[oe] PARALLEL_MAKE

[Mike (mwester)]

Ulf Samuelsson wrote:
> Is there any activity to make this more useful?
> Just managed to install a Core i7 machine, which speeded
> up my Buildroot build from about 4 hours to less than 1 hour.
> (There was an error in the build right at the end,
> so it could have been downto 40 minutes or so)
> Building the cross compiler took 10 minutes with "make -j 16"
> compared to 1-2 hours on a P4 @ 3GHz.
> 
> Openembedded does not seem to use PARALLEL_MAKE extensively.
> I have the frequency meter activated for all 8 CPUs in the Core i7,
> and most of the time the CPUs seems to idle at 1.6 GHz,
> with one CPU (or rarely 2) are running at the full 2.67 GHz.
> 
> Last time I built OE on a P4@ 3 GHz it took ~40 hours 
> for the SAM9263, so some speedup would be nice.
> Maybe we should make an effort?
> 
> Best Regards
> Ulf Samuelsson

I build often with PARALLEL_MAKE set, and have been rather regularly
flushing out packages that break due to improper Makefile dependencies.
 The latest offender is thttpd; I'll be committing the fix to force that
to always run without PARALLEL_MAKE shortly.

My new quad-core does a dandy job of keeping all four cores busy almost
100% of the time -- but you need to specify BB_NUMBER_THREADS to get it
to do that.  Ever since somebody fixed the fetcher problem, that works
very, very nicely indeed.

-Mike (mwester)