Disabling HyperThreading?

Jack L. xxjack12xx at gmail.com
Wed May 5 16:12:51 UTC 2010


sysctl machdep.hyperthreading_allowed=0 will disable it.

On Mon, Apr 26, 2010 at 6:48 AM, John Baldwin <jhb at freebsd.org> wrote:
> On Monday 26 April 2010 5:59:19 am oklahoma wrote:
>> Hubert Tournier wrote:
>> >
>> > I forgot to specify that the system is a remote dedicated server, for
> which
>> > i have no physical access.
>> >
>> > I could rent a virtual KVM in order to try to access its BIOS settings,
> but
>> > i'm not sure this would work.
>> >
>> > Any other software solution?
>> if the server is dedicated entirely to you, ask your colo support to
>> disable it for you.
>> other thing i find was
>>
>> machdep.hlt_cpus
>>
>> is suppose to tell the scheduler that there is extra cores but not to use
> them.
>> try to enable and see with top is there app that use logical cores.
>
> You can manually disable any CPU (except for the boot CPU), via
> 'hint.lapic.X.disabled=1' in loader.conf.  You can find the APIC IDs to use in
> place of 'X' in dmesg.
>
> --
> John Baldwin
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