ozMonitor Knowledge Base - Workshop : Follow-up of the CPU with MRTG

Various pieces of information about kernel activity are available in the /proc/stat file. All of the numbers reported in this file are aggregates since the system first booted. For a quick look, simply cat the file:

The very first "cpu" line aggregates the numbers in all of the other "cpuN" lines. These numbers identify the amount of time the CPU has spent performing different kinds of work. Time units are in USER_HZ (typically hundredths of a second). The meanings of the columns are as follows, from left to right:

Initially, it will be necessary to put the script below in your /etc/mrtg directory

Script Name : cpu.pl

Contents:

#! /usr/bin/perl
my $cpu = `cat /proc/stat | grep “CPU” `;
$cpu=~ /cpu (. *) (. *) (. *) (. *)/;
my $conso = $1 + $2 + $3;
$conso = int ($conso);
print “$conso \ N”;
print “$conso \ N”;

Once, /etc/mrtg/cpu.pl script set up, its rights are changed as follows:

chmod +x /etc/mrtg/cpu.pl

Check your script by :

# /etc/mrtg/cpu.pl
35583547
35583547

Then, it will be necessary to update your /etc/mrtg.cfg configuration file, and this with the following contents:

Target [localhost-CPU]: `/etc/mrtg/cpu.pl `
Options [localhost-CPU]: noinfo, nopercent, growright, nobanner, noi
[Localhost-CPU]: Follow-up of the consumption of the CPU
MaxBytes [localhost-CPU]: 9999999999
YLegend [localhost-CPU]: CPU
ShortLegend [localhost-CPU]: %
LegendO [localhost-CPU]: CPU
Legend2 [localhost-CPU]: CPU
PageTop [localhost-CPU]: Follow-up of the consumption of the CPU

The construction of the new index page (the new synthesis web page) is done using indexmaker command. Here an example:

cp /var/www/mrtg/index.html /var/www/mrtg/index.html.old
indexmaker --columns=1 --output /var/www/mrtg/index.html /etc/mrtg.cfg