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Date:      Wed, 18 May 2005 18:11:32 -0700
From:      "David O'Brien" <obrien@freebsd.org>
To:        Astrodog <astrodog@gmail.com>
Cc:        freebsd-amd64@freebsd.org
Subject:   Re: FreeBSD on dual core Opterons - stupid buildworld test
Message-ID:  <20050519011132.GB64608@dragon.NUXI.org>
In-Reply-To: <2fd864e05051811442152fa@mail.gmail.com>
References:  <428B6FC1.3000907@fsn.hu> <1116437340.69035.0.camel@hood.oook.cz> <20050518180521.GB9719@odin.ac.hmc.edu> <200505181441.39457.jkim@niksun.com> <2fd864e05051811442152fa@mail.gmail.com>

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On Wed, May 18, 2005 at 11:44:13AM -0700, Astrodog wrote:
> > > > > http://people.fsn.hu/~bra/bl45p/dmesg.boot
> > > > >  Hyperthreading: 2 logical CPUs
> > > >
> > > > So dual-core Opterons report into system as Hyperthreading?
> > > > Uncool.
> > >
> > > What the AMD reps said at a session I attended last year is that
> > > they report as supporting hyper threading, but set another bit to
> > > say that they are actually real cores.  We probably need to find
> > > out what that bit is.
..
> 
> Opteron reports Hyperthreading, because it tries to take advantage of
> the licencing benifit. Keep in mind, HT P4s are counted as a single
> CPU for the most part, in a licence. Opteron may not. By acting as
> though its a HT processor, it gets that same benifit.

Partical truth.  AMD also sets the HTT bit so that legacy OS's (ie, those
released before AMD dual-core) will take some advantage of the 2nd
core(s).

-- 
-- David  (obrien@FreeBSD.org)



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