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

Bill Moran wmoran at
Wed Feb 7 21:44:44 UTC 2007

In response to "Daniel Tourde" <daniel.tourde at>:
>    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.

Also, there are places in the build process where it's only possible to
run one process at a time, so you can't just take a single snapshot of
it, you have to watch it over time.

>    How can I correct th   Thanks in advance,

I'm still not convinced anything is wrong:
*) Does dmesg show the second CPU starting?
*) Does top show a column for CPU binding?  Are different processes bound
   to different CPUs?
*) Are these hyperthreaded CPUs?  If so, is hyperthreading enabled?  HT is
   disabled by default on FreeBSD, and overall usage will never go above
   50% if HT is off.

Bill Moran
Collaborative Fusion Inc.

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