[GRASS-user] Benchmarking Grass 4.3, 5.4, 6.0, 6.2 raster commands

[Roy Sanderson]

Hello Everyone

I've been trying to persuade our users to stop working with Grass 4.3 and
Grass 5.4 for some time now, and as I have to upgrade the OS on our
applications server have told them that they now have no choice.

However, a couple of users stated that they preferred to use Grass 4.3 as
it was faster, and for large tasks, more stable than the newer versions.  I
checked this on a map of 52,000 rows by 28,000 columns and commands like
r.mapcalc, r.clump, r.volume operated about 10x faster in Grass 4.3 than
the more recent versions.

This might simply arise from the age of the applications server OS (still
running RH7.3), or because I've mis-configured the newer versions of Grass.
 For example, I did not compile Grass 5 or 6 with large-file support
enabled, although the file sizes are only around 180Mb, but the speedy
performance of 4.3 vs 5.4, 6.0 and 6.2.1 surprised me.  Perhaps there's an
additional overhead associated with the introduction of nulls and
floating-points, which were major changes from 4.3 to 5.4.  However, the
performance difference is still present when working with integer maps.  As
I haven't benchmarked versions, and also because personally I only work
with Grass version 6, I hadn't spotted the differences until now.

Has anyone else noticed this issue?

Many thanks
Roy
----------------------------------------------------------------------------
-------
Roy Sanderson
Institute for Research on Environment and Sustainability
Devonshire Building
University of Newcastle
Newcastle upon Tyne
NE1 7RU
United Kingdom

Tel: +44 191 246 4835
Fax: +44 191 246 4999

http://www.ncl.ac.uk/environment/
r.a.sanderson at newcastle.ac.uk

----------------------------------------------------------------------------