On Sun, Dec 28, 2008 at 1:18 PM, Markus Neteler <[email protected]> wrote: > Hi, > > I am planning to calculate energy maps based on a high res > DEM (458890698 cells, FCELL type). I'll use a multi-core > computer with several GB of RAM in a cluster environment. > > How should I calculate the "numpartitions"? What is the expected > memory demand? I have to tell the job scheduler how much > memory I need for each process - I want to calculate daily > energy maps, so submit each day to a node of the cluster.
Here the answer from the author: On Tue, Dec 30, 2008 at 9:34 PM, <[email protected]> wrote: > Ciao Markus, > > I had a look at the source code. Most of the memory is used to store the > rasters (or part of the rasters if you use numpartitions>1). > > How much depends on the options you use. I have made a little table of the > input and output options and the amount of memory the use per pixel. The > addition (if) means that it is optional, so you may have from 1 to 6 output > rasters. The output rasters are not partitioned, only the input rasters: > > Output rasters > > incidout (if) float > insol_time (if) float > beam_rad (if) float > diff_rad (if) float > refl_rad (if) float > glob_rad (if) float > > Input rasters. Size should be divided by numpartitions: > > elevation float > slopein (if) float > aspin (if) float > linkein float > albedo (if) float > latin (if) float > longin (if) float > coefbh float > coefdh float > horizon (if) numhorizonstep bytes > > A float is 4 bytes, so you can calculate the memory usage yourself. > Horizon values are stored in the program as 1-byte integers to save memory. > > I just tried one example, and the expected memory used was 252000 KB while > the actual memory used (according to "ps aux") is 259000KB. I guess the > rest is pointers, code and smaller arrays. > > Hope this helps. > > Thomas I'll add that to the manual in condensed form. Markus _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
