[K12OSN] lbussd CPU usage?

[Jim McQuillan]

Shawn,

lbussd really shouldn't be using any measurable amount of cpu when 
things are idle.

Once lbussd starts up and gets initialized, it goes into a loop where 
it's waiting on data coming over the network from the workstation.  It's 
using a select() call, so it shouldn't be using any resources at all.

It has a timeout on the select call of 5 seconds.  That's just so that
every 5 seconds it can check to see if the users session is still alive.
Even then, it's doing such a small amount of work, that I don't think 
you'd see it show up in top or any other measurement tool.

If lbussd is chewing up cpu time, like you've mentioned, then I'd 
suspect that there's traffic on the network, coming from the client.

lbussd uses port 9202.  I'd try running tcpdump and watch that port, to 
see if there's some traffic.  It would be perfectly normal to see some 
packets when you plug a device into the client, or when you access data 
on a floppy or cdrom.  Other than that, there shouldn't be any traffic 
at all.

Pick one of the clients to study, and do this:

     tcpdump -i ethX host wsXXX and port 9202

Substitute the correct value for ethX and wsXXX.

Then, sit back and watch the screen.  see if there's activity.

If there is, and you can't decipher what is going on, then try tcpdump 
again, but this time capture the packets, so we can look at them with 
wireshark.

     tcpdump -i ethX -s0 -w /tmp/tcpdump.out host wsXXX and port 9202


Let that run for several minutes, then kill it with Ctrl-C.  Then,
send me the /tmp/tcpdump.out file (as an attachment).

Jim McQuillan
jam at Ltsp.org



Shawn Powers wrote:
> I recently installed 2 K12LTSP servers, and I'm using xfce for the 
> desktop manager.  I've noticed the CPUs (dual xeon 3.2ghz) are 
> constantly at 100% usage, and the culprit seems to be an lbussd process 
> for every user consistantly using 5-6% of the CPU.  Is this normal?  
> I've never seen it before, but before I was using IceWM, so perhaps 
> that's the difference.
> 
> Anyway, it's pretty easy to see why my clients are currently slow, if 
> every user is using 5-6% of the CPU just idling...  Might I configure 
> something differently, or is that just "the norm?"
> 
> Thanks,
> -Shawn Powers
> 
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