Using GNUplot to graph process CPU usage
At a friend’s request and out of plain curiosity, I went about trying to find a way to graph per-process CPU usage over time. So I wrote this tiny script that grabs a certain PID’s CPU usage every 3 seconds for however long the user specifies, and when it’s done, it outputs a nice ASCII chart of the CPU usage, courtesy of GNUplot.
Here’s the script:
#!/bin/zsh
if (( ! $# )); then
echo "Usage: $0:t <PID> <minutes to monitor>" >&2
return 1;
fi
let "ticks=$2*60/3"
for i in {1..$ticks}; do;
ps -p $1 -o pcpu | grep -v % >> $1-usage.txt;
sleep 3;
echo $i / $ticks;
done;
gnuplot -e "set term dumb; set yrange [0:100]; \
plot '$1-usage.txt' s c;"
And here’s the output:
100 ++------+------+-------+------+-------+------+-------+------+------++
+ + + + + + 'usage-mplayer.txt'+****** +
| |
| |
80 ++ ++
| |
| ******************* |
******************* * ******|
60 +* * *** ++
| * ** |
| * * |
| * * |
| * * |
40 ++ * * ++
| * * |
| * * |
| * * |
20 ++ * * ++
| * * |
| ******************* |
+ + + + + + + + + +
0 ++------+------+-------+------+-------+------+-------+------+------++
0 100 200 300 400 500 600 700 800 900
And GNUplot also does graphical charts! Take the <PID>-usage.txt file dropped in your cwd by the script and run it thru GNUplot like this:
gnuplot -e "set term png; set output graph.png; \
set yrange [0:100]; plot 'PID-usage.txt' s c"
The numbers on the X axis are ticks (seconds/3), the numbers on the Y axis are CPU usage.
Required for this script: zsh, gnuplot and… ps.
