Scalable desktop grid system

Desktop grids are easy to install on large number of personal computers, which is a prerequisite for the spread of grid technology. Current desktop grids connect all PCs into a flat hierarchy, that is, all computers to a central server. SZTAKI Desktop Grid starts from a standalone desktop grid, as a building block. It is extended to include clusters displaying as single powerful PCs, while using their local resource management system. Such building blocks support overtaking additional tasks from other desktop grids, enabling the set-up of a hierarchy. Desktop grids with different owners thus can share resources, although only in a hierarchical structure. This brings desktop grids closer to other grid technologies where sharing resources by several users is the most important feature

Schlafender Riese Kongo-Fluss: Wassernutzung zwischen regionaler Integration und sektoralen Zielkonflikten

Der Ausbau der Wassernutzung am Kongo könnte der Region einen Entwicklungsschub verschaffen, droht aber mit der Begünstigung partikulärer Nutzungsinteressen einherzugehen. In seinem weitläufigen Einzugsgebiet ist der Fluss das wichtigste Verkehrsnetz und die Lebensader des afrikanischen Regenwalds, der wiederum die Existenzgrundlage von Millionen Menschen sichert. Die Wasser- und Nahrungsmittelversorgung der Region ließe sich mit seinen Ressourcen deutlich verbessern, die Hydroenergiepotentiale könnten den Strombedarf des gesamten Kontinents decken. Der geplante Bau weiterer Großdämme an den Inga-Fällen zeigt, dass die zehn Anrainerstaaten gemeinsame Ziele verfolgen, aber auch, dass sich Konflikte zwischen einzelnen Sektoren verschärfen. Die inkonsistente Haltung Deutschlands in heiklen Grundsatzfragen der Entwicklungszusammenarbeit und Wasseraußenpolitik erschwert es, diese Prozesse konstruktiv zu begleiten. (Autorenreferat

SZTAKI desktop grid: a modular and scalable way of building large computing grids

So far BOINC based desktop grid systems have been applied at the global computing level. This paper describes an extended version of BOINC called SZTAKI desktop grid (SZDG) that aims at using desktop grids (DGs) at local (enterprise/institution) level. The novelty of SZDG is that it enables the hierarchical organisation of local DGs, i.e., clients of a DG can be DGs at a lower level that can take work units from their higher level DG server. More than that, even clusters can be connected at the client level and hence work units can contain complete MPI programs to be run on the client clusters. In order to easily create master/worker type DG applications a new API, called as the DC-API has been developed. SZDG and DC-API has been successfully applied both at the global and local level, both in academic institutions and in companies to solve problems requiring large computing power

Improving I/O Performance for Exascale Applications through Online Data Layout Reorganization

The applications being developed within the U.S. Exascale Computing Project (ECP) to run on imminent Exascale computers will generate scientific results with unprecedented fidelity and record turn-around time. Many of these codes are based on particle-mesh methods and use advanced algorithms, especially dynamic load-balancing and mesh-refinement, to achieve high performance on Exascale machines. Yet, as such algorithms improve parallel application efficiency, they raise new challenges for I/O logic due to their irregular and dynamic data distributions. Thus, while the enormous data rates of Exascale simulations already challenge existing file system write strategies, the need for efficient read and processing of generated data introduces additional constraints on the data layout strategies that can be used when writing data to secondary storage. We review these I/O challenges and introduce two online data layout reorganization approaches for achieving good tradeoffs between read and write performance. We demonstrate the benefits of using these two approaches for the ECP particle-in-cell simulation WarpX, which serves as a motif for a large class of important Exascale applications. We show that by understanding application I/O patterns and carefully designing data layouts we can increase read performance by more than 80 percent

Toward a first-principles integrated simulation of tokamak edge plasmas

Performance of the ITER is anticipated to be highly sensitive to the edge plasma condition. The edge pedestal in ITER needs to be predicted from an integrated simulation of the necessary first-principles, multi-scale physics codes. The mission of the SciDAC Fusion Simulation Project (FSP) Prototype Center for Plasma Edge Simulation (CPES) is to deliver such a code integration framework by (1) building new kinetic codes XGC0 and XGC1, which can simulate the edge pedestal buildup; (2) using and improving the existing MHD codes ELITE, M3D-OMP, M3D-MPP and NIMROD, for study of large-scale edge instabilities called Edge Localized Modes (ELMs); and (3) integrating the codes into a framework using cutting-edge computer science technology. Collaborative effort among physics, computer science, and applied mathematics within CPES has created the first working version of the End-to-end Framework for Fusion Integrated Simulation (EFFIS), which can be used to study the pedestal-ELM cycles

Dataflow Parallel Database Systems

Machine, 3DPAM) working in a distributed environment are based on the dataflow principle (more exactly on the logicflow one which is an extension of the dataflow principle). The system executes Prolog queries on sets of rules and facts fully exploiting the available OR and pipeline AND parallelism of the Prolog programs. The inherently sequential subtasks are executed by conventional Warren Abstract Machines (WAM). The system is described in [Kacs92] and [Neme94]. The description of WAM can be found in [Warr83]. With the extension of LOGFLOW a KBMS can be created or a new parallel relational DBMS can be implemented based on the engine of the system. In this paper we examine the latter possibility. The KBMSs and Prolog based expert systems should be carefully studied before implementing a new one based on LOGFLOW. 11.2 Transputers A multi-transputer machine is a distributed system. The processors (having their own memories) are connected together via binary links. The small number of ..