32 bit or 64 bit

[leoalvesmachado]

Hi everyone...

I'm working in a project that uses QT and I want to get the best performance possible. My software code should be platform independent, so I can run it in any OS.
Today, I am compiling the project only for 32 bit machines, forcing the OS of 64 bit machines to translate the compiled instructions.

My question is: This approach I've chosen (compile only in 32 bit) impacts the performance negatively if I run it in a 64 bit machine? Is so, would it be slower than a 32 bit machine (completely equivalent machine, but 32 bit), or it would have the same speed?


Thanks in advance for your attention

[Zlatomir]

...impacts the performance negatively if I run it in a 64 bit machine?...

The impact, if any, won't be semnificative.

I use 64 bit OS from 2006 for my primary PC (Windows Vista, at first and now 7), and i havent seen no "slow-down" of any 32 bit software. I don't know about Linux because i only used 32 bit versions.
But this depends on what the software does, there are "tasks" that denefit from 64 bit processor/OS.

[Talei]

In my programs I didn't see any performance difference between WinXP 32 and Win7 64b, also Debian 32 vs Xubuntu 64bit.
In general performance difference in 32 vs 64 bit architecture are practically 0 (I didn't see a program that would actually be significant faster due to usage of 64bit). I use 3DSmax for heavy duty tasks like rey-trace, AO generation, and so one... no difference in these tasks or render time, and probably same goes for 99% of application.

PS. I don;t know how situation looks on actual 64bit architecture like i.e. IA64