[Gdal-dev] improving gdal parallel build

[Alessandro Amici]

Andrey,

> > Parallel builds saves ~20% time on
> > uniprocessor system and much more time on multi CPU one. I have access to
> > the dual Xeon system and have ~2x compilation speed up.
>
> was it really 2x?
> i hardly belive it. there are still a lot of serial $(MAKE) calls into
> frmts and ogrsf_frmts, from what i can see on my UP some more work is
> needed before acheeving real linear scalability.

i updated the frmts and ogr/ogrsf_frmts directories to permit parallel access 
to sub-directories under 'make -j'.

this resulted on a peak of 300+ concurrent processes during the build (!!) and 
a much better parallelization overall... you might get very close to 2x on a 
dual-processor now.

BTW, nothing should have changed in the normal serial build.

cheers,
alessandro