[K12OSN] 8 GB RAM on 32-bit Edubuntu with AMD 64 processors

[James P. Kinney III]

On Mon, 2007-11-26 at 12:37 -0800, Robert Arkiletian wrote:
> On 11/26/07, James P. Kinney III <jkinney at localnetsolutions.com> wrote:
> > The PAE will be a nightmare for the heavily shared setup of LTSP. In
> > short, the system will thrash doing high page swaps to access RAM. If
> > all processes under current request are spread over multiple pages, the
> > performance will be beyond horrible.
> >
> > If you _must_ use 32-bit on a AMD-64 bit machine, put no more than 4GB
> > RAM in the system. Even then you may loose 512MB (depends on mainboard
> > chipset). I'm not sure if the Nvidia chips will loose RAM as all of my
> > servers using those have 8GB or higher and 64-bit OS.
> 
> I have 4GB of ram. My kernel is using PAE so I see all 4GB. Wondering
> if performance hit (some say 6-8%)  is only for that extra 512MB or
> for the entire 4GB?

I'm reasonably sure that the PAE swapping occurs once the in use memory
exceeds 3765 MB (4 GB-331MB). So until then it's not an issue. For a
running LTSP server....
> 
> Also wondering how does one disable PAE? Running 4.2.3EL the 2.6.9.x
> kernel has PAE enabled by default. Is there a kernel rpm I can
> download or will I have to recompile the kernel?

I have not seen a boot parameter listed except associated with XEN.
pae=(0|1).  I don't know if it's valid so boot at your own risk :)
> 
> -- 
> Robert Arkiletian
> Eric Hamber Secondary, Vancouver, Canada
> Fl_TeacherTool http://www3.telus.net/public/robark/Fl_TeacherTool/
> C++ GUI tutorial http://www3.telus.net/public/robark/
> 
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-- 
James P. Kinney III          
CEO & Director of Engineering 
Local Net Solutions,LLC        
770-493-8244                    
http://www.localnetsolutions.com

GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
<jkinney at localnetsolutions.com>
Fingerprint = 3C9E 6366 54FC A3FE BA4D 0659 6190 ADC3 829C 6CA7
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