machdep.hlt_logical_cpus missing in 4.9-Release?

Hall J D (ISeLS) jdhall at
Fri Jan 16 02:03:07 PST 2004

> -----Original Message-----
> From: John Baldwin
> Sent: 15 January 2004 18:06
> On Thursday 15 January 2004 05:48 am, Hall J D (ISeLS) wrote:
> > I've recently installed 4.9-Release (from the ISOs) on a 
> twin Xeon system
> > and compiled a generic SMP kernel (GENERIC with SMP and 
> APIC_IO enabled).
> >
> > The problem I'm having is the system is using the logical 
> HyperThreading
> > CPUs even though I don't want it to.
> >
> > The errata for 4.9-Release says that the logical CPUs are 
> prevented from
> > executing user processes by default, they are not on my 
> system. It also
> > says you can control this behaviour by change the value of the
> > machdep.hlt_logical_cpus sysctl(8) variable. My sysctl 
> doesn't seem to know
> > about this variable.
> >
> Well, you can do 'sysctl machdep.hlt_cpus=10 to get the same 
> effect to turn 
> off CPU's 1and 3.  I am not sure why you are not getting the 
> sysctls.  Are 
> you familiar with C?

I am not familiar with C, but I'm happy to check what I can if you point me
in the right direction.

The machine I was using for these tests has now gone into production so I'll
have to build another before I can test the machdep.hlt_cpus option. I'll do
that in the next few days and let you know how it goes.



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