Intel Core Duo. SMP kernel but still only 50% load while using make on ports...

[Kris Kennaway]

On Wed, Feb 07, 2007 at 04:44:42PM -0500, Bill Moran wrote:
> In response to "Daniel Tourde" <daniel.tourde at spray.se>:
> > 
> >    Hello,
> >    I have at my disposal an Inspiron 9400 with an Intel Core    FreeBSD 6.2
> > is installed and rebuilt to fit the processor. The kerne   l is in SMP mode.
> >    I noticed something strange: When I compile using ma   in the ports
> > tree, I only have 50% load. CPU1 is used at   CPU0 is idle...
> 
> How do you know this?
> 
> >    I tried make -j2 but it did not work,   Any idea?
> 
> -j2 does not guarantee that you'll use both CPUs.  It's entirely possible
> that the IO is slow enough that both of the processes are waiting on disk
> and only able to push the overall system usage to 50%.  Try make -j99.

make -j in the ports tree is not going to compile the source in
parallel, it is going to try and run the port targets in parallel (but
they cannot be parallelized so nothing special will happen).  In
theory it might work on some ports to pass in MAKE_ARGS=-j2, but a
huge number of ports cannot be safely be compiled in parallel
(i.e. the build will fail) because their developers have not added
support for this.

Kris
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