Thin clients and centralized servers

Today in class I had the students log in to our server, galactus, via XDMCP. This basically turns their machines into thin clients, working off a central machine. Nearer to LTSP, though not quite just yet. I wanted to impress upon the students the idea of centralized management and all the upsides and downsides associated with it.

All told, the exercise went well. galactus, with a dual-core Intel processor and 2GB of RAM, managed to serve twenty or so students well enough with very little palpable load. The CPU utilization stayed steady at around 40% during idle moments. The processes barely registered a blip on top.

The only time galactus began to lag was when all the students opened up Firefox. Firefox consistently stayed as the top process. During those moments, CPU idle time went to zero, while the actual load was split between 80% user and 15% system. Fortunately, wait time was still close to zero; otherwise we would have seen thrashing.

Memory still had a few tens of megabytes left over, which fits the profile of other desktop systems that I've handled. Other parameters remained normal.

Given this performance, I would probably recommend a lighter web browser for a thin client setup.