[aklug] Re: 32 vs 64 bit

On Thu, Oct 21, 2010 at 05:16:42PM -0700, James Tweet wrote:
> I just got a laptop that has a 64-bit processor. On it I put the 64 bit version
> of Ubuntu and I want some info on peoples experiences.
>
> Questions:
> Are there any major differences between the 32 and 64 bit programs?
> Are there any gotchas that I should look out for?
> If I ran the 32-bit version of Ubuntu would it run slower, faster or the same?
> If I run 32-bit software on the 64-bit OS will it effect performance?
> Can I just recompile 32-bit code into 64-bit code?
> Any other advice or observations?
>
> Thanks
> James
>

This is not my special area of study. From what I understand, however, there should be measurable performance improvements by virtue of switching to a 64-bit OS, on account of the fact that the x86-64 extension provides access to eight additional cpu registers, which allows the code to keep more operational data off of the stack and on the faster registers.

Running 32-bit software on 64-bit OS should not have any negative impact on performance (aside from the inherent limitations of the 32-bit code) because x86-64 is fully backwards compatible with x86.

-- 
Christopher Howard
frigidcode.com
theologia.indicium.us
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