X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/GMRES2stage.git/blobdiff_plain/c1552aed123e4154c36983b72f5abd7c1578091f..81dc474c4a3dc51b326e64f816210ad947fc75f0:/paper.tex diff --git a/paper.tex b/paper.tex index a4c9b26..2583813 100644 --- a/paper.tex +++ b/paper.tex @@ -1051,6 +1051,24 @@ core. It can also be observed that the difference between CGLS and LSQR is not significant. Both can be good but it seems not possible to know in advance which one will be the best. +Table~\ref{tab:05} show a strong scaling experiment with the exemple ex54 on the +Curie architecture. So in this case, the number of unknownws is fixed to +$204,919,225$ and the number of cores ranges from $512$ to $8192$ with the power +of two. The threshold is fixed to $5e-5$ and only the $mg$ preconditioner has +been tested. Here again we can see that TSIRM is faster that FGMRES. Efficiecy +of each algorithms is reported. It can be noticed that FGMRES is more efficient +than TSIRM except with $8,192$ cores and that its efficiency is greater that one +whereas the efficiency of TSIRM is lower than one. Nevertheless, the ratio of +TSIRM with any version of the least-squares method is always faster. With +$8,192$ cores when the number of iterations is far more important for FGMRES, we +can see that it is only slightly more important for TSIRM. + +In Figure~\ref{fig:02} we report the number of iterations per second for +experiments reported in Table~\ref{tab:05}. This Figure highlights that the +number of iterations per seconds is more of less the same for FGMRES and TSIRM +with a little advantage for FGMRES. It can be explained by the fact that, as we +have previously explained, that the iterations of the least-sqaure steps are not +taken into account with TSIRM. \begin{table*}[htbp] \begin{center} @@ -1081,6 +1099,12 @@ one will be the best. \label{fig:02} \end{figure} + +Concerning the experiments some other remarks are interesting. We can tested +other examples of PETSc (ex29, ex45, ex49). For all these examples, we also +obtained similar gain between GMRES and TSIRM but those examples are not +scalable with many cores. In general, we had some problems with more than +$4,096$ cores. %%%********************************************************* %%%********************************************************* @@ -1103,13 +1127,14 @@ experiments up to 16,394 cores have been led to verify that TSIRM runs 5 or 7 times faster than GMRES. -For future work, the authors' intention is to investigate -other kinds of matrices, problems, and inner solvers. The -influence of all parameters must be tested too, while -other methods to minimize the residuals must be regarded. -The number of outer iterations to minimize should become -adaptative to improve the overall performances of the proposal. -Finally, this solver will be implemented inside PETSc. +For future work, the authors' intention is to investigate other kinds of +matrices, problems, and inner solvers. The influence of all parameters must be +tested too, while other methods to minimize the residuals must be regarded. The +number of outer iterations to minimize should become adaptative to improve the +overall performances of the proposal. Finally, this solver will be implemented +inside PETSc. This would be very interesting because it would allow us to test +all the non-linear examples and compare our algorithm with the other algorithm +implemented in PETSc. % conference papers do not normally have an appendix