A large number of real-life systems can be viewed as instances of the classical M/G/c/N queue. The exact analytical solution of this queueing model is not known, and a frequently-used approach is to replace the general service time distribution by a phase-type distribution. The advantage of this approach is that the resulting M/Ph/c/N queue can be described by familiar balance equations. The downside is that the size of the resulting state space suffers from the "dimensionality curse", i.e., exhibits combinatorial growth as the number of servers and/or phases increases. To circumvent this complexity issue, we propose to use, instead of .....
Generoso Pagano; Damien Dosimont; Guillaume Huard; Vania Marangozova-Martin; Jean-Marc Vincent
Détail
[Research Report], 2013, pp. 21. RR-8304
Début du résumé
The growing complexity of embedded system hardware and software makes their behavior analysis a challenging task. In this context, tracing appears to be a promising solution as it provides relevant information about the system execution. However, trace management and analysis are hindered by several issues like the diversity of trace formats, the incompatibility of trace analysis methods, the problem of trace size and its storage as well as by the lack of visualization scalability. In this paper we present FrameSoC, a new trace management infrastructure that solves all the above issues together. It provides generic solutions for trace storage and .....
François Cuvelier ; Caroline Japhet ; Gilles Scarella
Détail
[Research Report], 2013, pp. 40. RR-8305
Début du résumé
We describe different optimization techniques to perform the assembly of finite element matrices in Matlab and Octave, from the standard approach to recent vectorized ones, without any low level language used. We finally obtain a simple and efficient vectorized algorithm able to compete in performance with dedicated software such as FreeFEM++. The principle of this assembly algorithm is general, we present it for different matrices in the P1 finite elements case and in linear elasticity. We present numerical results which illustrate the computational costs of the different approaches .....
In this paper we present a new finite-difference method to simulate electropermeabilization models, like the model of Neu and Krassowska or the recent model of Kavian et al.. These models are based on the evolution of the electric potential in conducting media. The main feature lies in the transmission of the voltage potential which is proportional to the electric flux (the normal derivative of the potential). An adapted scheme is necessary to accurately simulate the voltage potential in the whole cell, notably at the membrane separating the cell from the outer medium. Our finite difference scheme is inspired by the .....
Paul Bedaride; Stéphane Genaud ; Augustin Degomme; Arnaud Legrand ; George Markomanolis; Martin Quinson; Mark Stillwell ; Frédéric Suter; Brice Videau
Détail
[Research Report], 2013, pp. 22. RR-8300
Début du résumé
Proper modeling of collective communications is essential for understanding the behavior of medium-to-large scale parallel applications, and even minor deviations in implementation can adversely affect the prediction of real-world performance. We propose a hybrid network model extending LogP based approaches to account for topology and contention in high-speed TCP networks. This model is validated within SMPI, an MPI implementation provided by the SimGrid simulation toolkit. With SMPI, standard MPI applications can be compiled and run in a simulated network environment, and traces can be captured without incurring errors from tracing overheads or poor clock synchronization as in physical experiments. SMPI .....
; Caroline Japhet 