Memory/cpu quoatas for users

[Mike Moran <mm@ee.ed.ac.uk>]

Hi. I am looking for a way to limit the amount of memory and cpu used by
the apache
daemon, since the web machine is very resource-limited. I know I can
reduce the
maximum number of servers, but that doesn't limit usage by each server.
Perhaps a
default "nice" level would also help. How do you set the default nice
for a user?

The thing is, would either of these stop something like a while(true)
loop, which allocated memory? I've been making some changes to the
apache daemon mod_perl setup recently and I end up being locked out
because something swamps out the system. I get `half-connects' where,
for instance, ssh/telnet connects but then just sits there until it
times out. This sounds exactly like a thrashing problem. I had a top
running and kswapd
seemed to be the last thing I saw before it hung.

Maybe this is a kernel level thing? Is there something like a
high-watermark process killer that I could use, ie something which
started rampaging around when memory usage crept above a certain level?

Note that I think the problem will probably settle out once I've stopped
making so many
changes to the apache setup but, for now, it is a pain to have to ask
for my machine to be
powercycled. Regardless, it would be nice to know I have a safety net,
just in case.

Thanks,

--
Mike