[Wylug-discuss] Linux on Intel 64-Bit Xeon

[John Hodrien]

On Thu, 23 Jun 2005, Jason Lander wrote:

>>    1. Which Intel 64-bit architecture is a 'Dual 64-Bit Xeon'?
>
> I think this is the `EMT' - the 32-bit chip with 64-bit bells and
> whistles.

> It is their `anything AMD can do, we can quickly emulate if it looks like
> a good idea' model.

Indeed EM64T is the intel pretender for the AMD64 extensions.  It's really not
as good, and the HPC crowd seem to be distinctly unimpressed with its large
memory performance.  But that's not to say the chips are poor performers.

It's the joys of their cross licensing deal that either of them can use
gubbins like this.

>>    2. Does the label '64-Bit Xeon' apply to both, and if so, how do you
>>    tell the difference?
>
> I think Xeon == 32 bit. The purely 64-bit one is the Itanium.

Yes.  Xeon is IA32 that can include EM64T extensions for half-arsed 64bit
support.  IA64 is Itanium 1 or 2 which is properly 64bit and can run IA32 code
with the ia32emul layer under linux (which works passably).

Typically the distro level distinction is made thus:

i386
x86_64 (either AMD or Intel 64bit x86 compatibles)
ia64 (Itanium 1/2).

>>    3. What is the state of kernel and distro support for either
>>    architecture?
>>
>>    4. Assuming that there is fairly good distro support for the kit on
>>    offer (Dell suggest RH/SuSE), is the CPU performance reasonable for
>>    the price?
>>
>
> Not sure about the 1850 but there is a dual Xeon Dell Poweredge *1800*
> here running Debian sarge. The Debian kernel is 2.6.8-10-em64t-p4-smp.

Did you notice any performance difference running that with x86_64 on the
PE1800?  We've got a 4Gb Dual Xeon 3.6 Dell box running with Fedora 3 x86_64.
I'm not completely sold with FC3's ability to cope nicely with the package
management of a split architecture system though (pointing some of the blame
in yum's direction).

jh

-- 
"History teaches us that men and nations behave wisely once they have exhaused
all other alternatives."                             -- Abba Eban