14.8. Monitoring CPU User and Idle Times

Problem

The previous recipe gives a useful snapshot of CPU activity over time, but you would like to see separate rather than aggregate values, such as idle time and user processes, or system and user processes, or perhaps one of these alone.

Solution

Try adding this to mrtg.cfg:

	# monitor CPU user and idle loads
	#
	Target[xena2.cpu]: ssCpuRawUser.0&ssCpuRawIdle.0:password@localhost
	RouterUptime[xena2.cpu]: password@localhost
	MaxBytes[xena2.cpu]: 100
	Title[xena2.cpu]: User and Idle CPU usage- Xena
	PageTop[xena2.cpu]: <H1>User and CPU Load- Xena</H1>
	ShortLegend[xena2.cpu]: %
	YLegend[xena2.cpu]: CPU Usage
	Legend1[xena2.cpu]: User CPU in % (Load)
	Legend2[xena2.cpu]: Idle CPU in % (Load)
	LegendI[xena2.cpu]: User
	LegendO[xena2.cpu]: Idle
	Options[xena2.cpu]: growright,nopercent
	Unscaled[xena2.cpu]: ymwd

Make sure that LoadMIBs: /usr/local/share/snmp/mibs/UCD-SNMP-MIB.txt is in the Global Config Options section. Run these commands to load the changes:

	# env LANG=C mrtg /etc/mrtg.cfg
	# indexmaker --output=/var/www/mrtg/index.html /etc/mrtg.cfg

Mind your filepaths because they vary on different Linux distributions, and remember to run the first command until it quits emitting error messages, which should take no more than three tries.

So, point your web browser to localhost (http://localhost/mrtg), and admire your new graphs, which are now tracking two values:

	     Max    Average  Current
	User 9.0 %    8.0 %   6.0 %
	Idle 92.0 %  79.0 %  93.0 %

Discussion

There are two important changes in this example from the previous recipe. One is the target line—note that the OID pair are two different OIDs. The other change is the graph name. Every graph name must be unique.

You can tweak this in a number of ways. Here are the four main CPU object variables:

ssCpuRawUser

This tracks CPU usage by nonprivileged applications.

ssCpuRawNice

Tracks the CPU usage of nonpriority applications.

ssCpuRawSystem

CPU usage by privileged applications.

ssCpuRawIdle

Measures idle time.

You may use these singly or in combination. To track single values, remember that you still need to specify an OID pair, so you use the same one twice:

	Target[xena2.cpu]:ssCpuRawIdle.0&ssCpuRawIdle.0:password@localhost

And, remember to tweak your Legends and page titles accordingly.

See the Discussion in Recipe 14.7 for more information on configuration options, and man 1 mrtg-reference for detailed information.

See Also