bug ? number of processor, coarse and fine DA for DMMG

[Barry Smith]

   This is a limitation in the way the interpolation is computed.  It  
is not really an error. There is no easy way to extend the code for  
these other configurations.


    Barry

On Sep 4, 2009, at 7:39 AM, nicolas aunai wrote:

> Hello,
>
>
> I have a code that uses the DMMG objet for a linear problem. The DA I
> create for the coarse grid is DA_XPERIODIC and 2D. I let petsc decide
> for the number of processors in each direction.
>
> I have a problem which depends on the number of processors I use.
> If I want a 1024x1025 grid with 4 levels, the coarsest grid will be
> 128x129 with the default refinement factor.
>
> Everything seems to work fine when I run with 1, 2, 3, 4, 6, 8...
> processors... but 5, 7, 11 proc fail with the following error :
>
>
> nicolas at lx-nau:~/code/tests/petsc/dmmg$ mpiexec -n 5 ./inertia6
> -ksp_type gmres -pc_type sor -ksp_rtol 1e-9
>
> size of the coarse level : 128 129
> debug 1, number of proc in each dir. : 1 5
>
> [3]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> [3]PETSC ERROR: Arguments are incompatible!
> [3]PETSC ERROR: Processor's coarse DA must lie over fine DA
>    j_start 615 j_c 307 j_start_ghost_c 308!
> [3]PETSC ERROR:
> ------------------------------------------------------------------------
> [3]PETSC ERROR: Petsc Release Version 3.0.0, Patch 7, Mon Jul  6
> 11:33:34 CDT 2009
> [3]PETSC ERROR: See docs/changes/index.html for recent updates.
> [3]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
> [3]PETSC ERROR: See docs/index.html for manual pages.
> [3]PETSC ERROR:
> ------------------------------------------------------------------------
> [3]PETSC ERROR: ./inertia6 on a linux-gnu named lx-nau by nicolas Fri
> Sep  4 14:39:27 2009
> [3]PETSC ERROR: Libraries linked from
> /home/nicolas/bin/petsc-3.0.0-p7/linux-gnu-debug/lib
> [3]PETSC ERROR: Configure run at Mon Aug 17 11:34:27 2009
> [3]PETSC ERROR: Configure options --with-cc=gcc --with-fc=gfortran
> --download-f-blas-lapack=1 --download-mpich=1
> PETSC_ARCH=linux-gnu-debug --with-shared=0
> [3]PETSC ERROR:
> ------------------------------------------------------------------------
> [3]PETSC ERROR: DAGetInterpolation_2D_Q1() line 280 in src/dm/da/src/ 
> dainterp.c
> [3]PETSC ERROR: DAGetInterpolation() line 879 in src/dm/da/src/ 
> dainterp.c
> [3]PETSC ERROR: DMGetInterpolation() line 144 in src/dm/da/utils/dm.c
> [3]PETSC ERROR: DMMGSetDM() line 309 in src/snes/utils/damg.c
>
>
>
> it seems that the error come from the routine DMMGSetDM, when petsc
> build the restriction/interpolation operators... but I can't figure
> out why I couln't use 5 processors with this grid size ?
>
> if the code is needed, it is here : http://nico.aunai.free.fr/inertia6.c
>
>
> Thx for your help
>
> Nico