[petsc-users] about speed

[Barry Smith]

   ./configure an optimized version of PETSc (that is with the ./configure flag of --with-debugging=0) and run with -log_summary to get a summary of where it is spending the time. This will give you a better idea of why it is taking so long.

   Barry

On Jul 26, 2010, at 2:49 PM, Xuan YU wrote:

> Hi,
> 
> I am using TS solving a nonlinear problem. I created an approximate data structure for Jacobian matrix to be used with matcoloring, my MatFDColoringView is like this:
> <Picture 1.png>
> 
> But the speed of code is too slow than what I expected. Only 10 time step costs 11seconds!
> 
> What's wrong with my code? How can I speed up?
> 
> Thanks!
> 
> This is the ts_view result.
> 
> TS Object:
>  type: beuler
>  maximum steps=100
>  maximum time=10
>  total number of nonlinear solver iterations=186
>  total number of linear solver iterations=423
>  SNES Object:
>    type: ls
>      line search variant: SNESLineSearchCubic
>      alpha=0.0001, maxstep=1e+08, minlambda=1e-12
>    maximum iterations=50, maximum function evaluations=10000
>    tolerances: relative=1e-08, absolute=1e-50, solution=1e-08
>    total number of linear solver iterations=1
>    total number of function evaluations=19
>    KSP Object:
>      type: gmres
>        GMRES: restart=30, using Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement
>        GMRES: happy breakdown tolerance 1e-30
>      maximum iterations=10000, initial guess is zero
>      tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
>      left preconditioning
>      using PRECONDITIONED norm type for convergence test
>    PC Object:
>      type: ilu
>        ILU: out-of-place factorization
>        0 levels of fill
>        tolerance for zero pivot 1e-12
>        using diagonal shift to prevent zero pivot
>        matrix ordering: natural
>        factor fill ratio given 1, needed 1
>          Factored matrix follows:
>            Matrix Object:
>              type=seqaij, rows=1838, cols=1838
>              package used to perform factorization: petsc
>              total: nonzeros=8464, allocated nonzeros=8464
>              total number of mallocs used during MatSetValues calls =0
>                not using I-node routines
>      linear system matrix = precond matrix:
>      Matrix Object:
>        type=seqaij, rows=1838, cols=1838
>        total: nonzeros=8464, allocated nonzeros=9745
>        total number of mallocs used during MatSetValues calls =37
>          not using I-node routines
> 
> 
> Xuan YU
> xxy113 at psu.edu
> 
> 
> 
>