[X4U] Tiger & 64-Bit Applications...

[Michael Winter]

On Apr 12, 2005, at 9:18 AM, revDAVE wrote:

> Tiger looks cool...
>
> http://www.apple.com/
>
> I was wondering exactly how much of the TIGER system is actually 
> running at
> 64-bits ...

AFAIK, all of it that needs to -which means not much.

I'm really struggling with the best way to explain this, but for most 
things 64 bit won't be done because its not necessary. For example, I 
don't know of any text encodings that require 64 bits. So there's no 
advantage to doubling (or more) the size of text files just to make 
them "64 bit". Same is true for the overwhelming majority of data a 
computer shuffles around. The same is true for the instructions. In 
fact using 64 bit values where 32 or fewer would do can slow things 
down (more bits to move around, fewer values fitting into L1/2/3 
cache...).

IMO 64 bit only does two things. 1) Increases the amount of memory that 
can be addressed and 2) makes it easier (and faster) to handle data 
that does require more than 32 bits. Tiger does all that when 
necessary.

> And what applications, if any, are running at 64-bits NOW ...
> Not sometime in the future.. Does anyone know?

I don't know, but not many will see any functional (or speed) advantage 
to being 64 bit. I'm guessing the only apps in the near term that will 
"go 64 bit" are the ones that need to access huge amounts of data 
(databases, scientific computing, maybe video...) or extensively use 
very large (or very small) numbers (scientific computing). i could be 
wrong, but I don't see an application like SimpleText ever needing to 
be 64 bit (and you'll never need more than 640 k/M/GB of memory).

So be wary of upgrades whose main new feature is "Now 64 bit 
everything".

-Mike