I'm having difficulty with memory usage on my VPS (CentOS) running PHP sites.
Until now I have been able to change things and reboot to try to analyze and fix things before the memory usage climbs again, but now when I type reboot it can't even do that.
How can I reboot my VPS machine and get out of this catch-22?

5 minutes later: now memory is almost totally maxed out, what could be causing this and how can I begin to fix it when the response time when logged in via SSH is so slow?
