Switching from 64 bit to 32 bit version

[James Gray]

On 20/07/2008, at 3:40 PM, Leonard Bussey wrote:I have an AMD64 and  
was happy with the 64 bit version, but I could not use Adobe Flash  
with Firefox.
> I now use the 32 bit version.  Everything seems to work just fine  
> and I
> do not see much of a performance difference.


Unless you are trying to use massive amounts of RAM, or do  
calculations on very large numbers (double precision floating points  
etc), then you will see practically NO performance difference between  
32 and 64 bit environments.  You will, however, run into many  
compatibility problems when trying to work with 32bit-only libraries  
and programs (win32 codecs and flash player...I'm looking at you!) in  
a pure 64bit environment.  You can, as others have suggested, run  
32bit code on AMD64/EM64T processors by virtue of the fact they  
support both 32 and 64bit code.  However, the methods for achieving  
this are, IMHO, ugly and inelegant.

FWIW, when I was at university I did some research on this and as it  
turned out, there were "measurable" differences between 32 and 64 bit  
for our test suite (single precision floating points, <4GB RAM...ie,  
what a "normal" user would do) however, the differences were far less  
than anything you could subjectively notice.  The difference when  
working with large numbers and large memory address space (8GB for  
32/64 comparisons...at the time, we couldn't boot a 32bit kernel with  
more than that) was dramatic.  When working with our crypto test suit  
on 4GB RAM, the 32 vs 64 bit was a lot clearer cut in favour of  
64bit...but again, was due to the very large numbers required in crypto.

I'll see if I can dig up the results, but don't hold your breath - it  
was while, and several computers, ago....I've noticed vast tracts of  
my university days missing from my hard drives (both literally and  
figuratively).

Cheers,

James
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