[K12OSN] CPU usage way up! What to do?

Brad Smith usernamenumber at gmail.com
Wed Sep 15 13:59:37 UTC 2004


Yes, CPU limits (and many other kinds of limit) can be specified in the file

/etc/security/limits.conf

The file has comments inside it that document usage and provide
examples, but bascially the syntax is:

who-to-limit         soft|hard          what-to-limit           how-much

Something I commonly do something like this this:

@students           hard         nproc          50

This limits the number of concurrent processes allowed to each member
of the 'students' group (the '@' denotes a group) to 50. I could have
used '*' instead of '@students' to have the limit apply to everyone. A
'hard' limit is a limit that cannot be changed. Users can use a
utility called 'ulimit' to alter their soft limits.

Anyway, this file lets you limits all kinds of stuff including the
number of minutes used by the CPU in fullfilling requests by the give
users' programs. However, I'm not sure the exact value you should use.
I assume this number is an average relative to the CPU use of others
over time and so builds up but then decreases over time. Otherwise
students would be locked out once they hit their limit. Unfortunately
I don't know the details of it.

Can someone else please clarify?

--Brad





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