+In the scope of this paper, we have chosen the SimGrid
+toolkit~\cite{SimGrid,casanova+giersch+legrand+al.2014.versatile}
+to simulate the behavior of parallel iterative linear solvers on different
+computational grid configurations. In opposite to most of the simulators which
+are stayed very oriented-application, the SimGrid framework is designed to study
+the behavior of many large-scale distributed computing platforms as Grids,
+Peer-to-Peer systems, Clouds or High Performance Computation systems. It is
+still actively developed by the scientific community and distributed as an open
+source software.
+
+SimGrid provides four user interfaces which can be convenient for different
+distributed applications~\cite{casanova+legrand+quinson.2008.simgrid}. In this
+paper we are interested on the SMPI user interface (Simulator MPI) which
+implements about \np[\%]{80} of the MPI 2.0 standard and allows minor
+modifications of the initial code~\cite{bedaride+degomme+genaud+al.2013.toward}
+(see Section~\ref{sec:04.02}). SMPI enables the direct simulation of the
+execution, as in the real life, of an unmodified MPI distributed application,
+and gets accurate results with the detailed resources consumption.
+
+SimGrid simulator uses at least three XML input files describing the
+computational grid resources: the number of clusters in the grid, the number of
+processors/cores in each cluster, the detailed description of the intra and
+inter networks and the list of the hosts in each cluster (see the details in
+Section~\ref{sec:expe}). SimGrid uses a fluid model to simulate the program
+execution. It allows several simulation modes which produce accurate
+results~\cite{bedaride+degomme+genaud+al.2013.toward,velho+schnorr+casanova+al.2013.validity}. For
+instance, the "in vivo" mode really executes the computation but "intercepts"
+the communications (the execution time is then evaluated according to the
+parameters of the simulated platform). It is also possible for SimGrid/SMPI to
+only keep the duration of large computations by skipping them. Moreover the
+application can be run "in vitro" mode by sharing some in-memory structures
+between the simulated processes and thus allowing the use of very large-scale
+data.
+
+The choice of SimGrid/SMPI as a simulator tool in this study has been emphasized
+by the results obtained by several studies to validate, in the real
+environments, the behavior of different network models simulated in
+SimGrid~\cite{velho+schnorr+casanova+al.2013.validity}. Other studies underline
+the comparison between the real MPI application executions and the SimGrid/SMPI
+ones~\cite{guermouche+renard.2010.first,clauss+stillwell+genaud+al.2011.single,bedaride+degomme+genaud+al.2013.toward}. These
+works show the accuracy of SimGrid simulations compared to the executions on
+real physical architectures.