Hello Rossi,
Two questions:
1) Which error estimator/indicator are you using to mark elements for
refinement ?
2) Can you send the perfLog output from libMesh ? You might need to
recompile libMesh with the option --enable-perflog.
Looks something like this:
-----------------------------------------------------------------------------------------------------------------
| libMesh Performance: Alive time=0.013423, Active time=0.007095
|
-----------------------------------------------------------------------------------------------------------------
| Event nCalls Total Time Avg Time
Total Time Avg Time % of Active Time |
| w/o Sub w/o Sub
With Sub With Sub w/o S With S |
|-----------------------------------------------------------------------------------------------------------------|
|
|
|
|
| DofMap
|
| add_neighbors_to_send_list() 6 0.0001 0.000012
0.0001 0.000012 1.01 1.01 |
| build_sparsity() 6 0.0002 0.000033
0.0011 0.000187 2.78 15.84 |
| create_dof_constraints() 6 0.0000 0.000001
0.0000 0.000001 0.07 0.07 |
| distribute_dofs() 6 0.0001 0.000025
0.0004 0.000066 2.09 5.57 |
| dof_indices() 688 0.0010 0.000001
0.0010 0.000001 14.36 14.36 |
| old_dof_indices() 300 0.0001 0.000000
0.0001 0.000000 0.96 0.96 |
| prepare_send_list() 7 0.0000 0.000000
0.0000 0.000000 0.01 0.01 |
| reinit() 6 0.0002 0.000041
0.0002 0.000041 3.48 3.48 |
|
|
| EquationSystems
|
| build_solution_vector() 1 0.0001 0.000056
0.0001 0.000064 0.79 0.90 |
Thanks.
On Wed, Apr 26, 2017 at 10:09 PM, Rossi, Simone <[email protected]>
wrote:
> Dear Roy, dear Paul, dear all,
> I am testing AMR in libmesh using simple linear elements.
> My test case is a propagating front described by a reaction-diffusion
> equation with a cubic bistable reaction term.
> I followed the adaptivity examples to create this test case.
>
> The run times for 100 timesteps using AMR can be more than 10 times slower
> than when using a fine uniform grid.
> For example, with a 16 x 16 x 16 uniform grid, 100 iterations take about
> 18 seconds with a single processor.
> With AMR, using a 2 x 2 x 2 grid and 3 levels of refinement, 100
> iterations take about 800 seconds.
>
> I’m attaching the code I’m using.
> Without AMR, I build the matrix ( mass + dt * stiffness ) once and I
> update the rhs at every timestep.
> Conversely, with AMR I am building the matrix and the rhs at every
> timestep for all the refinement levels.
> Do you have any suggestions?
>
> Thanks a lot for your help,
> All the best,
> Simone
>
>
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>
--
Vikram Garg
Postdoctoral Associate
The University of Texas at Austin
http://vikramvgarg.wordpress.com/
http://www.runforindia.org/runners/vikramg
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