[lug] Memory problem

[D. Stimits]

Justin wrote:
> 
> I'm running into a memory issue on my main server machine. I have never had
> this problem before and it seemed to start within the last 2 weeks. Using
> procinfo I am seeing the memory usage gradually increasing until it reaches
> the max of 128megs. Last week I started killing off process's randomly to see
> if that free'd memory but no luck. I tried restarting all my main server apps
> including apache, postfix, identd, syslog, inetd, and some others. The memory
> usage still showed the same, but when doing a ps aux none of the process's
> seemed to be hogging any memory. I ended up shutting down and booting back up
> to clear the memory problem. After the reboot the mem usage, according to
> procinfo, was about 50megs. After my users had started up all their stuff
> again the memory was up to about 90megs, which is normal. I ran my
> counterstrike server for a while saturday night, which consumes about 28megs,
> then shut it down later on. The memory dropped back down to around 90megs
> after that but has been increasing daily for no particular reason. It's now at
> about 122megs of the max 128, and the only thing I've done since the weekend
> was update my BIND to P7. Any way to trouble shoot this or any ideas of what
> might be going on? The box is Redhat 6.1 (updated) w/ kernel 2.2.15. Thanks in
> advance for any help.
> 
> Justin
> 

Sometimes, depending on how you are measuring the memory use, the
meassurements can be deceptive. Released memory will sometimes not be
simply released, but will instead end up cached. And if you are running
an X server, your video card memory can be measured as part of the
system ram...if it has 32 megs and the system 128, you could see up to
160 megs in use. One thing I'd suggest is using a tool that
distinguishes between just ram used, and cache. Try xosview if you can.

If it turns out that you do have memory being used up, it's possible
that one of your apps has a memory leak. Sometimes a restart mechanism
to a daemon does not actually kill the app, but simply tells it to
re-read its init files; if this is the case, memory won't go down after
a restart. Try a full stop and stop.