[uClinux-dev] parallel compiles

[David McCullough]

Jivin Mike Frysinger lays it down ...
> On Thursday 07 February 2008, David McCullough wrote:
> > > On Wednesday 06 February 2008, David McCullough wrote:
> > > > > is there a reason for forcing -j1 in sub-packages ?  we've dropped
> > > > > the -j1 in {lib,user}/Makefile for the DIRS target and generally had
> > > > > great success.  you can really feel the difference on an 8 or 16 proc
> > > > > system. i also replaced the -j1 for the _only targets with
> > > > > -j$(HOST_NCPU).
> > > >
> > > > Interesting result,  do you have an measured build times with and
> > > > without the change ?  It would be nice to know,  and if the gains
> > > > justify the fixing of any potentially broken sub dirs :-)
> > >
> > > just doing a simple `time make AnalogDevices/BF537-STAMP_default` here
> > > ... - with NON_SMP_BUILD set: ~8min
> > >  - without NON_SMP_BUILD set (and the -j1 pieces removed): ~1.5min
> > > pretty consistent here ... +/-10seconds
> >
> > I was hoping for the "with -j1" and "without -j1" numbers,
> > comparing against NON_SMP_BUILD=1 is not really fair ;-)
> 
> how is it not fair ?  the NON_SMP_BUILD var forces -j1 ...

NON_SMP_BUILD=1 means there are no parallel builds at all, everything is
done sequentially,  and while useful for finding build errors etc,  it
is a lot slower than the default partially-paralleled uClinux-dist build
process.

The default in the  uClinux-dist is to build multiple lib/user directories
at the same time,  but each directory is built single threaded (-j1).

> i didnt feel like 
> locally modifying the Makefiles to get the same result

patch -R ;-)

Cheers,
Davidm

-- 
David McCullough,  david_mccullough at securecomputing.com,   Ph:+61 734352815
Secure Computing - SnapGear  http://www.uCdot.org http://www.cyberguard.com