can make -j be used for ports?

[John]

On 15/03/2011 22:35, Eitan Adler wrote:
> No, this is incorrect. The MAKE_JOBS_NUMBER and MAKE_JOBS_SAFE is used
> internally when building a single port. When the OP is asking if he
> can manually specify -j on the command line which would end up
> building multiple ports in parallel. This can not be done (primarily
> because there is no locking done on ports)

Actually, he has it partially right, at least in the idea I was trying
to convey. I'll explain again, because maybe I wasn't coherent enough
previously:

I have an amd x2 6000+ with 8GB RAM. It's a wonderful fast desktop. Not
the fastest, but it's fast enough for me. What I want to do is this:

1. If I can speed things up, with *ports* as I have a dual cpu, I want
to maybe run j2 or j3. I seek clarification which is logically best,
because some literature says jn, others jn+1 where n is number of cores.

kern.smp.cpus: 2 on my machine. Is there benefit setting this to 3,4,5?

I want to know if there is perhaps a conf file or sysctl where I can
specify this *for ports only.* - if not I'm happy to specify on the
command line. It's just that the manual is a tad unclear about this.

2. Where I was being unclear I think is when I was talking about
building the system. I have seen in the literature that -jn when
installing world Breaks Things. This isn't an issue as I run RELEASE and
so only either apply patches or make the system, so easy to specify,
where I can, -j3 except in make installkernel and make installworld.

thanks,
-- 
John <lists at reiteration.net>