Print global number of cells and dofs

[benegee]

Resolves #1616

[github-actions[bot]]

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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 93.88464% with 88 lines in your changes are missing coverage. Please review.

Project coverage is 96.11%. Comparing base (909abb4) to head (bded959). Report is 58 commits behind head on main.

Files	Patch %	Lines
...ation/paired_explicit_runge_kutta/methods_PERK2.jl	85.44%	23 Missing :warning:
src/callbacks_step/analysis_surface_integral_2d.jl	91.04%	12 Missing :warning:
src/equations/linearized_euler_1d.jl	76.60%	11 Missing :warning:
src/equations/linearized_euler_3d.jl	94.74%	5 Missing :warning:
src/Trixi.jl	0.00%	4 Missing :warning:
src/meshes/structured_mesh_view.jl	91.30%	4 Missing :warning:
src/meshes/t8code_mesh.jl	96.04%	4 Missing :warning:
src/solvers/dgsem_tree/subcell_limiters.jl	88.89%	4 Missing :warning:
src/callbacks_step/analysis.jl	86.96%	3 Missing :warning:
...em/elixir_linearizedeuler_characteristic_system.jl	93.10%	2 Missing :warning:
... and 10 more

Additional details and impacted files

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[JoshuaLampert]

What about other mesh types like the TreeMesh? Does it print the local or global number of cells (see here)?

[ranocha]

The TreeMesh replicates all cell info on all ranks. Thus, it prints the global info.

[sloede]

@benegee Please note that you should also adapt the output of the AMR output, probably in these three functions: https://github.com/trixi-framework/Trixi.jl/blob/8a9fc7baeca9807de185592d5cb8d60040a24f09/src/callbacks_step/analysis.jl#L494 https://github.com/trixi-framework/Trixi.jl/blob/8a9fc7baeca9807de185592d5cb8d60040a24f09/src/callbacks_step/analysis.jl#L520 https://github.com/trixi-framework/Trixi.jl/blob/8a9fc7baeca9807de185592d5cb8d60040a24f09/src/callbacks_step/analysis.jl#L554

Otherwise we get a global element count but only rank-0 information on AMR, which is bound to cause confusion IMHO

[benegee]

True! I realized this in the meantime as well, but have not finished the MPI syncing of element counts.

[sloede]

True! I realized this in the meantime as well, but have not finished the MPI syncing of element counts.

Optimally, you'll use an implementation that only requires a single additional MPI_Reduce call.

[benegee]

Summary

Global number of elements and dofs

nodofsglobal and nelementsglobal are now used in the Base.show output of semidiscretizations and meshes, and of the AnalysisCallback.

For DG, nodofsglobal already relied on nelementsglobal:

https://github.com/trixi-framework/Trixi.jl/blob/76719a85e0226ba9883dcf3817c6afe8daffb3f6/src/solvers/dg.jl#L461-L463

and nelementsglobal was already MPI aware:

https://github.com/trixi-framework/Trixi.jl/blob/76719a85e0226ba9883dcf3817c6afe8daffb3f6/src/solvers/dg.jl#L520-L522

For DGMulti, ndofsglobal was already MPI aware as well:

https://github.com/trixi-framework/Trixi.jl/blob/76719a85e0226ba9883dcf3817c6afe8daffb3f6/src/callbacks_step/analysis_dgmulti.jl#L188-L194

I now added nelementsglobal in analogy.

New solver types would now have to implement ndofsglobal and nelementsglobal.

Global number of elements per level

The local element numbers per level are now summed up across all ranks before being printed on rank 0. In order to not having to synchronize the minimum and maximum element levels in advance, I took this information from the AMRController. This currently works but would require new controllers to provide the same information. If you see a better solution, please give me a hint.

[sloede]

Thanks a lot for tackling this @benegee! This makes Trixi.jl much more usable in parallel 💪