5614305
Performance evaluation of a firewall-compliant Globus-based wide-area cluster system
Presents a performance evaluation of a wide-area cluster system based on a firewall-enabled Globus metacomputing toolkit. In order to establish communication links beyond the firewall, we have designed and implemented a resource manager called RMF (Resource Manager beyond the Firewall) and the Nexus Proxy, which relays TCP communication links beyond the firewall. In order to extend the Globus metacomputing toolkit to become firewall-enabled, we have built the Nexus Proxy into the Globus toolkit. We have built a firewall-enabled Globus-based wide-area cluster system in Japan and run some benchmarks on it. In this paper, we report various performance results, such as the communication bandwidth and latencies obtained, as well as application performance involving a tree search problem. In a wide-area environment, the communication latency through the Nexus Proxy is approximately six times larger when compared to that of direct communications. As the message size increases, however, the communication overhead caused by the Nexus Proxy can be negligible. We have developed a tree search problem using MPICH-G. We used a self-scheduling algorithm, which is considered to be suitable for a distributed heterogeneous metacomputing environment since it performs dynamic load balancing with low overhead. The performance results indicate that the communication overhead caused by the Nexus Proxy is not a severe problem in metacomputing environments.
16039028
Overlay Weaver: An overlay construction toolkit
A layered model of structured overlays has been proposed and it enabled development of a routing layer independently of higher-level services such as DHT and multicast. The routing layer has to include other part than a routing algorithm, which is essential for routing. It is routing process, which is common to various routing algorithms and can be decoupled from a routing algorithm. We demonstrated the decomposition by implementing an overlay construction toolkit Overlay Weaver. It facilitates implementation of routing algorithms and we could multiple well-known algorithms just in hundreds of lines of code with the toolkit. The decomposition also enables multiple implementations of the common routing process. Two implementations the toolkit provides perform iterative and recursive routing, respectively. Additionally, to our knowledge, the toolkit is the first feasibility proof of the layered model by supporting multiple algorithms and the higher-level services. Such modular design contributes to our goal, which is facilitation of rapid development of realistic routing algorithms and their application. We demonstrates that Overlay Weaver supports the goal by conducting large-scale tests and comparisons of algorithms on a single computer. The resulting algorithm implementations work on a real TCP/IP network as it is.
2787964
Implementation of Fault-Tolerant GridRPC Applications
A task parallel application is implemented with Ninf-G, a GridRPC system. A series of experiments are conducted on the Grid testbed in Asia Pacific for three months. Through tens of long executions, typical fault patterns were collected, and instability of the network throughput was determined to be a major reason of the faults. Several important points are stressed to avoid task throughput decline due to the fault-recovery operations: Timeout minimization for fault detection, background recovery, redundant task assignments, and so on. This study also issues a steer for design of the automated fault-tolerant mechanism in an upper layer of the GridRPC framework.
13964619
Parallelization of Saprse Cholesky Factorization on an SMP Cluster
In this paper, we present parallel implementations of the sparse Cholesky factorization kernel in the SPLASH-2 programs to evaluate performance of a Pentium Pro based SMP cluster. Solaris threads and remote memory operations are utilized for intranode parallelism and internode communications, respectively. Sparse Cholesky factorization is a typical irregular application with a high communication to computation ratio and no global synchronization between steps. We efficiently parallelized using asynchronous message handling instead of lock-based mutual exclusion between nodes, because synchronization between nodes reduces the performance significantly. We also found that the mapping of processes to processors on an SMP cluster affects the performance especially when the communication latency can not be hidden.
5670471
Design, implementation and performance evaluation of GridRPC programming middleware for a large-scale computational grid
This paper reports on the design, implementation and performance evaluation of a suite of GridRPC programming middleware called Ninf-G Version 2 (Ninf-G2). Ninf-G2 is a reference implementation of the GridRPC API, a proposed GGF standard. Ninf-G2 has been designed so that it provides 1) high performance in a large-scale computational Grid, 2) the rich functionalities which are required to adapt to compensate for the heterogeneity and unreliability of a Grid environment, and 3) an API which supports easy development and execution of Grid applications. Ninf-G2 is implemented to work with basic Grid services, such as GSI, GRAM, and MDS in the Globus Toolkit version 2. The performance ofNinf-G2 was evaluated using a weather forecasting system which was developed using Ninf-G2. The experimental results indicate that high performance can be attained even in relatively fine-grained task-parallel applications on hundreds of processors in a Grid environment.
15968684
GEO Grid: Grid Infrastructure for Integration of Huge Satellite Imagery and Geoscience Data Setsets
We have designed Global Earth Observation(GEO) Grid, which is an infrastructure for archiving and processing huge satellite imagery and GIS geographical data sets. Users can immediately access the full archive and process the desired data areas on demand using the latest calibration and analysis algorithms through standardized web services interfaces on basic OGSA services. GEO Grid is based on four layers, hardware, virtual storage, application and data services, and user interface. Each layer has the potential for extendability. We constructed GEO Grid to process satellite data taken by ASTER launched at the end of 1999 as an EOS project.
30858440
Vision based navigation system for autonomous mobile robot with global matching
We have previously developed a navigation system for an autonomous mobile robot. It can find the landmarks on the ceiling for navigation. However, when the robot fails to recognize a landmark, the robot can not calculate the self-position. So, the robot has to prepare for the behavior of error recovery. But an error that is not able to recover may occur. In such a case, the robot needs to relocate the self-position. In this paper, we define global matching as the behavior that is able to relocate the self-position and propose to use this module for the error recovery in HALAS (hierarchical adaptive and learning architecture system) that we have proposed as a hierarchical system.
42879781
Vision based navigation system by variable template matching for autonomous mobile robot
We have previously developed a navigation system for autonomous mobile robots. It can find landmarks on the ceiling to move and work. However, it is impossible to recognize landmarks when the size of landmark is different from the size of template. In such cases, the robot cannot continue to work. Therefore we proposed variable template matching (VTM) that makes it possible to recognize landmarks of different sizes. We realize VTM by using the optimization method called the evolution strategy (ES). The robot can recognize the landmark faster, inferring landmark parameters by binary density projection.
27048178
Mechanism and control of mobile pipeline maintenance robot with lazy tongs mechanism
A new type of mobile pipeline maintenance robot has been designed to clarify the feasibility of lazy tongs mechanism for adaptation to various size pipelines. The robot basically consists of three modules with two joints between modules and can move straight and spirally along the surface of pipeline. The robot can change its arm length in order to move on the pipeline of various size from 25 A to 100 A, and pass over obstacles such as reducer, diffuser, flange and other plant equipment. The control of the robot is so complicated that the modified dual control mode is introduced using the coordinate transformation matrix. By calculating the position and attitude of the robot under the control mode, the manoeuvrability of passing over a reducer is shown with experimental results.