[CentOS] Adding RAM

Ross Walker rswwalker at gmail.com
Sat Dec 6 16:44:45 UTC 2008

On Dec 5, 2008, at 7:18 PM, Rainer Duffner <rainer at ultra-secure.de>  

> Am 06.12.2008 um 01:02 schrieb Ignacio Vazquez-Abrams:
>> On Fri, 2008-12-05 at 23:57 +0000, Michael Holmes wrote:
>>> 2008/12/5 Matt <lm7812 at gmail.com>:
>>>> I have a server running Centos 4.7 32bit.  Will moving from 4Gig of
>>>> RAM to 8Gig do any good?  Since its 32bit I assume it will only be
>>>> able to address the first 4Gig not?
>>> As long as you are using a SMP kernel you can use up to 64GB of RAM
>>> (though each proccess can only address 4GB of this). So if you can
>>> find any trace of  "SMP" in the uname (grep is your friend) then it
>>> should work fine.
>> PAE, not SMP.
> He should be able to replace the kernel via rpm -e and rpm -i
> That said, I doubt he'll actually see a benefit.
> PAE is slow.
> If you want to see a real performance-gain, install 5.2 x86-64.

He'll see a benefit. PAE slowdown is humanly unnoticeable for short- 
term transactions, it's difference is in high nano seconds or low  
micro seconds.

All 5.0 kernels are PAE by default.

So are WinXP_SP2/Win2K3/Vista/Win2k8 and Mac OS X kernels.

Only go 64-bit if it's completely necessary.


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