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<p class="MsoNormal">Good Morning,<o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-GB">I usually solve a non-symmetric discretization of the Poisson equation using GAMG+FGMRES.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">In the last days I tried to use BCGS in place of FGMRES, still using GAMG as preconditioner.<br>
No problem in finding the solution but I’m experiencing something I didn’t expect.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">The test case is a 25 millions cells domain with Dirichlet and Neumann boundary conditions.<br>
Both the solvers are able to solve the problem with an increasing number of MPI processes, but:<o:p></o:p></span></p>
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<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1"><span lang="EN-GB">FGMRES is about 25% faster than BCGS for all the processes number<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1"><span lang="EN-GB">Both solvers have the same scalability from 48 to 384 processes<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1"><span lang="EN-GB">Both solvers almost use the same amount of memory (FGMRES use a restart=30)<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span lang="EN-GB">Am I wrong expecting less memory consumption and more performance from BCGS with respect to FGMRES?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Thank you in advance for any help.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:IT">Marco Cisternino<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
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