Is there any way to setup Debian to prioritize any or specific root's activity before every other? For instance, several times per year something gets wrong (usually man's fault by overstressing apache/mysql) and system gets unresponsive under heavy load like 200 (8-core cpu).

I know there are limits for php scripts to run then kill, but that's not the way because this limit has to be at least 45 minutes long. The problem is, until I'm able to login via SSH and let apache/mysql restart under this server stress, it nearly hits these 45 minutes anyway.

Also hardware restart causing usually to run fsck at boot time on all harddrives since it's usually pretty long the box haven't been restarted. I was told it's really not good idea disabling fsck but then again, it takes more then hour to complete.

What is the fastest way to restart apache/mysql? Is there any way to give ssh users or root user higher priority so the logging in and completing these restarts (rather stops though) commands wouldn't take so long?

One comes to my mind.. use NICE for apache/mysql but no way. I can't risk limiting those two vital apps 24/7 or could I? I'm a little bit scared if any other system process wouldn't slow the pages down too much. Any backup process, swap (if any) etc. There is pretty heavy PHP framework with 20k visits a day, so it needs every hw/sw resource available. I can't throttle it the whole time, just in certain points when system gets unresponsive, so I could maintain it.