\maketitle
\section{Introduction}
+The use of multi-core architectures for solving large scientific problems seems to become imperative in a lot of cases.
+Whatever the scale of these architectures (distributed clusters, computational grids, embedded multi-core \ldots) they are generally
+well adapted to execute complexe parallel applications operating on a large amount of data. Unfortunately, users (industrials or scientists),
+who need such computational resources may not have an easy access to such efficient architectures. The cost of using the platform and/or the cost of
+testing and deploying an application are often very important. So, in this context it is difficult to optimize a given application for a given
+architecture. In this way and in order to reduce the access cost to these computing resources it seems very interesting to use a simulation environment.
+The advantages are numerous: development life cycle, code debugging, ability to obtain results quickly \ldots
+
+In this paper we focus on a class of highly efficient parallel algorithms called \emph{iterative algorithms}. The
+parallel scheme of iterative methods is quite simple. It generally involves the division of the problem
+into several \emph{blocks} that will be solved in parallel on multiple
+processing units. Then each processing unit has to
+compute an iteration, to send/receive some data dependencies to/from
+its neighbors and to iterate this process until the convergence of
+the method. Several well-known methods demonstrate the convergence of these algorithms~\cite{BT89,Bahi07}.
+In this processing mode a task cannot begin a new iteration while it
+has not received data dependencies from its neighbors. We say that the iteration computation follows a synchronous scheme.
+In the asynchronous scheme a task can compute a new iteration without having to
+wait for the data dependencies coming from its neighbors. Both
+communication and computations are asynchronous inducing that there is
+no more idle times, due to synchronizations, between two
+iterations~\cite{bcvc06:ij}. This model presents some advantages and drawbacks that we detail in section 2 but even if the number of iterations required to converge is
+generally greater than for the synchronous case, it appears that the asynchronous iterative scheme can significantly reduce overall execution
+times by suppressing idle times due to synchronizations~\cite{Bahi07} for more details.
+
+Nevertheless, in both cases (synchronous or asynchronous) it is very time consuming to find optimal configuration and deployment requirements
+for a given application on a given multi-core architecture. Finding good resource allocations policies under varying CPU power, network speeds and
+loads is very challenging and labor intensive.~\cite{Calheiros:2011:CTM:1951445.1951450}. This problematic is even more difficult for the asynchronous scheme
+where variations of the parameters of the execution platform can lead to very different number of iterations required to converge and so to very different execution times.
+In this challenging context we think that the use of a simulation tool can leverage the possibility of testing various platform scenarios.
+
+The main contribution of this paper is to show that the use of a simulation tool (i.e. the SimGrid toolkit~\cite{SimGrid}) in the context of real
+parallel applications (i.e. large linear system solver) can help developers to better tune their application for a given multi-core architecture.
+To show the validity of this approach we first compare the simulated execution of the multisplitting algorithm with the GMRES (Generalized Minimal Residual) solver
+\cite{ref1} both in synchronous mode. The obtained results on different simulated multi-core architectures confirm the results previously obtained on non simulated architecture.
+We also confirm the efficiency of the asynchronous multisplitting algorithm comparing to the synchronous GMRES. In this way and with a simple computing architecture (a laptop)
+SimGrid allows us (with small modifications of the MPI code) to run a test campaign of a real parallel iterative applications on different simulated multi-core architectures.
+To our knowledge, there is no related work on the large-scale multi-core simulation of a real synchronous and asynchronous iterative application.
+
+This paper is organized as follows:
+
\section{The asynchronous iteration model}
