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/
