[SATLUG] Ubuntu x86 vs x86_64 Performance

[Daniel J. Givens]

Phil Carinhas wrote:
>   64bit gives you greater capacity for file systems/sizes, larger memory & io
> paths, but it comes at a performance price: more memory will be allocated to
> accommodate this extra capacity, and io paths for apps take up more juice too.
> So its very common to see performance slowdown for 64bit systems. If your
> application is inherently 64bit though it could show a bit boost, but that
> isn't the everyday situation.
> 
>   We do system porting from 32 to 64, and its very important to do cpu, io, mem, 
> and network tuning to get the new systems to perform better than they did
> before out of the box. You do get more access to a larger memory address space
> and IO address space by far.
> 
>  So unless you really need that 64bit goodness, you might want to stick to 32 bit.
>  YMMV,

Wow! Thanks for the great information. I never would have realized that there
was more to it than compiling 64bit rather than 32. I guess I would have thought
that the compiler would handle that sort of optimization, but it makes sense for
languages like C and C++ where you do more with memory directly. One of the
biggest offenders of ungodly memory use was Sun's JVM. I guess they hadn't done
the optimization for the port that they could have.