[petsc-users] EPSSolve in a loop

[Dharmendar Reddy]

On Fri, May 3, 2013 at 10:20 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> Dharmendar Reddy <dharmareddy84 at gmail.com> writes:
>
> > Hello,
> >           I see an interesting behavior when i call EPSSolve in a loop.
> Can
> > you help me figure out whats going on ?
> >
> > I have a setup like this to solve a A x = lambda B x   (Generalized
> > Hermitian problem)
> >
> > type eigenSolver_t
> >   EPS :: eps
> >
> > end type eigenSolver_t
> >
> > the type has bound procedure which calls  EPSSetOperators and EPSSolve
> when
> > eigenSolver%solve() is called
> >
> > Now i run a for loop
> >
> > do ic=1,111
> >   call eigenSolver(ic)%solve()
> > end do
> >
> > I print the time for each solve.  The operators A,B =A1,B1 for ic=1 to 50
> > A2,B2 for ic=51 to 80  and A3,B3 for ic=81 to 111
> >
> > Now i see that time per solve per ic is almost constant when i use
> > -eps_type lapack.
>
> How do you figure?  It looks like it increases by more than an order of
> magnitude.
>
>    You are right, The time per solve increases in both case, see the
attached plot.

  I have attached the stage wise log_summary .


> Always send -log_summary output when asking about performance.  In this
> case, it would be nice to use a different stage to log each solve.
>
> > But for, defualt solver, time per solve seem to increase with increasing
> > ic. Have look at the attached timing information.
> >
> > Also, Time per solve using lapack is lower than any of the iterative
> > solvers i have tried. Problem size is about 100 x 100, operators are
> > tri-diagonal.
>
> I'm not surprised.  That problem is tiny.
>



-- 
-----------------------------------------------------
Dharmendar Reddy Palle
Graduate Student
Microelectronics Research center,
University of Texas at Austin,
10100 Burnet Road, Bldg. 160
MER 2.608F, TX 78758-4445
e-mail: dharmareddy84 at gmail.com
Phone: +1-512-350-9082
United States of America.
Homepage: https://webspace.utexas.edu/~dpr342
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