I have a 256MB RAM VDS with Debian Lenny, Apache2, MySQL, mod_php (and some PHP websites). In this configuration VDS have about 35MB RAM left. So, I installed mod_wsgi (in daemon mode) and some very simple Django site (just for testing, it's one model and Django admin). After that only 25MB left. It's OK, but after visiting Django admin apache spawns about 6 more processes (and in total I have 9 processes: 1 under root, 7 under www-data and one for mod_wsgi). So, now I have only 6MB left. And after each visit Apache eats more memory and, finally, no memory left and I need to reboot server.
What can I do or read? Of cause, it's possible to extends VDS' RAM, but it's last resort.