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Re: Resource limit question



On Sat, Mar 24, 2001 at 05:18:24PM -0800, Karsten M. Self wrote:
> 
> Um.  I feel stupid asking this, but what resource limits *do* work, and

per user process limits work (though pam_limits and/or ssh is broken
in that you must set it higher then the number of root owned processes
for logins to work) core size limits work, cpu utilization works (any
process taking more consecutive time then allowed is killed) and
virtual memory works.  im not sure if anything else works as i don't
know of a useful test for each.  rss i know for sure is totally
ignored by the kernel.  

> how can user resource limits be imposed at the system level?  I've been

pam_limits and /etc/security/limits.conf (latter being the config for
the former)

> looking at the bash man pages -- there's no more specific resource
> utilization interface, is there?

bash's ulimit command just uses the same resource limit calls any
other program will use.  some shells just don't provide a command to
set the limits, but they are subject to limits set by thier parent
(pam_limits).  limits are [supposed to be] enforced by the kernel.  

> My preference would be to be able to limit memory utilization.  *Some*
> form of CPU throttle could also be useful under some circumstances.

ulimit -v is all you got then AFAICT.  this is the `as' limit in
/etc/security/limits.conf.  note that when a process runs into this
limit it will just die horribly (killed, segfault etc).  as for cpu
throttle, you can set the number of seconds a process can take at a
given time, so say you set a limit of 60 seconds, your shell will be
fine but a password cracker will be killed after 60 seconds (since its
constantly sucking the cpu) 

/me wishes there was more documentation on resource limits, and that
they actually worked under linux properly.  

-- 
Ethan Benson
http://www.alaska.net/~erbenson/

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