[mkgmap-dev] [PATCH v9] make maps in parallel

Mon May 18 13:08:20 BST 2009

On Mon, May 18, 2009 at 07:59:43AM -0400, Greg Troxel wrote:
> > How about this:
> >
> > 1 - with no option specified, the default number of jobs (aka threads)
> > is 1.
> >
> > 2 - specifying --max-jobs without a value will maximise the number of
> > jobs (i.e. create one thread per core).
> >
> > 3 - specifying --max-jobs=N will create N threads.
> >
> > Would that suit you?
> 
> That sounds great.  I think it would be reasonable to change the default
> to #2 after enough time has passed that we are really sure that there
> are no problems from running in parallel.
> 
> Perhaps there could be a regression test to compare the output from
> parallel and non-parallel runs.  I'm not sure if they are meant to be
> bit-for-bit identical, or if not if you can articulate the allowable
> differences.  This might require code to parse a .img into canonical
> form for semantic diffing, but that's probably a useful thing to have
> anyway.

+1.  Adding some regression testing and pretty-printing infrastructure
can never hurt.

I haven't tested these patches, because my laptop is only 1.5 GiB and
dual-core.  I'm not sure if two tiles of Finland would fit in the memory
at once.

	Marko