On Sun, Sep 2, 2012 at 12:24 PM, Birendra jha <span dir="ltr"><<a href="mailto:bjha7333@yahoo.com" target="_blank">bjha7333@yahoo.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear developers<br>
<br>
I am trying to run my Pylith simulation faster. Right now it takes about 3 min for Linear solve (using default KSP solver, about 960 iterations) and 3 min for integrating residual. I have about 190000 hex cells (mesh is very refined in the center and becomes coarse outward). No faults. Elastic materials. I used non-uniform user specified timesteps.<br>
<br>
I thought of following options:<br></blockquote><div><br></div><div>(0) Is this an optimized build?</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
(1) Try different solver. I am thinking of using field split preconditioner with multigrid, as in tet4/step02.cfg.<br></blockquote><div><br></div><div>If there are no faults, FieldSplit makes no sense. Just use ML. It should take < 10 iterations.</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
(2) Switch from vtk to hdf5 output<br></blockquote><div><br></div><div>Definitely, also back off the frequency of output.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
(3) Run in parallel. I am looking into running it using sge. Or just running it on one multicore machine.<br></blockquote><div><br></div><div>Do bother with this until you figure out how to run in serial.</div><div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
(4) Increase linear solve tolerance from 1E-12 to 1E-11.<br></blockquote><div><br></div><div>I would try and gauge what tolerance you need by doing some manufactured solutions.</div><div><br></div><div> Matt</div><div>
<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
(5) Fix timestep.<br>
<br>
Are these good options to consider?<br>
<br>
I have a question on (5). Manual says<br>
Warning: Changing the time step requires recomputing the Jacobian of the system, which can greatly increase the runtime if the time-step size changes frequently.<br>
<br>
Where does this happen in the program, i.e a change in dt setting needNewJacobian=true? I ask this because I could not find message on the stdout about reforming Jacobian when I am using non-uniform dt (it is possible that I missed it, the timesteps remains constant for a while then changes then becomes constant again).<br>
<br>
Thanks and regards<br>
Birendra<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <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>