[Ubuntu-US-PA] 32 bit vs. k64 bit for Linux

Lee Sharp leesharp at hal-pc.org
Tue Apr 24 15:31:45 UTC 2012

On 04/24/2012 07:15 AM, SilverTip257 wrote:
> @Lee:  I find that hard to believe x64 will be slower than x86 with
> <4GB of memory.  I can't think of a reason why that might be the case.
>   I'd like to know for certain - could you share the benchmarks or
> article with us?
> For anyone following this thread:  PAE compared to 32-bit and 64-bit>
> http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae&num=1
> and the slight performance hit of PAE.

I am not talking about pae here, (Never tried it) but there is an easy 
way to show this.  Make a virtual box, or your VM of choice.  Install 
Ubuntu 12.04 32 bit in one, and 64 bit in the other.  Bring up a shell 
and type "free -m" as soon as you log in.  Look at memory and the size 
of the swap file.  Do this several times to get an average. Swap files 
are slower than memory...

That said, some of the 64 bit kernels are better optimized for the 
modern CPUs.  (Or some of the 32bit kernel still assume you are using 
CPUs with no extensions)  So you get benchmarks like these that say the 
opposite of what I am saying. 


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