FreeBSD and "make -j# buildworld" usability

[Nikolas Britton]

On 10/13/06, Kent Stewart <kstewart at owt.com> wrote:
> On Friday 13 October 2006 07:31, Buki wrote:
> > Hi,
> >
> > I searched the archives and web a little but found many different
> > opinions on stability/usability of using make -j# with buildworld
> > (and buildkernel).
> >
> > So I am asking if it is a good idea to use make -j on production
> > boxes.
> >
>
> I tested buildworlds with different values for -j. On single processors,
> using a script that basically looked like
>
> time make -j? ...
>
> yielded fastest builds when I didn't specify a value for -j. On dual
> cpu's a value around -j8 yielded the fastest build.

That's odd, your results don't jive with this:
http://people.freebsd.org/~fsmp/SMP/akgraph-a/graph1.html

Although that report is quite old... My general rule of thumb for -j
is n +1, where n equals the total number of cpu cores. This is
generally enough to keep to processor(s) occupied without over
stressing the system. Maybe n * 2 is more appropriate, can you post
the results from your test?