[mkgmap-dev] splitter r325: improved split algo and new option

Wed May 7 10:36:26 BST 2014

Hi Felix,

well, nowadays splitter performance mostly depends on I/O if you use o5m format
for input and output and give enough heap. 

Reg. mkgmap performance improvements: yes, that's what I expected.
In short, the branch improved the evaluation of tags and the creation of the NOD file.

Gerd

Date: Wed, 7 May 2014 11:29:10 +0200
From: extremecarver at gmail.com
To: mkgmap-dev at lists.mkgmap.org.uk
Subject: Re: [mkgmap-dev] splitter r325: improved split algo and new option

    Well - I'll update all my maps on Thursday again, to recheck. Maybe
    it has to do with increasing-maxnodes? Though I thought the higher
    the max-nodes, the faster...

    And I only meant splitter. I upgraded mkgmap at the same time (now
    integrating performance branch changes) - so mkgmap by itself got
    faster (though it depends on the country - seems like well mapped
    countries profit a lot more (e.g. Austria like 30% time off), than
    countries where few continue commands will be in action cause their
    mapping is basic like Asia).

    I'm not using any pre-split files or cached files of any sort
    either...

    On 07.05.2014 06:49, Gerd Petermann
      wrote:

      Hi Felix,

        reg. speed: I can't reproduce that. I compared a split of
        Germany, 

        both versions (r321 and r325) are more or less running the same
        time.

        (I've executed both programs two times to make sure that disk
        caches 

        are not causing big differences)

        Or did you mean the combination of splitter + mkgmap to process
        e.g. Asia?

        Gerd

          Date: Tue, 6 May 2014 18:22:00 +0200

          From: extremecarver at gmail.com

          To: mkgmap-dev at lists.mkgmap.org.uk

          Subject: Re: [mkgmap-dev] splitter r325: improved split algo
          and new option

          Seems to be much better now. I don't think I can increase the
          max-nodes value though, but for most maps the new algo creates
          less tiles for the same max-nodes value (e.g. Austria from 43
          down to 35 for me, with the smallest tile now around 5MB
          instead of 2.8, and the biggest 12MB instead of 11MB, for Asia
          I simultaneously increased max-nodes from 800k to 900k- so I'm
          down from 624 tiles to 493.... and size from 970KB-16MB to now
          ). So it still seems to depend on the country, but it's
          already a lot better...

          It's a bit slower (about 10% more time) 

          On 06.05.2014 13:56, Gerd
            Petermann wrote:

            Hi all,

              I've applied num-tiles-v1.patch  and improved the split
              algo, see

              http://gis.19327.n5.nabble.com/mkgmap-ToDo-list-tp5803388p5805165.html

              It is now less likely that splitter creates tiles with a
              low number of 

              nodes, it is more likely that all tiles have nearly  the
              same number of nodes,

              and typically you will see fewer tiles.

              Maybe this also means that you can increase the max-nodes
              value.

              I hope this also reduces the need for complex interactions
              between 

              spltter and mkgmap.

              Gerd

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          -- 
keep on biking and discovering new trails

Felix
openmtbmap.org & www.velomap.org

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    -- 
keep on biking and discovering new trails

Felix
openmtbmap.org & www.velomap.org

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