Running on only some cores

[Barney Cordoba]

--- On Tue, 1/20/09, Christoph Mallon <christoph.mallon at gmx.de> wrote:

> From: Christoph Mallon <christoph.mallon at gmx.de>
> Subject: Re: Running on only some cores
> To: barney_cordoba at yahoo.com
> Cc: freebsd-current at freebsd.org
> Date: Tuesday, January 20, 2009, 6:25 AM
> Barney Cordoba schrieb:
> > Can FreeBSD be configured to only run on N cores? So
> for example, if I have an 8 core system, can it be
> configured in loader.conf or through a simple hack to only
> run on 2 cores?
> > 
> > We're testing various configs, and its not
> terribly convenient to keep swapping out CPUs.
> 
> man 4 smp
> look for machdep.hlt_cpus

I've tried various settings for this but the system still launches all 4 cpus

machdep.hlt_cpus="0x7"
machdep.hlt_cpus="1"
machedp.hlt_cpus="0xC"

all result in 4 cpus being lauched. What is the trick?

Barney