[nzlug] machine pre loaded with linux

[Daniel Lawson]

> In other words: yes, a 128MB machine could *comfortably* run an X server
> with plenty of space left over for local applications, let alone only
> running them remotely.
>
> 64MB would require a little swapping -- all my code is mapped in,
> without swap in use -- but should be quite comfortable.
>   

In theory, this looks great. In practice it's not so peachy because of
the behaviour of certain components.

I used to work[1] in the WAND group at Waikato Uni, and we deployed
linux based thin clients with 128 MB of ram, and a debian woody (2.4
kernel, xfree86 3.something) with an NFSroot system.  No swap. They ran
perfectly fine, unless you used mozilla or firefox quite a lot. The
pixmap allocation would increase, and eventually the kernel would
overcommit memory, and X (being the requesting application), would die.

The initial solution was "close firefox, mozilla and thunderbird every
night" or "log out every night", but that got tedious, and these were
dedicated per-user machines, not general purpose ones. After messing
round with network backed swap (via NFS + patches or via NBD), we put
another 64 or 128 MB of ram in them.

Later on, they were upgraded to Debian Sarge with a 2.6 kernel and
whichever version of Xorg sarge comes with. This had much nicer
behaviour when a memory allocation error occured - the X server catches
the error and passes it on to the requesting application, thus killing
it instead. Much nicer.

However, this still means that, even on systems with 256MB of ram, your
app would still die when it overcommits. This isn't just the mozilla
suite of programs either. Try to load a large PDF with embedded images?
Or how about a satellite photo? Or do any gimp work with large images?
Forget it.

My point is: 128 MB *should* be enough. After all, these are thin client
units and are designed to do this. The HP ones ship X natively and often
have local copies of firefox on them if you don't want to require
terminal services of some sort.   If you log out regularly or don't want
to do any heavy lifting in terms of graphics viewing, you'll be fine.
But I wouldn't guarantee you'll never have an application fail due to
lack of memory.



[1] I no longer work at WAND, but I'm pretty sure they still run the
same system. Newer hardware than before, and maybe a newer base distro.