[K12OSN] Poor performance woes

Jomegat jomegat at jomegat.com
Tue Sep 20 19:18:08 UTC 2011

I have a K12Linux setup based on EL6-64.  The TC's are ancient i686's 
with 256M RAM and 10/100 nics.  The TS has a gigE NIC, and between the 
TS & TCs is a managed switch with 2 gigE ports and 24 10/100 ports.  The 
TS is connected via one of the gigE's.

We have a student who is having real performance problems when he loads 
a page.  I went in today to be there while he was experiencing woe, and 
ran the system monitor applet.

When he loads the web page - with no flash in it that I can find - the 
network maxes out at 12MiB/sec, and it takes an eternity for the page to 
load.  He reports that sometimes this particular page will cause the TC 
to crash (black screen with text followed by login screen), but he was 
not able to reproduce that while I was there.  I suspect there is some 
user error involved in the crash scenario, but it will be difficult to 

I had tried running firefox as a local app last month, but the school 
needs flash, and it requires 512M.  Performance on these TC's was 
substantially worse when running FF as a local app, so I backed off of that.

The page he was trying to load is password protected, but I had him 
ctrl-U while he had it open, and save the source to a file which I can 
share if need be.  It is filled with javascript, but I'm not sure that's 
the culprit (though it seems the most likely suspect).  I found no .flv, 
FLV, .swf, or .SWF in the file anywhere.

As an experiment, I connected a monitor, keybd, and mouse directly to 
the server and had him login there.  The page loads just fine that way. 
  That might be a possible solution, but for some reason, the display is 
incredibly blurry.  If I make that permanent, I'd have to run some cable 
through the wall (they're pinched in the door right now, and barely reach).

Before they called me in to look at this, he had been bringing his mom's 
laptop to school so he could do his work (it's an online course).  If it 
crashes while he is taking a quiz, he loses a test attempt or gets a bad 
grade, so this has to be reliable.

His mom is on the school board, and she is pushing the school to abandon 
LTSP in favor of a Windows solution.  They think that if they install 
some flavor of windows on the TC's they will get better performance, but 
I believe they won't, as flash will need 512M no matter the OS.  I think 
they will need all new PC's if they go that route.

I am on the cusp of losing my network to Windows, at which point I will 
resign my post as unpaid volunteer sysadmin, so if I sound a little 
desperate, now you know why.

Any help here would be greatly appreciated.

Jim Thomas            Principal Applications Engineer  Bittware, Inc
jthomas at bittware.com  http://www.bittware.com    (603) 226-0404 x536
The problem with the future is that it keeps turning into the present - 

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