Your configuration has:
Target[cpu]: `/usr/bin/awk '/cpu /{print $2+$3; print $2+$3+$4; print "quite
some time"; print "domain.com"}'</proc/stat`
MaxBytes[cpu]: 100
Options[cpu]: nopercent,growright,noinfo,bits
You are getting your CPU info from /proc/stat, and the cpu line. However, this
line does not contain a count of seconds used.
See this page: http://www.linuxhowtos.org/System/procstat.htm
Since you are using counter mode (ie, no 'gauge' option) then you will be
graphing the rate of change of these counters. So far so good. But you want
this in percent, so basically, you need:
(CPU seconds used)/(seconds available)*100%
Now, the CPU count is NOT in seconds. It is in 'jiffies', which are typically
(but not always) 0.01 seconds. You can check the actual value of USER_HZ in
the include/asm/param.h file under your kernel source directory. Therefore,
you need:
((change in CPU count)/100)/(seconds available)*100%
Excellent - the 100s cancel out, and we should be OK! I assume you've already
worked things out this far...
But Wait! We have 4 CPUs on the machine, so the 'seconds available' is
actually 4 times the 'seconds passed'. This means we need:
(change in CPU count)/((seconds passed)*(number of CPUs))
The '/(seconds passed)' is done automatically by MRTG when it does its polling.
So, our Target definition needs to return:
(change in CPU count)/(number of CPUs)
The columns on the CPU line corresponds to:
* label
* user: normal processes executing in user mode
* nice: niced processes executing in user mode
* system: processes executing in kernel mode
* idle: twiddling thumbs
* iowait: waiting for I/O to complete
* irq: servicing interrupts
* softirq: servicing softirqs
Now, you want to graph (user time) and (total time used), which are ($2) and
($2+$4+$6)
Target[cpu]: `/usr/bin/awk '/cpu /{print ($2/4); print (($2+$4+$6)/4); print
"quite some time"; print "domain.com"}'</proc/stat`
So, lets try running that to test:
$ /usr/bin/awk '/cpu /{print ($2/4); print (($2+$4+$6)/4); print "quite some
time"; print "domain.com"}'</proc/stat
1.02992e+06
1.74553e+06
quite some time
domain.com
$
Oh no, what's gone wrong here? Awk is trying to be helpful and is printing in
exponential notation, which MRTG doesn't understand. This would probably
result in some very odd percentage calculations. So lets fix that:
$ /usr/bin/awk '/cpu /{printf "%f\n",($2/4); printf "%f\n", (($2+$4+$6)/4);
print "quite some time"; print "domain.com"}'</proc/stat
1029936.750000
1745558.750000
quite some time
domain.com
$
This gives us the definition:
Target[cpu]: `/usr/bin/awk '/cpu /{printf "%f\n",($2/4); printf "%f\n",
(($2+$4+$6)/4); print "quite some time"; print "domain.com"}'</proc/stat`
This is probably what we need. Set MaxBytes to 100 (as you have), and it
should work. If you are using the Routers2 frontend, then use the extended
options 'fixunit', 'nopercent' and 'nototal' so that the percentages are
handled correctly.
Steve
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