We investigate an algorithm to find whether a segment has normal or abnormal events by clustering and modeling normal events, which occur mostly. In addition to deciding normal or abnormal, the algorithm computes Degree of Abnormality of a segment, which represents to what extent a segment is distant to the existing segments in relation with normal events. Our experimental studies indicate that the proposed techniques are promising.
17910425
TMO-structured distributed location information system prototype
To realize location-based services, it is essential to handle the extreme situation that must cope with a very large volume, at least millions, of moving items. In this paper, we describe a location information system prototype of GALIS, which is a cluster-based scalable distributed computing system architecture which consists of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone. The proposed system contains all of the major computing nodes of GALIS architecture and is developed as a middleware on top of commercial main-memory database engines and spatial database engines, for short-term data and long-term data processing, respectively. To show the usefulness of our system, some experimental results showing clear advantages of distributed computing are also explained.
5969110
An Efficient Encoding and Labeling for Dynamic XML Data
In order to efficiently determine structural relationships among XML elements and to avoid re-labeling for updates, much research about labeling schemes has been conducted, recently. However, a harmonic support of efficient query processing and updating has not been achieved. In this paper, we propose an efficient XML encoding and labeling scheme, called EXEL, which is a variant of the region numbering scheme using bit strings. In order to generate the ordinal and insert-friendly bit strings in EXEL, a novel binary encoding method is devised. Also, we devise a labeling scheme for a newly inserted node which incurs no re-labeling of pre-existing labels. These encoding and inserting methods are the bases of efficient query processing and the complete avoidance of re-labeling for updates. Moreover, EXEL supports all structural relationships in XPath and the relationships can be checked by SQL statements supported by an RDBMS. Finally, the experimental results show that EXEL provides fairly reasonable query processing performance while completely avoiding re-labeling for updates.
7800252
Imprecise data computation for high performance asynchronous processors
Instruction level parallelism(ILP) is strictly limited by various dependencies. In particular , data dependency is the major performance bottleneck of data intensive applications. To accelerate the execution of sequential code serialized due to data dependencies, this paper proposes an imprecise computation as a fast data computing technique for a high-performance asynchronous processor. To show the performance benefits of the suggested computing model, simulation results are presented. The imprecise computation can be used effectively in data intensive processing with a microprocessor, a Digital Signal Processor or a multimedia processor.