Probe average cpu utilisation (MRTG)
21 Oct 2004There are two main tools to keep track of your CPU usage: top and vmstat.
topis an interactive tool: it shows you the CPU usage of each process, as well as overall statistics, updated every 5 seconds. It’s good for hands-on checking.
<br /> #top 17:18:34 up 2 days, 8:14, 3 users, load average: 0.00, 0.00, 0.00<br /> 47 processes: 46 sleeping, 1 running, 0 zombie, 0 stopped<br /> CPU states: 0.1% user 0.1% system 0.0% nice 0.0% iowait 99.6% idle<br /> Mem: 1030872k av, 1022256k used, 8616k free,<br /> 0k shrd, 104844k buff<br /> 777088k actv, 12k in_d, 22296k in_c<br /> Swap: 2048276k av, 8120k used, 2040156k free<br /> 640080k cached<br /> PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND<br /> 30776 root 19 0 1140 1140 852 R 0.9 0.1 0:00 0 top<br /> 1 root 15 0 504 464 436 S 0.0 0.0 0:03 0 init (...)
But say you want to get just one number (percentage) back, so you can use it for logging.vmstatwil give you the following output:
<br /> #vmstat<br /> procs memory swap io system cpu<br /> r b w swpd free buff cache si so bi bo in cs us sy id<br /> 0 0 0 7964 8804 104712 640224 0 0 2 16 129 27 0 0 100<br /></p> You can runvmstat 1 5to get 5 consecutive measurements (1 second apart). The number we want is the average CPU usage, or (100% – idle). The following command will do the job:
#vmstat 1 5 | gawk "/0/ {tot=tot+1; id=id+$16} END {print 100 - id/tot}"
gives
0.4</li> </ul>
