parallel builds revisited

[[LoN]Kamikaze]

Benjamin Lutz wrote:
> On Thursday 12 April 2007 11:06, Garrett Cooper wrote:
>> I dunno how you want to approach this, but gmake does recommend 2
>> jobs be run in parallel for HTT enabled chips, and 3 or 4 jobs for a
>> dual core machines.
>> -Garrett
> 
> So far the approach is one job per CPU. I'll do some benchmarks lateron 
> to determine wether it really helps to run more jobs. For the KDE 
> ports, my gut feeling is that the improvement would be negligible. I'll 
> have to evaluate non-C++ ports like gnome-*, where the compilation time 
> per file is shorter.

I find the benefit especially big with Gecko based ports like Firefox or
Thunderbird.
 
> Of course, to make proper use of distcc, at least #cores + 1 jobs are 
> required. I'll keep that in mind.

The recommendation of the Distcc developers is 2 jobs per core, as long as
the machines contain sufficient memory.

My personal experience says that it's rarely possible to divide a Makefile
into more than 6 threads.