[mkgmap-dev] Performance with large files

Sun Mar 19 19:39:40 GMT 2017

OK, quite surprising numbers.
I'll see if I can reproduce them and if there is something wrong.
It seems you are using splitter with keep-complete=false?
It would be great if you could post the areas.list from splitter and
the options for both programs.

Gerd
________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Bernhard Hiller <bhil at gmx.de>
Gesendet: Sonntag, 19. März 2017 19:46:32
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] Performance with large files

Eventually I updated Java and tried the latest version of mkgmap 3847
(and also splitter 580).
The extracts were retrieved from Geofabrik on Saturday 18.
Germany: 2.93 GB
plus additional countries: 5.62 GB (incl. Germany) which were combined
to a 7.57 GB o5m file.
splitter: Germany 14 minutes - Central Europe 20 minutes
mkgmap: Germany 30 minutes - Central Europe 133 minutes
While splitter performed better than O(n) (more like O(sqrt(n))),
mkgmap performed worse than O(n^2).

Am 19.03.2017 um 12:06 schrieb Bernhard Hiller:
> 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.
>

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