topic Re: memory utilization in Operating System - Linux

memory utilization

khilari — Thu, 12 Jul 2007 09:30:11 GMT

Hi guys, i wanted to know as if how do you know if the memory is being utilized to its fullest. Sometimes Insight manager takes away some memory. So, how first of all i know how much is the memory and then how do i know if it is being used to the fullest.
Thanks.
p.s: it is a DL380-g5 Server.

Re: memory utilization

Steven E. Protter — Thu, 12 Jul 2007 09:39:27 GMT

Shalom,

You can use lsof or top to see the top memory users.

Note:
output of the free command will show unused memory allocated as buffer cache. I've seen that annoy people, but that is the dafault behavior of Red Hat distributions.

SEP

Re: memory utilization

Vitaly Karasik_1 — Thu, 12 Jul 2007 09:59:10 GMT

I suggest you to start from this reading:

http://forums.gentoo.org/viewtopic.php?t=175419 Linux Memory Management or 'Why is there no free RAM?'

http://www.redhat.com/magazine/001nov04/features/vm/ Understanding Virtual Memory

Re: memory utilization

JanN — Thu, 12 Jul 2007 10:15:08 GMT

A nice graphical tool to see where memory has gone - and if processes are growing/shrinking could be gmemusage.

This is an old IRIX tool - which has been cloned:

http://oss.sgi.com/projects/gmemusage/

Re: memory utilization

skt_skt — Fri, 13 Jul 2007 17:50:42 GMT

cat /proc/meminfo to find physicla memory

"free -mt" output; add both free and cached whihc is equal to total free memory

Total under Mem:is total physical memory too

# free -mt
total used free shared buffers cached
Mem: 3768 3571 196 0 459 2791
-/+ buffers/cache: 321 3447
Swap: 2047 71 1975
Total: 5815 3643 2172

"UNIX95= ps -eo pid,user,sz,vsz,args|sort -nbk3" to list the processes interms of memory.sz represents the mem usage and vsz is the swap usage.

UNIX95= ps -eo pid,user,pcpu,args|sort -nbk3
where pcpu valus is the cpu usage.