[GRASS5] Parallel GRASS modules for high performance

[Helena Mitasova]

You must have missed a lot in your search - numerous parallel versions 
of interpolation and other modules
have been written since 1993, there should be a link to parallel idw on 
the grass web site and a parallel
version of the s.surf.rst module is here:
http://skagit.meas.ncsu.edu/~helena/grasswork/grasscontrib/
rstmods2fixed.tar.gz

The problem with these implementations is that unless the developer is 
committed to keeping them up to date
they die pretty quickly (e.g. the rst works with GRASS5 but not GRASS6).
So I have been begging everybody who tries to do parallel stuff for 
grass to do the parallelization
on top of the modules rather than within the modules so that they are 
minimally dependent on changes
within the modules. For example, v.surf.rst can be run efficiently by 
splitting region into smaller overlapping subregions
and sending each subregion to a different processor and then patch the 
results together. Same can be
done for r.mapcalc , r.slope.aspect and many other modules (there are 
some exceptions such as modules
that include flow routing). This may have its own problems but it is 
definitely more general and has much better
chance of surviving beyond one release cycle than writing a parallel 
version of a module.

I have plenty of large data sets (tens to hundreds of millions of 
points) but you need to get GRASS read them first.

Helena



On Nov 25, 2005, at 12:33 PM, Muzaffer Ayvaz wrote:

> Hi;
>  
> Some modules in GRASS, especially surface generation modules, takes 
> long times according to the our data and our parameters.I am trying to 
> write parallel versions of theese modules via MPI library, to be able 
> to run  GRASS in high performance parallel machines..
>  
> I have looked mailing list archives, and there is a people who is 
> trying to do also same thing. But this mail was in 1993. I couldnt 
> reach this person.
>  
> Now, I want to hear about your experiences. Does anybody try 
> samething? or Does anybody can give me knowledge about the compilation 
> of GRASS with this library (MPI), -mpcc must be used to compile-? Or 
> do you have large data sets for surface generation. 
>  
> Or which modules takes longs time in additon to the surface generation 
> modules,
>  I mean minutes, hours or more.
>  
> Tha! nk you for all
>  
> Your respectfully
>  
> Muzaffer Ayvaz
>
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Helena Mitasova
Dept. of Marine, Earth and Atm. Sciences
1125 Jordan Hall, NCSU Box 8208,
Raleigh NC 27695
http://skagit.meas.ncsu.edu/~helena/