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Mark,</div>
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The application code reads in parameters from an input file, where we can put the PETSc runtime options. Then we pass the options to PetscInitialize(...). Does that sounds right?</div>
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Cho<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Ng, Cho-Kuen <cho@slac.stanford.edu><br>
<b>Sent:</b> Thursday, June 29, 2023 8:32 PM<br>
<b>To:</b> Mark Adams <mfadams@lbl.gov><br>
<b>Cc:</b> petsc-users@mcs.anl.gov <petsc-users@mcs.anl.gov><br>
<b>Subject:</b> Re: [petsc-users] Using PETSc GPU backend</font>
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Mark,</div>
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Thanks for the information. How do I put the runtime options for the executable, say, a.out, which does not have the provision to append arguments? Do I need to change the C++ main to read in the options?</div>
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Cho<br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Mark Adams <mfadams@lbl.gov><br>
<b>Sent:</b> Thursday, June 29, 2023 5:55 PM<br>
<b>To:</b> Ng, Cho-Kuen <cho@slac.stanford.edu><br>
<b>Cc:</b> petsc-users@mcs.anl.gov <petsc-users@mcs.anl.gov><br>
<b>Subject:</b> Re: [petsc-users] Using PETSc GPU backend</font>
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<div dir="ltr">Run with options: -mat_type aijcusparse -vec_type cuda -log_view -options_left
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<div>The last column of the performance data (from -log_view) will be the percent flops on the GPU. Check that that is > 0.</div>
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<div>The end of the output will list the options that were used and options that were _not_ used (if any). Check that there are no options left.</div>
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<div>Mark</div>
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<div dir="ltr" class="x_x_gmail_attr">On Thu, Jun 29, 2023 at 7:50 PM Ng, Cho-Kuen via petsc-users <<a href="mailto:petsc-users@mcs.anl.gov">petsc-users@mcs.anl.gov</a>> wrote:<br>
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I installed PETSc on Perlmutter using "spack install <span style="background:rgb(255,255,255)">
petsc+cuda+zoltan</span><span style="background-color:rgb(255,255,255)">" </span>
and used it by "<span style="font-family:Arial,Helvetica,sans-serif; font-size:12pt; background:rgb(255,255,255); color:black">spack load petsc/fwge6pf</span>". Then I compiled the application code (purely CPU code) linking to the petsc package, hoping that
I can get performance improvement using the petsc GPU backend. However, the timing was the same using the same number of MPI tasks with and without GPU accelerators. Have I missed something in the process, for example, setting up PETSc options at runtime to
use the GPU backend?</div>
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Thanks,</div>
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Cho<br>
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