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

[James P. Kinney III]

On Tue, 2007-11-27 at 15:10 -0500, Jim Kronebusch wrote:
> On Mon, 26 Nov 2007 13:46:55 -0500 (EST), Tom Wolfe wrote
> > .... So Jim what do you have to say about this?? From what I recall you 
> > report good performance with PAE/LTSP and 16 GB RAM with 100+ users.
> > 
> > Regards,
> > Tom Wolfe
> 
> Sorry for the slow reply.
> 
> I server 108 terminals from my single LTSP server running Edubuntu 7.04 and the
> linux-image-server kernel version 2.6.20.16.28.1.  I have seen 75 concurrent users all
> running Firefox with Adobe Flash and OpenOffice and have seen max processor usage at
> less than 25% and RAM at I believe 6GB or so.  Whether or not PAE takes a performance
> hit over 64-bit, I'm sure that it true, how much, nobody seems to know for sure.  But I
> assure my setup is running great, and the screen resolutions are at 1280x1024.  Sound
> works great.  I did try all the tricks with K12LTSP based LTSP, all the 32-bit firefox
> tricks or using nspluginwrapper to tie 64-bit firefox with 32-bit supporting apps worked
> flawlessly.  However under Ubuntu this was not the case.  The only way I was able to get
> working sound in flash 9 on the thin clients under Firefox was with 32-bit OS and 32-bit
> apps, nothing else worked.  I had all tricks for libflashsupport, nspluginwrapper, you
> name it, no sound in flash 9.  This is why I went the way of PAE to support my RAM and
> processors with the linux-image-server kernel.  Everything worked, and all RAM available.
> 
> Now, it isn't like I'm running this many users on a dual PIII box with 16GB RAM.  I'm
> running a Dual Quad Core 2.66Ghz Xeon box (a total of eight 2.66Ghz cores).  I also run
> 6 300GB 3Gbps SAS drives in RAID 10 and 6 GB NICs teamed in alb for network throughput.
>  And 16GB RAM.  So if there is a performance hit, this might be why I don't see it.

Plus, the controller chip may artificially allocate a semi-dedicated
chunk of RAM to each core further masking the PAE swap effects. With
Opteron systems since each CPU is it's own RAM manager, the PAE issue is
further diluted. So far what I've seen is the PAE effect is most
pronounced where you'd expect it - on a single 32-bit CPU system with
large RAM installed.
> 
> So to enable PAE in your 32-bit Edubuntu server, "sudo apt-get install
> linux-image-server", when finished reboot and be sure it grabs your new kernel.  Then
> verify all processors and RAM show up.  If the performance isn't good enough, then scrap
> flash and go 64-bit.  Hopefully as the new local app support develops this will become a
> non-issue.  I plan on moving Firefox, flash, java and any other possible 32-bit apps
> local in the future, then run a strict 64-bit server.
> 
> Hope this helps.
> 
> Jim
> 
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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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