On a hyperthreaded system, top and gnome system monitor only report one processor

Josh Carroll josh.carroll at gmail.com
Thu Aug 25 07:35:41 GMT 2005


Speaking of which, is hyperthreading in 6.0 with ULE to the point
where it actually increases performance for multi-threaded processes
or parallel compilations (make -j N)? Obviously this is situation
dependent. I guess the better question is whether HT is able to
provide a performance increase in 6.0 like it purports to do?

I've heard that it's not quite "there yet", so I'm cautious about
enabled SMP support and HT support on a P4-HT system.

Josh


On 8/24/05, Colin Percival <cperciva at freebsd.org> wrote:
> Justin R. Smith wrote:
> > FreeBSD jsmith.org 6.0-BETA3 FreeBSD 6.0-BETA3 #0: Tue Aug 23 08:04:37
> > EDT 2005     jsmith at jsmith.org:/usr/obj/usr/src/sys/MYKERNEL  i386
> >
> > Top lists all process as being run by processor 0
> >
> > The gnome system monitor lists only processor 0 as well (under gentoo
> > linux it shows two).
> 
> Hyperthreading is disabled by default for security reasons.  If you want
> to enable it (which is generally safe on single-user systems), you should
> add the following line to /boot/loader.conf :
> 
> machdep.hyperthreading_allowed=1
> 
> Colin Percival
> FreeBSD Security Officer
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