Benchmark 32bit vs 64bit

[Caterpillar]

Do you have some benchmarks between the 32bit version and the improvements of 64bit version?

[Thomas]

There should be none. 64bit is only really helpful in accessing more RAM.

[Caterpillar]

I believed that it could be good to have a 64bit version for complex calculus like physics.

[Tanshaydar]

I think it's just that game doesn't need to have 32-bit libraries installed on a 64-bit system.

[Caterpillar]

(09-08-2010 11:17 AM)Tanshaydar Wrote:  I think it's just that game doesn't need to have 32-bit libraries installed on a 64-bit system.

Yes but nobody wrote anything about 32bit libraries on a 64 bit system

[Urkle]

In reality you don't get any performance boosts with a 64bit binary.. Back at the dawn of the 386 processor (32-bit) there was a bigger improvement from 16bit to 32bit mainly because you got 32bit "moves". which when writing to video memory is a big improvement since a move take 1 clock cycle regardless of how much data you move (it's called move but really it's copy).

fast forward to nowdays and long before the 64bit desktop CPU was introduced by AMD we already had SSE, SSE2, 3DNOW, altavic (ppc), etc.. These all provided 64bit and even 128bit moves and fancier math functions as well.. Like being able to multiply two sets of numbers at the same time in one clock cycle..

So the ancillary benefit of 64bit (the bigger moves) had already been gained, so the only benefit is accessing more RAM.. which most programs don't need to address more than 4GB, and will work happily in 32bit mode.. And Yes a 32bit OS can access more than 4GB of ram. it's called PAE, just each application is limited to 4GB. (Microsoft imposed a desktop limit on 3 something GB because they most likely didn't want to mess with 3rd party driver issues. But there are ways of "fooling" windows into allowing you to access more)

[Caterpillar]

Ah ok, thanx for explaing this

[Gert]

Actually, in 64 bit mode the processor exposes more registers (general purpose and SSE), therefore the compiler can optimize better by keeping more temporal variables in registers. Hence, tasks that are executed mostly on the CPU may gain from running native 64bit as this article shows:
http://www.phoronix.com/scan.php?page=ar..._pae&num=1

However, the first benchmark in above article also shows that for computer games (that offload a lot of the work to the GPU), the choice of 64 bit over 32-bit doesn't play a big role and a difference may not be seen at all.