SMP detection

[Skylar Thompson]

Jordi Carrillo wrote:
> I've read that SMP should be disabled for performance issues (I did
> not know
> that before installing freebsd). I have a P4 3GHz with hyperthreading
> technology. I have the SMP-GENERIC kernel and it only launches one
> cpu. So,
> I've decided to disable SMP from BIOS. Is that ok?, knowing that I have a
> Smp enabled kernel? or should I install one without smp? If so, is
> there a
> way to install one already precompiled?
> Thanks in advance
>
I believe that HTT was disabled in FreeBSD per security report
FreeBSD-SA-05:09.htt
(http://security.freebsd.org/advisories/FreeBSD-SA-05:09.htt.asc). If
you want to enable, I believe you can set the loader.conf option
machdep.hlt_logical_cpus to 2.

Having SMP enabled on a uniprocessor box shouldn't give you any
stability problems, but SMP does use a different locking mechanism that
can affect performance. You will probably get slightly better
performance if you run with an SMP-disabled kernel.

-- 
-- Skylar Thompson (skylar at cs.earlham.edu)
-- http://www.cs.earlham.edu/~skylar/


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