[petsc-users] Amortizing calls to PetscOptionsFindPair_Private()

Matthew Knepley knepley at gmail.com
Fri Jan 15 19:40:51 CST 2016

On Fri, Jan 15, 2016 at 6:15 PM, Bhalla, Amneet Pal S <amneetb at live.unc.edu>

> On Jan 15, 2016, at 3:53 PM, Jed Brown <jed at jedbrown.org> wrote:
> Do you need to create new objects versus merely resetting them?  I
> suspect that calling KSPReset() between timesteps instead of creating a
> new object and calling KSPSetFromOptions() will fix your performance
> woes.
> We definitely need to destroy Mat associated with KSP everytime. This is a
> dynamic fluid-structure
> interaction problem on AMR grid, where the Cartesian grid and the
> structure moves at every timestep.
> Is it possible to reset a KSP with a different Mat? Are you suggesting to
> call KSPCreate() and
> KSPSetFromOptions() only once at the beginning of simulation, KSPReset()
> after every timestep,
> and KSPDestroy() at the end of the simulation?

That is how KSPReset() is supposed to work, but no one is really exercising
it now. I am inclined to try
Barry's experiment first, since this may have bugs that we have not yet
discovered. However, Jed is
correct that this is probably the best design.


What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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