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

[Daniel Tourde]

Hello Bill, 

Thanks for your answer

> >    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?

With 'top'

> 
> >    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.

I think it's more that the port tree does not really like parallel processes...


> I'm still not convinced anything is wrong:
> *) Does dmesg show the second CPU starting?

Yes

> *) Does top show a column for CPU binding?  Are different processes bound
>    to different CPUs?

Yes

> *) 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.

No, it's a Dual Core

Daniel

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