Re: [Libmesh-devel] reduced_basis_ex6 fails on ParallelMesh

[David K. <dkn...@se...>]

On 10/31/2012 05:33 PM, Roy Stogner wrote:
>
> And it doesn't look like it's ParallelMesh's fault.
>
> RBEIMConstruction::evaluate_mesh_function is querying a MeshFunction
> object, and that query returns the _out_of_mesh_value (an empty
> DenseVector by default) if it's asked for the value of a point that's
> not within any active local or active ghosted elements.
>
> Even with SerialMesh, this would normally fail, except that
> RBEIMConstruction built a serialized solution vector to hand to the
> MeshFunction, so results should be correct but performance should
> scale poorly.
>
> enrich_RB_space() and update_RB_system_matrices() are doing a localize
> to that serialized vector, so they must already be parallel_only
> methods - would it be possible to change them to only query local
> elements, and then if necessary sync the resulting data afterwards?
>
> For now I'm going to disable reduced_basis_ex6 in the --enable-parmesh
> case.

OK, let me fix this all up, but in the meantime disabling parmesh for 
rb_ex6 is good.

I haven't used this functionality on large problems yet, so the scaling 
hasn't hit me, but good to fix it sooner rather than later. Thanks!

David