Linux Networking Cookbook

14.7. Monitoring Active CPU Load

Problem

You want to use MRTG to keep an eye on CPU performance. cfgmaker only sets up graphs for your network interfaces. Now what?

Solution

You'll need to edit mrtg.cfg by hand. Don't use cfgmaker anymore because it will overwrite your changes. This recipe monitors system, user, and nice values, and adds them up to give a snapshot of CPU load.

Add this line to the Global Config Options section:

	# Global Config Options
	LoadMIBs: /usr/share/snmp/mibs/UCD-SNMP-MIB.txt,/usr/share/snmp/mibs/TCP-MIB.txt

Then, add this section at the bottom of the file:

	# monitor CPU load
	#
	Target[xena.cpu]: ssCpuRawUser.0&ssCpuRawUser.0:password@localhost + ssCpuRawSystem.
	0&ssCpuRawSystem.0:password@localhost + ssCpuRawNice.0&ssCpuRawNice.0:
	password@localhost
	Title[xena.cpu]: Xena CPU Load
	RouterUptime[xena.cpu]: password@127.0.0.1
	PageTop[xena.cpu]: <H1>CPU System, User and Nice stats for Xena</H1>
	MaxBytes[xena.cpu]: 100
	ShortLegend[xena.cpu]: %
	YLegend[xena.cpu]: CPU Usage
	Legend1[xena.cpu]: Current CPU percentage load
	LegendI[xena.cpu]: Used
	LegendO[xena.cpu]:
	Options[xena.cpu]: growright,nopercent
	Unscaled[xena.cpu]: ymwd

While you're there, you might as well delete the entry for the loopback device, as you're not going to use it anyway. Now, run mrtg manually three times, or until it stops complaining, and mind your filepaths:

	# env LANG=C mrtg /etc/mrtg.cfg

Then, generate a new index.html page:

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

Now, you should ...