[arch-general] ?rch x86_64 and i686 performance comparison

[Sven-Hendrik Haase]

On 11.11.2009 17:44, Dieter Plaetinck wrote:
> On Wed, 11 Nov 2009 17:18:12 +0100
> Sven-Hendrik Haase <sh at lutzhaase.com> wrote:
>
>   
>> You will probably see the
>> opposite of what you saw in the VMs. Especially for video encoding,
>> x86_64 will be noticeably faster.
>>     
>
> why is that?
>
>   
I'm not a CPU expert and I got the figures by empirically testing just
what Sergey did, but in a real machine (Q6600). 64bit CPU have 64bit
registers which is what I suppose makes them work a lot faster for stuff
like video encoding, 3d rendering and encryption.
Somebody did a quick benchmark on this actually:
http://bingouv.blogspot.com/2008/08/desktop-linux-performance-comparison32.html
The results here would confirm it:
http://www.phoronix.com/scan.php?page=article&item=998&num=3
So it seems that x86_64 is usually a tad faster than i686 unless you
really try to make use of the architecture's advantages in which case
(according to wikipedia) it could become a lot faster.
Actually, why not just do some testing yourself and see what the results
are? 4-5 years ago, x86_64 computing was rather immature and lots of
optimizing assembly code for video encoders wasn't yet ported.

-- Sven-Hendrik