How to intrepret SIZE & RES on the TOP screen?

[Kelvin Yu]

Is there any correlation between SIZE & RES on the TOP screen? Can these tell if memory is leaking?

Thanks & regards,
Kelvin

[Pete Randall]

Kelvin,

From man top:

SIZE Total size of the process in kilobytes.
This includes text, data, and stack.

RES Resident size of the process in kilobytes.
The resident size information is, at best,
an approximate value.


Pete

[Bill McNAMARA_1 · Accepted solution]

-- finding mem leaks from cli

You can monitor for memory leaks from the command line. Assuming your process is running in background or as a daemon, identify the PID by:

# ps -ef | grep
# # Note the PID
# #
# # in what
# # follows.

# export UNIX95=1 # Turns on XPG4
# # behavior of 'ps'
# # (needed for -o
# # option to work)

Now display physical and virtual size of the process:

# ps -p -o sz,vsz,pid,state

If there is a memory leak, the values of sz (physical pages used) and vsz (virtual pages used) will gradually increase while the code executes.

[James R. Ferguson]

Hi Kelvin:

If you suspect memory leaks, one way to look for culprits is to watch for growth in the amount of memory consumed by a process:

# UNIX95= ps -e -o "user,vsz,pid,ppid,args" | awk 'NR>1' | sort -rnk2

Note the blank (space) character after the equal sign and before the 'ps' command.

Regards!

...JRF...

[Bill Douglass]

SIZE is the total virtual memory used by the process.

RES is the amount of that process's VM actually loaded into RAM.

If a process has a memory leak, the SIZE will continually increase.

See the man page for top for more details. Also look at ps as a way to get info about a process's memory usage.

Also check out process accounting (man 1m acct)