X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/GMRES2stage.git/blobdiff_plain/96dcb243cd0224275446d6d85fab46ed72241a22..c1552aed123e4154c36983b72f5abd7c1578091f:/paper.tex diff --git a/paper.tex b/paper.tex index 9035059..a4c9b26 100644 --- a/paper.tex +++ b/paper.tex @@ -968,8 +968,7 @@ preconditioner in PETSc please consult~\cite{petsc-web-page}. Table~\ref{tab:03} shows the execution times and the number of iterations of example ex15 of PETSc on the Juqueen architecture. Different numbers of cores -are studied ranging from 2,048 up-to 16,383. Two preconditioners have been -tested: {\it mg} and {\it sor}. For those experiments, the number of components (or unknowns of the +are studied ranging from 2,048 up-to 16,383 with the two preconditioners {\it mg} and {\it sor}. For those experiments, the number of components (or unknowns of the problems) per core is fixed to 25,000, also called weak scaling. This number can seem relatively small. In fact, for some applications that need a lot of memory, the number of components per processor requires sometimes to be @@ -1036,7 +1035,21 @@ the number of iterations. So, the overall benefit of using TSIRM is interesting. \end{table*} -In Table~\ref{tab:04}, some experiments with example ex54 on the Curie architecture are reported. +In Table~\ref{tab:04}, some experiments with example ex54 on the Curie +architecture are reported. For this application, we fixed $\alpha=0.6$. As it +can be seen in that Table, the size of the problem has a strong influence on the +number of iterations to reach the convergence. That is why we have preferred to +change the threshold. If we set it to $1e-3$ as with the previous application, +only one iteration is necessray to reach the convergence. So Table~\ref{tab:04} +shows the results of differents executions with differents number of cores and +differents thresholds. As with the previous example, we can observe that TSIRM +is faster than FGMRES. The ratio greatly depends on the number of iterations for +FMGRES to reach the threshold. The greater the number of iterations to reach the +convergence is, the better the ratio between our algorithm and FMGRES is. This +experiment is also a weak scaling with approximately $25,000$ components per +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. \begin{table*}[htbp]