A 3D example of KSPSolve?

[Shi Jin]

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
> > > > 
> > > > 
> > > >  
> > > >
> > >
> >
>
____________________________________________________________________________________
> > > > Finding fabulous fares is fun.  
> > > > Let Yahoo! FareChase search your favorite
> travel
> > > sites to find flight and hotel bargains.
> > > >
> http://farechase.yahoo.com/promo-generic-14795097
> > > > 
> > > > 
> > > 
> > > 
> > 
> > 
> > 
> >  
> >
>
____________________________________________________________________________________
> > 8:00? 8:25? 8:40? Find a flick in no time 
> > with the Yahoo! Search movie showtime shortcut.
> > http://tools.search.yahoo.com/shortcuts/#news
> > 
> > 
> 
> 



 
____________________________________________________________________________________
Looking for earth-friendly autos? 
Browse Top Cars by "Green Rating" at Yahoo! Autos' Green Center.
http://autos.yahoo.com/green_center/