[petsc-users] Poor multigrid convergence in parallel

[Jed Brown]

Sorry about not following up.  I also find these results peculiar.

Lawrence Mitchell <lawrence.mitchell at imperial.ac.uk> writes:
> So I'm sort of none-the-wiser.  I'm a little bit at a loss as to why
> this occurs, but either switching to Richardson+SOR or Cheby/SOR with
> more that one SOR sweep appears to fix the problems, so I might just
> punt for now.

What discretization and mesh is this running on?  Is there something
special about the decomposition with 2 subdomains?  Are the Chebyshev
estimates far from converging?  Something is funky because if you have a
discretization with good h-ellipticity, reliable convergence should not
be a problem.
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