[petsc-users] Generation, refinement of the mesh (Sieve mesh) is very slow!

[Matthew Knepley]

1) Always send the output of -log_summary when asking a performance question

2) There are implementations that are optimized for different things. Its
possible to
    optimize mesh handling for a cells-vertices mesh, but not if you need
edges and
    faces generated.

3) I am out of the country. I can look at the performance when I get back.

   Matt

On Mon, Mar 28, 2011 at 1:06 AM, fdkong <fd.kong at siat.ac.cn> wrote:

> Hi everyone
>    I have developed my application based on the sieve mesh object in the
> Pestc. And now, I encountered some  serious problems.
>  1. The generation of mesh takes a lot of time, run very slowly. The
> following code is used:
>        double lower[2] = {-1.0, -1.0};
>         double upper[2] = {1.0, 1.0};
>         int    edges[2] = {256,256};
>         mB = ALE::MeshBuilder<ALE::Mesh>::createSquareBoundary(comm, lower,
> upper, edges, debug);
>   ALE::ISieveConverter::convertMesh(*mB, *meshBd, renumbering, false);
>       ierr = PetscPrintf(PETSC_COMM_WORLD," End build convertMesh
>  \n");CHKERRQ(ierr);
>       ierr = MeshSetMesh(boundary, meshBd);CHKERRQ(ierr);
>       ierr = PetscPrintf(PETSC_COMM_WORLD," Begin build MeshGenerate
>  \n");CHKERRQ(ierr);
>
>       ierr = MeshGenerate(boundary,interpolate, &mesh);CHKERRQ(ierr);
>
>    2. The refinement of mesh is also very slow. Th code:
>      refinementLimit=0.0001;
>     if (refinementLimit > 0.0)
>     {
>       Mesh refinedMesh;
>
>       ierr = MeshRefine(mesh, refinementLimit,interpolate,
> &refinedMesh);CHKERRQ(ierr);
>       ierr = MeshDestroy(mesh);CHKERRQ(ierr);
>       mesh = refinedMesh;
>     }
>
>     3. The distribution of mesh is also very slow. The code:
>      if (size > 1)
>     {
>       Mesh parallelMesh;
>
>       //ierr = DistributeMeshnew(mesh, "chao",
> &parallelMesh);CHKERRQ(ierr);
>       ierr = DistributeMeshnew(mesh, "parmetis",
> &parallelMesh);CHKERRQ(ierr);
>       ierr = MeshDestroy(mesh);CHKERRQ(ierr);
>       mesh = parallelMesh;
>     }.
>
>     Does anyone encounter these similar problem? If anyone can help, thank
> you very much!
>
>    And I wonder to consult which parallel mesh can work  with Petsc very
> well, when we develop some complex problem?
>
>
> ------------------
> Fande Kong
> ShenZhen Institutes of Advanced Technology
> Chinese Academy of Sciences
>
>



-- 
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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