[mkgmap-dev] [PATCH v1] make maps in parallel

Mon May 11 12:21:25 BST 2009

OK, let it not be said that I don't listen to others!

The attached patch provides support for making maps in parallel. By
default, the behaviour is the same as before but if you specify
--num-threads=N where N is greater than 1, it will process N maps at
the same time and then combine the results (if required). Don't forget
to increase the heap size appropriately.

A quick test on the big box shows good speedup - specifying
--num-threads=4 and 2GB VM size. I  was seeing better than 380%
utilisation with 8 cores in use.

I suspect the performance limitation here will be VM size and memory
system bandwidth.

BTW - I don't think num-threads is actually the best name for the
option, so please suggest alternatives.

Cheers,

Mark
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