Comment on runtimes.

git-svn-id: https://svn.dealii.org/trunk@15924 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/examples/step-22/doc/results.dox b/deal.II/examples/step-22/doc/results.dox
index 53888907d61dc4d98de7e6b74c3e48af84d57f59..d324710edeac3a63c6059ff726488e334c949b0a 100644 (file)
--- a/deal.II/examples/step-22/doc/results.dox
+++ b/deal.II/examples/step-22/doc/results.dox
@@ -176,21 +176,18 @@ Refinement cycle 5
    Assembling...
    Computing preconditioner...
    Solving...  14 outer CG Schur complement iterations for pressure.
-
-Refinement cycle 6
-   Number of active cells: 170720
-   Number of degrees of freedom: 4625150 (4432407+192743)
-   Assembling...
-   Computing preconditioner...
-   Solving...  15 outer CG Schur complement iterations for pressure.
 @endcode
 
 Again, we see that the number of outer iterations does not increase as
 we refine the mesh. Nevertheless, the compute time increases
 significantly: for each of the iterations above separately, it takes a
-few seconds, a few seconds, 1min, 5min, 29min, 3h12min, and 21h39min
-for the finest level with more than 4.5 million unknowns. This
-superlinear (in the number of unknowns) increase is due to the fact
+few seconds, a few seconds, 1min, 5min, 21min, and 1h35. (One level
+more can be run on machines with more memory, though one may have to
+replace the BlockCompressedSetSparsityPattern class by the
+BlockCompressedSparsityPattern class as the former needs significantly
+more memory and becomes the bottleneck; the latter class, however, has
+a superlinear runtime complexity.) This overall
+superlinear (in the number of unknowns) increase in runtime is due to the fact
 that our inner solver is not ${\cal O}(N)$: a simple experiment shows
 that as we keep refining the mesh, the average number of
 ILU-preconditioned CG iterations to invert the velocity-velocity block