VALUETOOLS 2008
INTER-PERF 2008WNS2 2008MODENETS 2008GAMECOMM 2008SMCTOOLS 2008

    VALUETOOLS

    3rd International ICST Conference on Performance Evaluation Methodologies and Tools

    Welcome to Athens! On behalf of the whole organizing team, we wholeheartedly welcome you to the third installment of Valuetools, Valuetools 2008. The first two installments took place in Pisa (2006) and Nantes (2007). So, again, the conference is taking place in a city of rich cultural heritage. We…

    Welcome to Athens! On behalf of the whole organizing team, we wholeheartedly welcome you to the third installment of Valuetools, Valuetools 2008. The first two installments took place in Pisa (2006) and Nantes (2007). So, again, the conference is taking place in a city of rich cultural heritage. We look forward to emulating the previous two installments also in terms of their scientific success. The motivation behind Valuetools is the observation that an impressive range of methodologies and tools have been developed recently for the purpose of performance evaluation, across many disparate research fields. Valuetools is meant to be a forum that will allow researchers to compare and debate the full range of these tools and methodologies, and in addition promote the interdisciplinary flow of technical information.

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    Editor(s): John Baras and Costas Courcoubetis
    Publisher
    ICST
    ISBN
    978-963-9799-31-8
    Conference dates
    20th–24th Oct 2008
    Location
    Athens, Greece
    Appeared in EUDL
    29th Nov 2011
    Appears in
    ACM Digital Library

    Copyright © 2011–2013 ICST

    • Oja's algorithm for graph clustering and Markov spectral decomposition

      Research Article in 3rd International ICST Conference on Performance Evaluation Methodologies and Tools

      V. Borkar, S.P. Meyn

      Abstract
      Given a positive definite matrix M and an integer Nm ≥ 1, Oja's subspace algorithm will provide convergent estimates of the first Nm eigenvalues of M along with the corresponding eigenvectors. It is …Given a positive definite matrix M and an integer Nm ≥ 1, Oja's subspace algorithm will provide convergent estimates of the first Nm eigenvalues of M along with the corresponding eigenvectors. It is a common approach to principal component analysis. This paper introduces a normalized stochastic-approximation implementation of Oja's subspace algorithm, as well as new applications to the spectral decomposition of a reversible Markov chain. Stability and convergence are established under conditions far milder than assumed in previous work. Applications to graph clustering and Markov spectral decomposition are surveyed, along with numerical results.
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    • Fair resource allocation in wireless networks in the presence of a jammer

      Research Article in 3rd International ICST Conference on Performance Evaluation Methodologies and Tools

      Eitan Altman, Konstantin Avrachenkov, Andrey Garnaev

      Abstract
      We consider jamming in wireless networks in the framework of zero-sum games with α-utility functions. The base station has to distribute the power fairly among the users in the presence of a jammer. …We consider jamming in wireless networks in the framework of zero-sum games with α-utility functions. The base station has to distribute the power fairly among the users in the presence of a jammer. The jammer in turn tries to distribute its power among the channels to produce as much harm as possible. The Shannon capacity and SNIR optimization are particular cases of the proposed more general α-fairness SNIR based utility functions. Specifically, we consider two α-fairness utility functions, based on SNIR and Shifted SNIR. This game can also be viewed as a minimax problem against the nature. We show that the game has the unique equilibrium and investigate its properties. In particular, in several important cases we present the equilibrium strategies and the Jain's fairness index in closed form. It turns out that there is an important difference between SNIR and Shifted SNIR α-fairness utility functions. In the case of the SNIR based utility function all users obtain nonzero powers when α > 0. On contrary, when the Shifted SNIR based utility function is used, some users with bad channel conditions might not receive any power at all. We have also detected a surprising non-monotone behaviour of the Jain's fairness index in the case of the SNIR based utility function.
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    • Distributed resource allocation algorithms for peer-to-peer networks

      Research Article in 3rd International ICST Conference on Performance Evaluation Methodologies and Tools

      Iordanis Koutsopoulos, George Iosifidis

      Abstract
      In peer-to-peer networks, each peer plays the role of client and server. As server, it receives content requests made by other peers and needs to decide on what basis and to what extent it will satis…In peer-to-peer networks, each peer plays the role of client and server. As server, it receives content requests made by other peers and needs to decide on what basis and to what extent it will satisfy these requests by uploading content to others. As client, it addresses its own requests to appropriate peers to download desired content after resources are granted. We consider a network of peers in a star topology, where the bottleneck is the capacity of the access link connecting a peer to the backbone. Different peers have different utility functions which are private information and capture a peer's selfishness or desire for content. The objective is to maximize the sum of utilities of peers. We intend to answer the following questions in a peer-to-peer network: what portions of its link capacity does each peer allocate to upload flows from other peers and download flows for itself? How does a peer decide which portion of bandwidth will be allocated to each upload flow and download flow? How can these decisions be taken in a decentralized autonomous fashion? Although each peer directly obtains utility only from downloads, in the presence of an incentive protocol it would like to allow just enough capacity for uploads of others so that it is not punished by the protocol. The global link sharing problem of maximizing total utility is hard to solve in a distributed fashion because of coupled utility functions and constraints. That is, the utility of each peer depends on allocation decisions of others. By defining auxiliary variables and constraints, we transform the problem into one that is amenable to "distributization" by dual decomposition. The iterative algorithm involves solving separate optimization problems by each peer and updating Lagrange multipliers. Interestingly, the Lagrange multipliers corresponding to the newly added constraints are interpreted as reciprocals of pairwise reputation metrics. This leads us to a meaningful reputation-driven protocol with the desirable property that only the amounts of requested and granted bandwidth are circulated, and not reputations. The protocol is lightweight in terms of computational complexity and overhead and converges to the globally optimal allocation.
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    • Response time distribution of flash memory accesses

      Research Article in 3rd International ICST Conference on Performance Evaluation Methodologies and Tools

      Peter G. Harrison, Naresh M. Patel, Soraya Zertal

      Abstract
      Flash memory is becoming an increasingly important storage component among non-volatile storage devices. Its cost is decreasing dramatically, which makes it a serious competitor of disks and a candid…Flash memory is becoming an increasingly important storage component among non-volatile storage devices. Its cost is decreasing dramatically, which makes it a serious competitor of disks and a candidate for being the storage device of the future. Consequently, there is an urgent need for models and tools to analyse its behaviour and evaluate its effects on a system's performance. We propose a fluid model with priority to investigate the response time characteristics of Flash memory accesses. This model can represent well the Flash access operations, respecting the erase/write/read relative priorities.
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    • Performance of SCTP in Wi-Fi and WiMAX networks with multi-homed mobiles

      Research Article in 3rd International ICST Conference on Performance Evaluation Methodologies and Tools

      Vicuña Nelson, Jiménez Tania, Hayel Yezekael

      Abstract
      This paper provides an exhaustive performance analysis by simulation of the SCTP transfer protocol in WiMAX and Wi-Fi networks. We provide also a comparison of SCTP with both transfer protocols UDP f…This paper provides an exhaustive performance analysis by simulation of the SCTP transfer protocol in WiMAX and Wi-Fi networks. We provide also a comparison of SCTP with both transfer protocols UDP for "VoIP-like" applications and TCP for FTP sessions, as SCTP can support these two types (elastic and non-elastic) of traffic. Finally, we study how SCTP performs when a mobile is multi-homed, i.e. connected simultaneously to two wireless networks (Wi-Fi and WiMAX).
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