Re: [gentoo-user] Status of Gentoo

[Alan McKinnon]

On Friday 14 March 2008, Mark Knecht wrote:
> It's an interesting question and one I've not tried to test. Does an
> AMD64 machine running a 32-bit or 64-bit install run faster or slower
> with one or the other.

Simple logic dictates that 32 and 64 apps will *generally* run at 
exactly the same speed, mostly because the amd64 arch is x86 with 64 
bit extensions. Unless your app is compiled to actually use the 64 bit 
features (you'd be surprised just how few are), 32 and 64 bit code 
tends to run at exactly the same speed using exactly the same opcodes 
at exactly the same clock rate.

For any app not using intensive 64 bit arithmetic (super-duper math/sci 
stuff and seriously intensive graphics are the only ones I can think of 
off-hand) it's hard to see a benefit for amd64 with current desktop 
memory loads.

The real benefit of amd64 becomes very obvious when you are dealing with 
apps that consume huge amounts of memory and 3G of addressable space 
for all apps just doesn't cut it. This is the problem amd64 was 
primarily designed to solve. When you have an app that does benefit 
from amd64 - like Sybase IQ just to pull a random selection from a 
hat :-) the difference is astounding.

Conventional desktops? Never seen a benefit yet on a normal desktop.

-- 
Alan McKinnon
alan dot mckinnon at gmail dot com

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