[mkgmap-dev] Performance with large files

Sun Mar 19 11:06:31 GMT 2017

How is mkgmap expected to behave when input files grow in size? Is a 
linear inrease in calculation time - i.e. O(n) - expected, or an 
increase beyond linearity?
E.g. when I create a map with routable lines for bicycle, mkgmap takes 
some 30 minutes for Germany alone (3 GB pbf file resulting in 850 MB img 
file), but more than  2 hours for Germany and some neighboring countries 
(7 GB o5m file, resulting 1.4 GB img).
Are there many calculations at O(n^2) or beyond in mkgmap, or is this 
due to other factors, e.g. memory limitation?
Notes:
mkgmap is called by
%JAVA% -Xmx6800M -ea -jar %MKGMAP% ....
on 64bit Win 7;
swapping to disc does not occur.
But I am more interested in a general rule than in some hints for 
improving the performance in this concrete case. E.g. how I could 
estimate the duration if I add some further countries...
Thanks for your hints.