On Dec 2, 2011, at 5:20 PM, Dave Nystrom wrote:
> Hi Jed,
>
> I tried your suggestion below and it made a huge improvement. Instead of
> taking about 6x as long per linear solve as using LU, it now takes between
> 35% to 80% longer than LU depending on which of the different linear solves
> I'm
PETSc has allocated. Or use a heap profiler.
Some day we will write a better tool that tracks stack traces for large
allocations only.
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ry my code is using.
>
1. Check -log_summary to see which object types the large allocations are
coming from.
2. What are you running?
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Jed Brown writes:
> On Fri, Dec 2, 2011 at 21:06, Dave Nystrom tachyonlogic.com>wrote:
>
> > It seems that whenever I am running my code with petsc and run top on linux
> > it reports that my code is running something like 24-25 GB of memory, even
> > if I am running a smallish problem. Is
It seems that whenever I am running my code with petsc and run top on linux
it reports that my code is running something like 24-25 GB of memory, even if
I am running a smallish problem. Is this normal? I just had a problem
terminate because it ran out of memory and I had no idea that I was pushi
Never mind. I was looking in the wrong place.
Dave Nystrom writes:
> I was looking for GAMG on the development section of the online web site and
> can't seem to find any reference to it. Is there documentation available on
> GAMG?
>
> Thanks,
>
> Dave
I was looking for GAMG on the development section of the online web site and
can't seem to find any reference to it. Is there documentation available on
GAMG?
Thanks,
Dave
-6893 (home)
> > skype: dave.nystrom76
> > email: dnystrom1 at comcast.net
> > smail: 219 Loma del Escolar
> >Los Alamos, NM 87544
>
--
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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On Dec 2, 2011, at 6:06 PM, Dave Nystrom wrote:
> Mark F. Adams writes:
>> It sounds like you have a symmetric positive definite systems like du/dt -
>> div(alpha(x) grad)u. The du/dt term makes the systems easier to solve.
>> I'm guessing your hard system does not have this mass term and so is
o provide additional info and am planning on packaging
> up a
> > > couple of examples of the matrix and rhs for people I am interacting
> with
> > > at Tech-X and EMPhotonics. So I'd be happy to provide the matrix
> > > examples for this forum as well if anyone wants a copy.
> > >
> > > Thanks,
> > >
> > > Dave
> > >
> > > --
> > > Dave Nystrom
> > >
> > > phone: 505-661-9943 (home office)
> > > 505-662-6893 (home)
> > > skype: dave.nystrom76
> > > email: dnystrom1 at comcast.net
> > > smail: 219 Loma del Escolar
> > > Los Alamos, NM 87544
>
--
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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>
> > wrote:
> >
> >
> >
> > Unstructured quads. But it can be mixed in
> >
> >
> >
> > the future.
> >
> >
> >
> > Do you only need cells and vertices, or do you need
> >
> > faces?
>
--
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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I never received any reply to this question but would very much appreciate
one. Not sure if it fell through the cracks.
Thanks,
Dave
Dave Nystrom writes:
> I have a 2d resistive mhd code interfaced to petsc. The code has seven
> different linear solves per timestep and these linear solves co
Hi Barry,
Barry Smith writes:
> Dave,
>
> Does this come from a structured 2d grid? If so, then in addition to
> algebraic multigrid you could consider geometric multigrid which could
> work very well.
Yes, this problem comes from spatial discretization on a uniform structured
2d grid. So
Mark F. Adams writes:
> It sounds like you have a symmetric positive definite systems like du/dt -
> div(alpha(x) grad)u. The du/dt term makes the systems easier to solve.
> I'm guessing your hard system does not have this mass term and so is
> purely elliptic. Multigrid is well suited for th
Shrirang Abhyankar writes:
> Dave,
>
> I doubt if you would see a significant performance improvement in linear
> solves using pthreads since currently we have support for threaded seq and
> mpi vectors only. The pthread work is an ongoing work so it might be also
> unstable at times. I su
Matthew Knepley writes:
> On Wed, Nov 30, 2011 at 12:41 AM, Dave Nystrom comcast.net>wrote:
>
> > I have a linear system in a code that I have interfaced to petsc that is
> > taking about 80 percent of the run time per timestep. This linear system
> > is a symmetric block banded matrix wher
Hi Jed,
I tried your suggestion below and it made a huge improvement. Instead of
taking about 6x as long per linear solve as using LU, it now takes between
35% to 80% longer than LU depending on which of the different linear solves
I'm measuring. So that is a big improvement. Is there a reason
; > VSB-Technical University of Ostrava
> > 17.listopadu 15/2172
> > 708 33 Ostrava-Poruba
> > Czech Republic
> >
> >
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