Core Duo - only one cpu being used

Eric Anderson anderson at
Fri May 5 13:10:50 UTC 2006

Attila Nagy wrote:
> Hello,
> On 05/05/06 06:44, Scott Long wrote:
>> CPU1 is being treated as a hyperthreading core instead of a real core, 
>> and is being disabled per our policy on Intel hyperthreading.  By 
>> 'disabled' I mean that it is started, but it is being excluded from
>> scheduling decisions, and thus is only running its idle proc.  It's
>> also handling any interrupts that come to it, such as timer and IPI
>> interrupts, so it's at 99% instead of 100% for the idle proc.  There
>> is nothing broken about the number you are seeing, your system is
>> just running under a scheduling policy that it should not be.
>> This should have been fixed a week or so ago by a commit to HEAD,
>> RELENG_6, and RELENG_6_1 by Colin Percival.  How old is kernel?
> Isn't this fixed by jkim's commit?
> I don't have any Core Duos here, but on a Xeon LV (Sossaman) with 
> CURRENT, everything is OK:
> BTW, just set machdep.hyperthreading_allowed=1 until the fix arrives.

I can confirm now that it is fixed in todays 6-STABLE.

Thanks everyone!


Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.

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