4,402 research outputs found
Power Saving Experiments for Large Scale Global Optimization
Green computing, an emerging field of research that seeks to reduce excess power consumption in high performance computing (HPC), is gaining popularity among researchers. Research in this field often relies on simulation or only uses a small cluster, typically 8 or 16 nodes, because of the lack of hardware support. In contrast, System G at Virginia Tech is a 2592 processor supercomputer equipped with power aware components suitable for large scale green computing research. DIRECT is a deterministic global optimization algorithm, implemented in the mathematical software package VTDIRECT95. This paper explores the potential energy savings for the parallel implementation of DIRECT, called pVTdirect, when used with a large scale computational biology application, parameter estimation for a budding yeast cell cycle model, on System G. Two power aware approaches for pVTdirect are developed and compared against the CPUSPEED power saving system tool. The results show that knowledge of the parallel workload of the underlying application is beneficial for power management
A multiobjective optimization approach to statistical mechanics
Optimization problems have been the subject of statistical physics
approximations. A specially relevant and general scenario is provided by
optimization methods considering tradeoffs between cost and efficiency, where
optimal solutions involve a compromise between both. The theory of Pareto (or
multi objective) optimization provides a general framework to explore these
problems and find the space of possible solutions compatible with the
underlying tradeoffs, known as the {\em Pareto front}. Conflicts between
constraints can lead to complex landscapes of Pareto optimal solutions with
interesting implications in economy, engineering, or evolutionary biology.
Despite their disparate nature, here we show how the structure of the Pareto
front uncovers profound universal features that can be understood in the
context of thermodynamics. In particular, our study reveals that different
fronts are connected to different classes of phase transitions, which we can
define robustly, along with critical points and thermodynamic potentials. These
equivalences are illustrated with classic thermodynamic examples.Comment: 14 pages, 8 figure
Design and Implementation of a Massively Parallel Version of DIRECT
This paper describes several massively parallel implementations for a global search algorithm DIRECT.
Two parallel schemes take different approaches to address DIRECT's design challenges imposed by memory requirements
and data dependency. Three design aspects in topology, data structures, and task allocation are compared in
detail. The goal is to analytically investigate the strengths and weaknesses of these parallel schemes, identify several
key sources of inefficiency, and experimentally evaluate a number of improvements in the latest parallel DIRECT
implementation. The performance studies demonstrate improved data structure efficiency and load balancing on a
2200 processor cluster
Convex Hulls, Triangulations, and Voronoi Diagrams of Planar Point Sets on the Congested Clique
We consider geometric problems on planar -point sets in the congested
clique model. Initially, each node in the -clique network holds a batch of
distinct points in the Euclidean plane given by -bit
coordinates. In each round, each node can send a distinct -bit
message to each other node in the clique and perform unlimited local
computations. We show that the convex hull of the input -point set can be
constructed in rounds, where is the size of the
hull, on the congested clique. We also show that a triangulation of the input
-point set can be constructed in rounds on the congested
clique. Finally, we demonstrate that the Voronoi diagram of points with
-bit coordinates drawn uniformly at random from a unit square can be
computed within the square with high probability in rounds on the
congested clique.Comment: 17 pages, 7 figure
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