[mythtv-users] i386 vs x86_64 Fedora

Miroslav Suchý miroslav at suchy.cz
Thu May 15 20:43:58 UTC 2008


dcw napsal(a):
> I am in the process of getting the components for a new computer for Mythtv. 
> On a x86_64 computer is there an significant advantage of using a x86_64 
> version of Fedora over a i386 version of Fedora?

Memory:
i386 - can use up to 3.5GB (more with some tricks which limit speed)
x86_64 - can use "unlimited" memory
*** Probably not affect on MythTV deployment

Instruction set:
i386 - your code is compiled for i686 instruction set and you do not use 
full power of you CPU
x86_64 - there is no enhancement to x86_64 instruction set yet. 
Therefore you will use all instruction your CPU know.
***  Several percent of speed gain on x86_64

Size of registers:
i386 - 32 bit size
x86_64 - 64 bit size, you can storage here 2 times more data.
*** Several percent of speed gain on x86_64. This item give you most of 
the boost.

Applications:
i386 - all aplication works
x86_64 - some closed source aplication are not ported to this arch 
(Flash, win32 codecs). You can usually make it work (nspluginwrapper) 
but it take some work.

My recomendation:
if you are geek or you need every percent of speed - use x86_64 arch.
if you are just user and not power user - use i386 arch of Fedora and 
put there x86_64 linux kernel. This way your application will run on 
i386 instruction set and all will work without problem. But kernel will 
utilize power of x86_64 CPU.

Miroslav Suchy
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