On Thu, Apr 30, 2009 at 8:11 AM, Tabrez Ali <span dir="ltr"><<a href="mailto:stali@purdue.edu">stali@purdue.edu</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Brad<br>
<br>
The solution at the last working step does converge and looks okay but<br>
then nothing happens and it dies. I am however experimenting with<br>
time_step and will also try to use the debugger.<br>
<br>
Btw do you know if I can use --petsc.on_error_attach_debugger when the<br>
job is submitted via PBS or should I just run it interactively?</blockquote><div><br>I do not understand why this is labeled a convergence issue. Unless I miss what<br>you mean by "die". Non-convergence will result in a bad ConvergenceReason<br>
from the solver, but nothing else. The code will continue to run.<br><br>This looks like death from a signal. With the very little information in front of<br>me, this looks like a bug in the MPI on this machine. If it was doing Sieve stuff,<br>
I would put the blame on me. But with PETSc stuff (10+ years old and used by<br>thousands of people), I put the blame on MPI or hardware for this computer.<br><br> Matt<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
...<br>
...<br>
87 KSP Residual norm 3.579491816101e-07<br>
88 KSP Residual norm 3.241876854223e-07<br>
89 KSP Residual norm 2.836307394788e-07<br>
<br>
[cli_0]: aborting job:<br>
Fatal error in MPI_Wait: Error message texts are not available<br>
[cli_1]: aborting job:<br>
Fatal error in MPI_Wait: Error message texts are not available<br>
[cli_3]: aborting job:<br>
Fatal error in MPI_Wait: Error message texts are not available<br>
[cli_2]: aborting job:<br>
Fatal error in MPI_Wait: Error message texts are not available<br>
mpiexec: Warning: tasks 0-3 exited with status 1.<br>
--pyre-start: mpiexec: exit 1<br>
/usr/rmt_share/scratch96/s/stali/pylith/bin/pylith: /usr/rmt_share/<br>
scratch96/s/stali/pylith/bin/nemesis: exit 1<br>
<br>
Tabrez<br>
<br>
On Apr 29, 2009, at 4:26 PM, Brad Aagaard wrote:<br>
<br>
> Tabrez-<br>
><br>
> You may want to set ksp_monitor=true so that you can see the<br>
> residual. If the<br>
> residual increases significantly, the solution is losing<br>
> convergence. This<br>
> can be alleviated a bit by using an absolute convergence tolerance<br>
> (ksp_atol). You probably need a slightly smaller time step or<br>
> slightly higher<br>
> quality mesh (improve the aspect ratio of the most distorted cells).<br>
><br>
> Brad<br>
><br>
><br>
> On Wednesday 29 April 2009 1:13:21 pm Tabrez Ali wrote:<br>
>> Brad<br>
>><br>
>> I think you were right. The elastic problem worked out fine. I will<br>
>> now try to play with time step (for the viscous runs)<br>
>><br>
>> Tabrez<br>
>><br>
>> On Apr 29, 2009, at 1:19 PM, Brad Aagaard wrote:<br>
>>> On Wednesday 29 April 2009 10:09:26 am Tabrez Ali wrote:<br>
>>>> Also I dont see the error until ~9000 time steps with one set of<br>
>>>> material properties but get the error at around 4000th time step<br>
>>>> with<br>
>>>> a different set of material properties (on the same mesh).<br>
>>><br>
>>> This seems to indicate a time-integration stability issue. Does the<br>
>>> one that<br>
>>> has an error after 4000 time steps have a smaller Maxwell time? You<br>
>>> might try<br>
>>> running with purely elastic properties. If that works, then you may<br>
>>> need to<br>
>>> reduce your time step.<br>
><br>
><br>
<br>
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</blockquote></div><br><br clear="all"><br>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener<br>