Leopard 64bit - everyday advantage?

[MK2007]

64-bit will not help most desktop users. The advantage of 64-bit computing is for servers and the amount of memory they address. Having apps with upgraded bandwidth for science and engineering is a benefit to these users also.

The majority of Mac owners won't gain anything from 64-bit and their desktop machines. If you're a Power Mac user with 256 GB running scientific apps, then you will benefit. Everyone else running iLife on their iMac and MacBook Pro isn't going to experience any difference whatsoever.

 

[Fearless Leader]

No, you have double the processing power. On a 64-bit CPU all the internal data paths are double in width. If it takes 1 clock cycle to add two 32-bit registers (4 bytes) together on a 32-bit CPU, it will take 1 clock cycle to add two 64-bit registers (8 bytes) together on a 64-bit CPU. Double the amount of data processed.

ok but no. if i add 16+15 i get 31.
if i add 31+32 I get 63.

i didn't just do more work.

I can now add bigger numbers. go me!

and a 64 bit would take the same amount of time to add two 32bit numbers together as a 32bit.

 

[flopticalcube]

ok but no. if i add 16+15 i get 31.
if i add 31+32 I get 63.

i didn't just do more work.

I can now add bigger numbers. go me!

and a 64 bit would take the same amount of time to add two 32bit numbers together as a 32bit.

Add 5000000000 and 4000000000.

on a 32-bit machine that would need to be broken down into at least two separate 32-bit ops. When we talk of integer arithmetic its not just math on big numbers. Its operations on 8 bytes at a time rather than 4.

 

[Nutter]

ok but no. if i add 16+15 i get 31.
if i add 31+32 I get 63.

i didn't just do more work.

I can now add bigger numbers. go me!

Exactly. The point is that both 32-bit and 64-bit apps may need to do arithmetic on 64-bit data. 64-bit apps may be able to do it faster.

In reality this may not make much difference to most apps. The purpose of 64-bit is not speed, it's addressing more than 4 GB of memory.

Don't count on many apps going 64-bit for a while. That includes apps that ship with the system.

 

[flopticalcube]

Exactly. The point is that both 32-bit and 64-bit apps may need to do arithmetic on 64-bit data. 64-bit apps may be able to do it faster.

In reality this may not make much difference to most apps. The purpose of 64-bit is not speed, it's addressing more than 4 GB of memory.

Don't count on many apps going 64-bit for a while. That includes apps that ship with the system.

That's what we have been talking about. Its not just memory its large data operations as well.

 

[Fearless Leader]

Add 5000000000 and 4000000000.

on a 32-bit machine that would need to be broken down into at least two separate 32-bit ops. When we talk of integer arithmetic its not just math on big numbers. Its operations on 8 bytes at a time rather than 4.

That's what we have been talking about. Its not just memory its large data operations as well.

And now I play my trump card. The SIMD. Such as SSE, SSE2, SSE3, Velocity Engine. It closes the gap so much that it really doesn't improve it that much, and how many times will going over the 32bit range cause a slight performance hit. not very often.

 

[flopticalcube]

And now I play my trump card. The SIMD. Such as SSE, SSE2, SSE3, Velocity Engine. It closes the gap so much that it really doesn't improve it that much, and how many times will going over the 32bit range cause a slight performance hit. not very often.

Yep. programs that currently use SIMD will see only modest increases. Why? Because the SIMD registers are already 64-bit.

Two more examples: video games require large amounts of integer arithmetic to be done in the CPU. 64-bit games coupled with 64-bit video drivers will provide a noticeable improvemnt. Secondly, text or pattern searching will be sped up by searching 8 bytes at time for a text string or bit pattern rather than 4.