[Beowulf] WRF model on linux cluster: Mpi problem

Vincent Diepeveen diep at xs4all.nl
Thu Jun 30 03:44:22 PDT 2005

Hello Federico,

Hope you can find contacts to colleges.

A few questions.
  a) what kind of interconnects does the cluster have (networkcards and
which type?)
  b) if you run a simulation that eats a few hours instead of a few seconds,
     do you get the same speed outcome difference?

I see the program is pretty big for open source calculating software, about
1.9MB fortran code, so bit time consuming to figure out for someone who
isn't a non-meteorological expert.

E:\wrf>dir *.f* /s /p
     Total Files Listed:
             141 File(s)      1,972,938 bytes

Best regards,

At 06:56 PM 6/29/2005 +0200, federico.ceccarelli wrote:
>I would like to get in touch with people running numerical meteorological
>models  on a linux cluster (16cpu) , distributed memory (1Gb every node),
>diskless nodes, Gigabit lan, mpich and openmosix.
>I'm tring to run WRF model but the mpi version parallelized on 4, 8, or 16
>nodes runs slower than the single node one! It runs correctly but so slow...
>When I run wrf.exe on a single processor the cpu time for every timestep is
>about 10s for my configuration.
>When I switch to np=4, 8 or 16 the cpu time for a single step sometimes its
>faster (as It should always be, for example 3sec for 4 cpu ) but often it is
>slower and slower (60sec and more!). The overall time of the simulation is
>bigger than for the single node run...
>anyone have experienced the same problem?
>thanks in advance to everybody...
>Dr. Federico Ceccarelli (PhD)
>     TechCom snc
>Via di Sottoripa 1-18
>16124 Genova - Italia
>Tel: +39 010 860 5664
>Fax: +39 010 860 5691
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