Understanding the timings of performance-tests

dolfinx
7

The salient timings for you are likely these:

These are called as described in the following tree

├──ZZZ Create Mesh
├──ZZZ Create facets and facet->cell connectivity
├──ZZZ FunctionSpace
├──ZZZ Assemble
│  ├──ZZZ Create boundary conditions
│  ├──ZZZ Create RHS function
│  ├──ZZZ Assemble matrix
│  └──ZZZ Assemble vector
├──ZZZ Solve 
├──ZZZ Output

You should check this in the source code looking for anything with ZZZ and not simply take my word for it.

Summarising what these timings are measuring (there’s a lot more going on than what I’m writing below, but this will give you the gist):

  • ZZZ Create Mesh: Create the mesh to be used as the spatial discretisation of the domain in the FE problem
  • ZZZ Create facets and facet->cell connectivity Compute the topology connectivity of the mesh’s graph. I.e. compute the relationship between which cells are connected to each facet.
  • ZZZ FunctionSpace Create the function space in which the FE solution will be sought along with appropriate index maps for each degree of freedom and their relationship with the mesh.
  • ZZZ Assemble Encompassing timer for:
    • ZZZ Create boundary conditions: Find the mesh’s topological indices and corresponding degree of freedom indices on which to impose boundary data in a strong Dirichlet sense.
    • ZZZ Create RHS function: This is the step computing the function f or \vec{f} in the cases where -\nabla^2 u = f and -\nabla \cdot \mathbb{C} (u) = \vec{f} (Poisson and elasticity problems, respectively).
    • ZZZ Assemble matrix: Assemble the finite element matrix \mathrm{A} underlying finite element formulation, such that we seek to later solve \mathrm{A} \vec{x} = \vec{\mathrm{b}}
    • ZZZ Assemble vector: Likewise the time to assemble the right-hand-side vector \vec{\mathrm{b}}.
  • ZZZ Solve: The time to compute the solution of the linear system, \vec{x}. This is typically the dominant stage taking the greatest computational effort.
  • ZZZ Output: The time to postprocess and output any results to disk.
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