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

Sven-Hendrik Haase sh at lutzhaase.com
Wed Nov 11 11:18:12 EST 2009

Virtual machine performance is in no hell comparable to real machine
performance, not even for comparing between each other. Current VM
implementations generally run a lot faster on i686 guests because that's
what they have been optimized for mainly. I always found my x86_64 VMs
to be slower than i686 so this would go in hand with your own
observations. If you want to make a serious comparison, set up two fresh
chroots at least. Better yet, set up two partitions and do the tests
using a native kernel as well. You will probably see the opposite of
what you saw in the VMs. Especially for video encoding, x86_64 will be
noticeably faster.

-- Sven-Hendrik

On 11.11.2009 17:11, Sergey Manucharian wrote:
> Hi folks,
> The similar question most probably has been discussed many times, but I
> really cannot find a clear answer. There are some obvious thinks like
> 64-bit addressing, but how about math calculations performance?
> I've set up two identical virtual machines in vbox - one with Arch
> x86_64 and another with Arch i686. I ran mencoder in both over the same
> video and got the following figures:
>   x86_64: 43 sec
>   i686:   34 sec
> which make x86_64 not so impressive ;)
> Some time ago I read an article at AMD web site, they suggested using
> their math libs for writing programs instead of standard ones. In such
> a case a program with complex math involved can performs much better
> (personally I haven't tried).
> I'm just curious about other people's opinions on this subject.
> Cheers,
> Sergey

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