Hyperthreading Issues (on Athlon64?)

John Baldwin jhb at freebsd.org
Thu Oct 12 07:08:35 PDT 2006


On Tuesday 10 October 2006 19:15, JoaoBR wrote:
> On Tuesday 10 October 2006 16:43, John Baldwin wrote:
> > On Tuesday 10 October 2006 14:55, JoaoBR wrote:
> > > On Tuesday 10 October 2006 15:11, Brooks Davis wrote:
> > > > > My dmesg does not have the line about "Hyperthreading: 2 logical
> > > > > CPUs", though.  But I had been pretty sure the Athlon64 chips didn't
> > > > > have any hyperthreading support.  Why is the HTT there?
> > >
> > > HTT is NOT hyperthreading, HT is and HT does not exist on AMD64
> >
> > Err, no.  The HTT there stands for HyperThreading Technology.
> 
> you say it right: "stands for" in this case
> 
> But I think it "is" the other way round, in terms of abreviation:
> 
> HTT = Hyper Transport Technology
> HT = Hyper Threading (Technology)

I don't think this really bothers anyone.

> Even if this is certainly ok for whom knows it,  then an AMD X2 is definitly 
> not a hyperthreaded processor but has 2 cores as well as Intel's newer Core 
> Duo, so HTT for an AMD X2 would be wrong (my opinion again)

You didn't read anything I said earlier.  When dual-core came out, to make it
easier for OS's to detect it (probably Windows), AMD made a dual-core CPU
look just like an Intel CPU with 2 hyperthreads including using the CPUID
HT flag in cpuid that _Intel_ had reserved.  Even ports/misc/cpuid calls the
flag HT.  Sheesh.

-- 
John Baldwin


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