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[mkgmap-dev] Memory limits for mkgmap and splitter

From Chris Miller chris.miller at kbcfp.com on Wed Aug 5 22:16:18 BST 2009

Exactly, uncompressing is pretty hard on the CPU so ideally we'd want to 
make as few passes as possible. There are other factors too though, eg I'm 
thinking about doing the decompression on one thread and the parsing/splitting 
on another thread if there is more than one core available. I haven't yet 
tried to profile the splitter but once I've got rid of most of the low-hanging 
fruit I'll explore options like that a bit further. At this stage it's still 
hard to know whether additional passes are going to be better or slower than 
paging some of the data to disk.


> Just an thought from reading the thread:
> Multiple parsing runs with an bz2 zipped file could do worse to the
> performance. It would mean multiple decompressing of the input files.
> And in my experience decompressing bz2 costs a lot of resources.
> (In my case I'm directly using the osm.bz2 files from geofabrik as
> input.)
> Regards,
> Johann

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