A 3D example of KSPSolve?

Fri Feb 9 21:23:10 CST 2007

Sorry that is not informative.
So I decide to attach the 5 files for NP=1,2,4,8,16
for 
the 400,000 finite element case.

Please note that the simulation runs over 100 steps.
The 1st step is first order update, named as stage 1.
The rest 99 steps are second order updates. Within
that, stage 2-9 are created for the 8 stages of a
second order update. We should concentrate on the
second order updates. So four calls to KSPSolve in the
log file are important, in stage 4,5,6,and 8
separately.
Pleaes let me know if you need any other information
or explanation.
Thank you very much.

Shi
--- Matthew Knepley <knepley at gmail.com> wrote:

> You really have to give us the log summary output.
> None of the relevant
> numbers are in your summary.
> 
>  Thanks,
> 
>    Matt
> 
> On 2/9/07, Shi Jin <jinzishuai at yahoo.com> wrote:
> >
> > Dear Barry,
> >
> > Thank you.
> > I actually have done the staging already.
> > I summarized the timing of the runs in google
> online
> > spreadsheets. I have two runs.
> > 1. with 400,000 finite elements:
> >
>
http://spreadsheets.google.com/pub?key=pZHoqlL60quZeDZlucTjEIA
> > 2. with 1,600,000 finite elements:
> >
>
http://spreadsheets.google.com/pub?key=pZHoqlL60quZcCVLAqmzqQQ
> >
> > If you can take a look at them and give me some
> > advice, I will be deeply grateful.
> >
> > Shi
> > --- Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> > >
> > >   NO, NO, don't spend time stripping your code!
> > > Unproductive
> > >
> > >   See the manul pages for
> PetscLogStageRegister(),
> > > PetscLogStagePush() and
> > > PetscLogStagePop(). All you need to do is
> maintain a
> > > seperate stage for each
> > > of your KSPSolves; in your case you'll create 3
> > > stages.
> > >
> > >    Barry
> > >
> > > On Fri, 9 Feb 2007, Shi Jin wrote:
> > >
> > > > Thank you.
> > > > But my code has 10 calls to KSPSolve of three
> > > > different linear systems at each time update.
> > > Should I
> > > > strip it down to a single KSPSolve so that it
> is
> > > > easier to analysis? I might have the code dump
> the
> > > > Matrix and vector and write another code to
> read
> > > them
> > > > into and call KSPSolve. I don't know whether
> this
> > > is
> > > > worth doing  or should I just send in the
> messy
> > > log
> > > > file of the whole run.
> > > > Thanks for any advice.
> > > >
> > > > Shi
> > > >
> > > > --- Barry Smith <bsmith at mcs.anl.gov> wrote:
> > > >
> > > > >
> > > > >   Shi,
> > > > >
> > > > >    There is never a better test problem then
> > > your
> > > > > actual problem.
> > > > > Send the results from running on 1, 4, and 8
> > > > > processes with the options
> > > > > -log_summary -ksp_view (use the optimized
> > > version of
> > > > > PETSc (running
> > > > > config/configure.py --with-debugging=0))
> > > > >
> > > > >   Barry
> > > > >
> > > > >
> > > > > On Fri, 9 Feb 2007, Shi Jin wrote:
> > > > >
> > > > > > Hi there,
> > > > > >
> > > > > > I am tuning our 3D FEM CFD code written
> with
> > > > > PETSc.
> > > > > > The code doesn't scale very well. For
> example,
> > > > > with 8
> > > > > > processes on a linux cluster, the speedup
> we
> > > > > achieve
> > > > > > with a fairly large problem size(million
> of
> > > > > elements)
> > > > > > is only 3 to 4 using the Congugate
> gradient
> > > > > solver. We
> > > > > > can achieve a speed up of a 6.5 using a
> GMRes
> > > > > solver
> > > > > > but the wall clock time of a GMRes is
> longer
> > > than
> > > > > a CG
> > > > > > solver which indicates that CG is the
> faster
> > > > > solver
> > > > > > and it scales not as good as GMRes. Is
> this
> > > > > generally
> > > > > > true?
> > > > > >
> > > > > > I then went to the examples and find a 2D
> > > example
> > > > > of
> > > > > > KSPSolve (ex2.c). I let the code ran with
> a
> > > > > 1000x1000
> > > > > > mesh and get a linear scaling of the CG
> solver
> > > and
> > > > > a
> > > > > > super linear scaling of the GMRes. These
> are
> > > both
> > > > > much
> > > > > > better than our code. However, I think the
> 2D
> > > > > nature
> > > > > > of the sample problem might help the
> scaling
> > > of
> > > > > the
> > > > > > code. So I would like to try some 3D
> example
> > > using
> > > > > the
> > > > > > KSPSolve. Unfortunately, I couldn't find
> such
> > > an
> > > > > > example either in the
> > > > > src/ksp/ksp/examples/tutorials
> > > > > > directory or by google search. There are a
> > > couple
> > > > > of
> > > > > > 3D examples in the
> > > src/ksp/ksp/examples/tutorials
> > > > > but
> > > > > > they   are about the SNES not KSPSolve. If
> > > anyone
> > > > > can
> > > > > > provide me with such an example, I would
> > > really
> > > > > > appreciate it.
> > > > > > Thanks a lot.
> > > > > >
> > > > > > Shi
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> >
>
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