[nzlug] 32bit vs 64bit speed/performance

[Daniel Pittman]

Jack Pivac <email at delphinus.co.nz> writes:

> What with a new Ubuntu round the corner I'm going to do a clean
> install and wondering 32bit or 64bit?

For a desktop?  Unless you plan to put more than 3GB[1] of memory in it
then you want a 32-bit Ubuntu on the system.

> Have you found much performance increase by going with 64bit? 

No, and generally no one will.  The performance gain from all those
extra registers is generally eaten up by the fact that your CPU cache
just got cut in half and your programs spread out over all those extra
cache lines to accommodate those larger pointers.

> (And just normal day to day stuff, no weird compiling/mathematical
> equations etc)

All the extra benefits such as assuming instruction set extensions, etc,
don't really show up outside this space.  Well, except in Emacs, which
takes advantage of the larger integers to enable larger buffers.

For day to day work you don't see much performance difference between
the two modes.

> Any major problems with 64bit?

Yes.  Binary only software is routinely available only in 32-bit
versions, so you end up needing complex shims (nspluginwrapper) or to
abandon various 32-bit code.  On the desktop this is often a pain.

Regards,
        Daniel

All that said I will be using 64-bit on my new desktop around the time
Gutsy is released and living with the pain.

Footnotes: 
[1]  or anything up to 3.8GB with the right hardware.

-- 
Daniel Pittman <daniel at cybersource.com.au>           Phone: 03 9621 2377
Level 4, 10 Queen St, Melbourne             Web: http://www.cyber.com.au
Cybersource: Australia's Leading Linux and Open Source Solutions Company