A cost-effective heuristic to schedule local and remote memory in cluster computers

Cluster computers represent a cost-effective alternative solution to supercomputers. In these systems, it is common to constrain the memory address space of a given processor to the local motherboard. Constraining the system in this way is much cheaper than using a full-fledged shared memory implementation among motherboards. However, memory usage among motherboards can be unfairly balanced. On the other hand, remote memory access (RMA) hardware provides fast interconnects among the motherboards of a cluster. RMA devices can be used to access remote RAM memory from a local motherboard. This work focuses on this capability in order to achieve a better global use of the total RAM memory in the system. More precisely, the address space of local applications is extended to remote motherboards and is used to access remote RAM memory. This paper presents an ideal memory scheduling algorithm and proposes a cost-effective heuristic to allocate local and remote memory among local applications. Compared to the devised ideal algorithm, the heuristic obtains the same (or closely resembling) results while largely reducing the computational cost. In addition, we analyze the impact on the performance of stand alone applications varying the memory distribution among regions (local, local to board, and remote). Then, this study is extended to any number of concurrent applications. Experimental results show that a QoS parameter is needed in order to avoid unacceptable performance degradation. © 2011 Springer Science+Business Media, LLC.This work was supported by Spanish CICYT under Grant TIN2009-14475-C04-01 and by Consolider-Ingenio under Grant CSD2006-00046.Serrano Gómez, M.; Sahuquillo Borrás, J.; Petit Martí, SV.; Hassan Mohamed, H.; Duato Marín, JF. (2012). A cost-effective heuristic to schedule local and remote memory in cluster computers. 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Juniper Invasions in Grasslands: Research Needs and Intervention Strategies

On the Ground Despite prescribed fire programs, invasive juniper trees are increasing in the Great Plains. Continued encroachment of junipers in the Great Plains, especially eastern redcedar and Ashe's juniper, is degrading grasslands and increasing health concerns through pollen production. Biological and ecological research needs include effects on soil and water as well as restoration potential after a mature invasion is treated. The interface of social science, ecology, economics, and policy may yield productive approaches to slowing the invasion. © 2017The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

Design and Implementation of a One-Sided Communication Interface for the IBM eServer Blue Gene R ○ Supercomputer

This paper discusses the design and implementation of a onesided communication interface for the IBM Blue Gene/L supercomputer. This interface facilitates ARMCI and the Global Arrays toolkit and can be used by other one-sided communication libraries. New protocols, interrupt driven communication, and compute node kernel enhancements were required to enable these libraries. Three possible methods for enabling ARMCI on the Blue Gene/L software stack are discussed. A detailed look into the development process shows how the implementation of the one-sided communication interface was completed. This was accomplished on a compressed time scale with the collaboration of various organizations within IBM and open source communities. In addition to enabling the one-sided libraries, bandwidth enhancements were made for communication along a diagonal on the Blue Gene/L torus network. The maximum bandwidth improved by a factor of three. This work will enable a variety of one-sided applications to run on Blue Gene/L