[K12OSN] Re: tuxpaint and others running slow

[Dan Kegel]

On 10/21/05, Justin Paulsen <paulsenj at frederic.k12.wi.us> wrote:
> I am having a similar problem, as current I've only experienced this
> with TuxType2 and VMware (not a surprise there).  I'm fine with a few
> users but at about 14 or so its unusable.
>
> Server:     1x AMD Opteron 252 1.8GHz (Dual proc capable)
>                 2x 160GB 7200 RPM SATA drives in RAID 1
>                 Dual Gbit NIC
>                 4GB RAM
>
> Switch:     24pt Gbit (D-Link)

Let's figure out what the bottleneck is.  (This goes for anyone who's having
performance problems on an LTSP server.)

Run just one of the two apps, say TuxType2, on all workstations at once.
Verify that the slowdown happens.

Once you have the slowdown going, then let's look at the server:
run 'top' on the server.  Grab the output with the mouse
and post it here so we can see what's up.  It'll look something like this:

top - 22:24:23 up 49 min,  2 users,  load average: 0.10, 0.09, 0.07
Tasks:  86 total,   1 running,  84 sleeping,   0 stopped,   1 zombie
Cpu(s):  2.6% us,  0.3% sy,  0.0% ni, 96.7% id,  0.0% wa,  0.3% hi,  0.0% si
Mem:    515304k total,   309264k used,   206040k free,    15984k buffers
Swap:  1048568k total,        0k used,  1048568k free,   178104k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 3221 root      15   0  100m  17m  88m S  2.0  3.4   0:49.79 X
 3572 dank      15   0 37536  12m  21m S  0.3  2.4   0:03.33 gnome-terminal
...
That'll tell us a lot.

And let's look at the network:
use ping to examine the health of the network connecting the server to
the workstations, e.g. run "ping -c100 -A client1" on the server,
and post the statistics it prints at the end.  It'll look like this:

100 packets transmitted, 100 received, 0% packet loss, time 19899ms
rtt min/avg/max/mdev = 0.493/0.512/0.553/0.015 ms, pipe 2, ipg/ewma
201.002/0.513 ms

Any packet loss indicates trouble with the network.

I'm looking forward to seeing your results.