64-bit

[Fawzi Mohamed]

On 2009-10-18 11:32:07 +0200, language_fan <foo at bar.com.invalid> said:

> Sat, 17 Oct 2009 22:56:44 -0400, Just Visiting thusly wrote:
> 
>> I won't deny that for certain people 32-bit systems are still perfectly
>> useful. Just my clients do not share this view for a series of good
>> reasons. Even their older systems tend to be 64-bit nowadays. Migration
>> towards 64-bit OSes is under way. There is still 32-bit compatibility if
>> needed. At the same time certain programs will perform drastically
>> better when compiled to 64-bit. Replacement thus can be postponed which
>> is usually the best way to keep CFOs happy.
> 
> 64-bit programs often also require larger CPU caches to work efficiently,
> more disk space (larger binaries), and finally larger memory consumption.
> 32-bit x86 + PAE still works until you have more than 64 GB of RAM or
> processes larger than 2 or 3 GB. So, in desktop use 32-bit feels like the
> best way to go unless 64-bit algorithms are provably more efficient in
> the chosen task.

on x86 the 64 bit extension added registers, that makes it faster, even 
if as you correctly point out a priori just using 64 bit pointers is 
just a drawback unless you have lot of memory.

Anyway I also need 64 bit (computational chemistry, speed and memory 
hungry), and to that the only thing that I can say is D1 works very 
well with 64 bit.

Fawzi