[petsc-users] Strange GAMG performance for mixed FE formulation

[Lawrence Mitchell]

> On 4 Mar 2016, at 15:24, Justin Chang <jychang48 at gmail.com> wrote:
> 
> So with -pc_gamg_square_graph 10 I get the following:

Because you're using gamg inside the fieldsplit, I think you need:

-fieldsplit_1_pc_gamg_square_graph 10



> [0] PCSetUp_GAMG(): level 0) N=48000, n data rows=1, n data cols=1, nnz/row (ave)=9, np=1
> [0] PCGAMGFilterGraph(): 	 55.7114% nnz after filtering, with threshold 0., 8.79533 nnz ave. (N=48000)
> [0] PCGAMGCoarsen_AGG(): Square Graph on level 1 of 1 to square
                                                 ^^^^^

Cheers,

Lawrence
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