X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/Krylov_multi.git/blobdiff_plain/c9242f9fee68ee32282c6b18679048eb4c3056b4..94fdd01d0a73ca3bb8fd2c3afe8a49af5774595a:/krylov_multi_reviewed.tex?ds=sidebyside diff --git a/krylov_multi_reviewed.tex b/krylov_multi_reviewed.tex index 73881ba..4cad7d7 100644 --- a/krylov_multi_reviewed.tex +++ b/krylov_multi_reviewed.tex @@ -8,7 +8,8 @@ \usepackage{multirow} \usepackage{authblk} -\algnewcommand\algorithmicinput{\textbf{Input:}} + +\algnewcommand\algorithmicinput{\textbf{I1nput:}} \algnewcommand\Input{\item[\algorithmicinput]} \algnewcommand\algorithmicoutput{\textbf{Output:}} @@ -394,6 +395,9 @@ $743^3$ & 8,192 (4x2,048) & 704.4 & 87,822 & 4.80e-07 & 110.3 & \end{table} + + + From these experiments, it can be observed that the multisplitting version is always faster than the GMRES version. The acceleration gain of the multisplitting version ranges between 4 and 6. It can be noticed that the number of @@ -403,6 +407,40 @@ better performance than simply using 2 clusters. In fact, we can notice that the precision with 2 clusters is slightly better but in both cases the precision is under the specified threshold. + +%%% AJOUTE************************ +%%%******************************* +In Figure~\ref{fig:01}, the number of iterations per second is reported for both +GMRES and the multisplitting methods. It should be noted that we took only the +inner number of iterations (i.e. the GMRES iterations) for the multisplitting +method. Iterations of CGNR are not taken into account. From this figure, it can +be seen that the number of iterations per second is higher with GMRES but it is +not so different with the multisplitting method. For the case with $8,192$ +cores, the number of iterations per second with 4 clusters is approximately +equals to 115. So it is not different from GMRES. + + +\begin{figure}[htbp] +\centering + \includegraphics[width=0.7\textwidth]{nb_iter_sec} +\caption{Number of iterations per second with the same parameters as in Table~\ref{tab1} (weak scaling) with only 2 clusters} +\label{fig:01} +\end{figure} + + +\noindent {\bf Final remarks:}\\ +It should be noted, on the one hand, that the development of a complete new +method usable with any kind of problem is a really long and fastidious task if +one is working from scratch. On the other hand, using an existing tool for the +inner solver is also not easy because it requires to make link between the inner +solver and the outer one. We plan to do that later with engineers working +specifically on that point. Moreover, we think that it is very important to +analyze the convergence of this method compared to other method. In this work, +we have focused on the description of this method and its performance with a +typical application. Many other investigations are required for this method as explained in the next section. +%%%******************************* +%%%******************************* + \section{Conclusion and perspectives} We have implemented a Krylov multisplitting method to solve sparse linear systems on large-scale computing platforms. We have developed a synchronous