Build an erlang computer (was:Computers are fast)

[Vlad Dumitrescu XX (LN/EAB)]

Hi,

> Question: Is there a simple program to make main memory 
> totally unavailable in my linux system? - I'd like to boot 
> the system saying "use only 100K of memory" or "use only 200K 
> or memory"
> (I currently have 512K) so I can measure the effect of 
> different memory sizes on performance.

There usually is a mem=XXXM boot parameter for the kernel. I don't know
if it works to restrict it, or is it just for cases where the default
doen't recognize all installed memory.

Otherwise, it is also possible to restrict memory usage per user, using
the PAM module.

You can control the per-user limits using the resource-limits PAM module
and /etc/pam.d/limits.conf. For example, limits for group users might
look like this: 

                @users     hard  core    0
                @users     hard  nproc   50
                @users     hard  rss     5000

This says to prohibit the creation of core files, restrict the number of
processes to 50, and restrict memory usage per user to 5M. 

Regards,
Vlad