[petsc-dev] [Fortran] MatLoad() error: MatLoad is not supported for type: mpiaij!

[Leo van Kampenhout]

Thanks. Following this conversation closely, i have already built petsc with
--with-debugging=0 and found that then thing work better there. Until there
is a ultimate fix I'm perfectly happy with that.

Even on my cluster, I can now run the program for 2,4,8 cores. But there is
always a catch... with 10 cores, GMRES breaks down! (see below) Sorry to
bother you with this, it seems unrelated at first sight. Should I issue a
new thread for this?

Regards, Leo

[5]PETSC ERROR: --------------------- Error Message
------------------------------------
[5]PETSC ERROR: Nonconforming object sizes!
[5]PETSC ERROR: Mat mat,Vec y: local dim 210161 213282!
[5]PETSC ERROR:
------------------------------------------------------------------------
[5]PETSC ERROR: Petsc Development HG revision:
6da7d8c5aaa81099861622f4e6bf1087652253a7  HG Date: Fri Sep 03 15:06:40 2010
+0200
[5]PETSC ERROR: See docs/changes/index.html for recent updates.
[5]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
[5]PETSC ERROR: See docs/index.html for manual pages.
[5]PETSC ERROR:
------------------------------------------------------------------------
[5]PETSC ERROR: ./main on a linux-opt named node164 by s1459295    Fri Sep
3 17:44:26 2010
[5]PETSC ERROR: Libraries linked from
/home/s1459295/install/petsc-dev/linux-optimized/lib
[5]PETSC ERROR: Configure run at Fri Sep  3 15:28:20 2010
[5]PETSC ERROR: Configure options --with-debugging=0
[5]PETSC ERROR:
------------------------------------------------------------------------
[5]PETSC ERROR: MatMult() line 1976 in src/mat/interface/matrix.c
[5]PETSC ERROR: KSPInitialResidual() line 55 in
src/ksp/ksp/interface/itres.c
[5]PETSC ERROR: KSPSolve_GMRES() line 236 in src/ksp/ksp/impls/gmres/gmres.c
[5]PETSC ERROR: KSPSolve() line 427 in src/ksp/ksp/interface/itfunc.c





2010/9/3 Jed Brown <jed at 59a2.org>

> On Fri, 3 Sep 2010 09:15:09 -0600 (GMT-06:00), Shri <abhyshr at mcs.anl.gov>
> wrote:
> > Leo,
> >     Jed and I both tried running a MatLoad example (see
> src/dm/da/examples/tests/ex35.c) with petsc configured in debug mode and had
> issues running it with your grid size 202 X 102 X 102. This example runs in
> a reasonable amount of time with the optimized petsc build.
> > I suggest running your code on a smaller grid (100 X100 X 100 seems to
> work fine in the debug mode) for now, get it working and then using the
> optimized petsc build (--debugging=0) for the large grid size.
>
> I wrote an improved sort that doesn't have this bad behavior, but I'm
> trying to figure out why the old one is okay in optimized mode.  See
> here:
>
>  http://gist.github.com/563948
>
> The MEDIAN macro chooses the median of the first, last, and middle
> element in the segment.  Performance looks like
>
>  FAST -O1: 2.0 seconds
>  FAST -O0: 5 seconds
>  SLOW -O1: 2.3 seconds
>  SLOW -O0: more than an hour
>
> SLOW, which is basically the old implementation does a lot of shuffling
> with the array and ends up hitting a bad case for quicksort (even with
> the median choice).  What I don't understand, is that apparently
> building SLOW with -O1 transforms the algorithm into something
> asymptotically faster.  The assembly is a few hundred lines, and it's
> not obvious to me what this transform would be.
>
> Jed
>
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