[plug] LTSP server load

[Craig Ringer]

>>23217 craig     15   0 44732  43M 35528 S     0.0  2.1   0:02 soffice.bin
>>23453 guest     15   0 44480  43M 35352 S     0.0  2.1   0:02 soffice.bin
>>
>>but 'free -m' only shows a 9mb increase at each new instance.
> 
> Shared memory - much of it libraries.

I suspected as much, but I thought the RSS excluded libs. Oh well, 
thanks for the tip. What this /means/ in our setup is that the first 
OO.o instance uses somewhere between 43 and 9 mb of memory, and each 
following instance uses 9mb. Woohoo :-)

50mb/user would be overkill, with 20mb being a more realistic value. 
Hmm... 100 users should be entirely do-able. There are only 30 people in 
the business :-) so I think the server will do us fine for /quite/ some 
time...

>>Real world effect: adding a client may as well not have happened for all 
>>the difference it makes to the server. I wouldn't be surprised to be 
>>able to support 50 - 100 clients on this machine, though memory might 
>>become an issue then (depending on what the "real" memory use of our 
>>environment is).
> 
> I think your single network connection will saturate; unless you've
> got a gigabit (server has a gigabit interface if it's a recent x235)
> switch on the back of it.

Gigabit all the way :-)

Intel PCI-X Gigabit Copper NIC, connected to one of two gigabit ports in 
our core switch. If I ever needed to, I could drop in another NIC and 
trunk it to ~2 gig. I don't need the second gigabit port in the switch 
for uplink because it has proper shared-backplane stackability. 
Honestly, though, the traffic is SFA, mostly X11 cares about latency not 
throughput. This is not some icky RFB implementation. I see bursts when 
users are loading or scrolling big images, but otherwise little traffic.

> xfce makes a big difference in memory footprint.

Certainly compared to GNOME or KDE, which are IMHO too complex, fragile, 
slow and hard to manage. I was originally using IceWM but XFCE took the 
cake in useability and general "nice" value. IceWM sure is small though 
- p'haps 2mb?

The users really only need a simple environment, and XFCE does the job 
brilliantly. I did have to throw out its file manager for excessive 
crapness, and I've replaced it with ROX-Filer 2.0 with great results. 
Nautilus also works, but is overkill. ROX could, IMHO, do with some UI 
work but is overall very good.

>>Oh... did I mention? The vast majority of that load average score is 
>>user screensavers ;-)
> 
> Goes to show how little work people actually do with computers. :-)

And how disgustingly wasteful full-power desktops are in networked 
business environments. I like the balance provided by thin clients - 
they do their own rendering, but all the real system resources and user 
data are on the server side. If it dies - throw it out and put in a new 
one. I've got a stack of spares, and it takes me about a minute to 
configure a new client anyway. Installing the new machine is as simple 
as plugging it in. I like this :-)

Craig Ringer