[vox-tech] 32 vs. 64

[Mike Simons]

On Thu, Oct 20, 2005 at 04:03:54PM -0700, ALLO (Alfredo Lopez De Leon) wrote:
> I just got a new Poweredge 1850 (Dual Xeon 3.8 GHz, 2 MB RAM, SCSI) and
> I am planning to install on it Fedora Core 4.  The question is: Should I
> use the i386 version or the x86_EM64T?
[...]
> I am wondering if I will run into trouble with my applications.  Most of
> them if not ALL are 32-bit.  

You should install the x86-64 version.  The 64-bit compiled code should 
run faster so even if all your apps are 32-bit ... at least you'll have
a 64-bit kernel.

I've not checked how FC4 does it, but most 64-bit linux flavors install
"32-compat" libraries also... some default to 64 bit in /lib and use
/lib32, others default to 32 bit and provide a /lib64.


> Is anybody aware of any potential problems? Is there an associated cost
> of running 32-bit applications on 64-bit machines?

On the x86 chip there I've not heard of any significant performance hit
running 32 bit code when in 64 bit mode... the same code compiled in 
64-bit mode often run faster because there are twice as many registers.