17,310 research outputs found
Enhanced Cluster Computing Performance Through Proportional Fairness
The performance of cluster computing depends on how concurrent jobs share
multiple data center resource types like CPU, RAM and disk storage. Recent
research has discussed efficiency and fairness requirements and identified a
number of desirable scheduling objectives including so-called dominant resource
fairness (DRF). We argue here that proportional fairness (PF), long recognized
as a desirable objective in sharing network bandwidth between ongoing flows, is
preferable to DRF. The superiority of PF is manifest under the realistic
modelling assumption that the population of jobs in progress is a stochastic
process. In random traffic the strategy-proof property of DRF proves
unimportant while PF is shown by analysis and simulation to offer a
significantly better efficiency-fairness tradeoff.Comment: Submitted to Performance 201
Cluster Computing and the Power of Edge Recognition
We study the robustness--the invariance under definition changes--of the
cluster class CL#P [HHKW05]. This class contains each #P function that is
computed by a balanced Turing machine whose accepting paths always form a
cluster with respect to some length-respecting total order with efficient
adjacency checks. The definition of CL#P is heavily influenced by the defining
paper's focus on (global) orders. In contrast, we define a cluster class,
CLU#P, to capture what seems to us a more natural model of cluster computing.
We prove that the naturalness is costless: CL#P = CLU#P. Then we exploit the
more natural, flexible features of CLU#P to prove new robustness results for
CL#P and to expand what is known about the closure properties of CL#P.
The complexity of recognizing edges--of an ordered collection of computation
paths or of a cluster of accepting computation paths--is central to this study.
Most particularly, our proofs exploit the power of unique discovery of
edges--the ability of nondeterministic functions to, in certain settings,
discover on exactly one (in some cases, on at most one) computation path a
critical piece of information regarding edges of orderings or clusters
Separation kernel robustness testing : the xtratum case study
With time and space partitioned architectures becoming increasingly appealing to the European space sector, the dependability of separation kernel technology is a key factor to its applicability in European Space Agency projects. This paper explores the potential of the data type fault model, which injects faults through the Application Program Interface, in separation kernel robustness testing. This fault injection methodology has been tailored to investigate its relevance in uncovering vulnerabilities within separation kernels and potentially contributing towards fault removal campaigns within this domain. This is demonstrated through a robustness testing case study of the XtratuM separation kernel for SPARC LEON3 processors. The robustness campaign exposed a number of vulnerabilities in XtratuM, exhibiting the potential benefits of using such a methodology for the robustness assessment of separation kernels.peer-reviewe
Self-organising management of Grid environments
This paper presents basic concepts, architectural principles and algorithms for efficient resource and security management in cluster computing environments and the Grid. The work presented in this paper is funded by BTExacT and the EPSRC project SO-GRM (GR/S21939)
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