maximum of CPUs

Cagle, John (ISS-Houston) john.cagle at
Mon Jul 14 13:06:30 PDT 2003

If you enable hyperthreading on an 8-way server, you'll end up with 16 logical processors (and a *whole bunch* of APIC's) -- a scenario that is not comprehended by FreeBSD.  In other words, there needs to be some more engineering done on FreeBSD to support more than 8 processors (AFAICT).

> -----Original Message-----
> From: Attila Nagy [mailto:bra at] 
> Sent: Monday, July 14, 2003 2:59 PM
> To: Cagle, John (ISS-Houston)
> Cc: Patrik Veselík; freebsd-smp at
> Subject: Re: maximum of CPUs
> Cagle, John (ISS-Houston) wrote:
> > I think that 8 CPUs is pretty much the limit for FreeBSD.
>  > We have FreeBSD 5.1 running on an 8-way HP ProLiant DL740 and HP
>  > ProLiant DL760.  (That's 8 processors *without* using 
> hyperthreading.)
> Just out of curiosity: what happens if you enable hyperthreading?

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