freebsd-smp Digest, Vol 42, Issue 2
M. J. [Mike] O'Brien
mike at mobrien.com
Sun Jan 18 00:40:52 PST 2004
Hey Jonathon:
I don't think the modified GENERIC kernel config will do it for you. Try
this fir start at building a custom kernel or at leaast change your GENERIC
accordingly:
#########################################
machine i386
ident MULTICPU
maxusers 0
options SMP # Symmetric MultiProcessor Kernel
options APIC_IO # Symmetric (APIC) I/O
options IPFIREWALL
options IPDIVERT
####options HTT # HyperThreading Technology TURNED OFF!!
cpu I686_CPU
#########################################
best... Mike
Message: 1
Date: Fri, 16 Jan 2004 10:00:30 -0000
From: "Hall J D (ISeLS)" <jdhall at glam.ac.uk>
Subject: RE: machdep.hlt_logical_cpus missing in 4.9-Release?
To: 'John Baldwin' <jhb at FreeBSD.org>, "'freebsd-smp at freebsd.org'"
<freebsd-smp at freebsd.org>
Message-ID: <EF1C49A3F569D41186C900508B6DDC991359356B at ems3.glam.ac.uk>
Content-Type: text/plain; charset="iso-8859-1"
> -----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.
Thanks,
Jonathan
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