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What is the command to see CPU load of a RedHat Linux server?

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top - The classic approach

enter image description here

htop - The colorful approach

enter image description here

mpstat - The plain and simple

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If you're wondering how to read the CPU load from the output of top or mpstat, please look at the idle values they print. The CPU load is the difference between 100% and the displayed value.

If you think that that's weird, please see our question: How is the percentage of CPU usage calculated?

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Thanks, but it gives cpu load per process. I want to see total CPU load, for example 85% – alwbtc Jul 29 '12 at 13:55
If you look at the top line in the first image (program top). It has the line load average. The three values after that are the load average over time. – Hennes Jul 29 '12 at 14:06
@alwbtc: They all give you that in various forms. If you look at the output of mpstat you see an idle value of 99.24. This means I have a CPU load of 0.76%. As @Hennes notes, there is also the load average displayed, which is another indicator of CPU load. If you really only want a command that returns a single percent value, you'll probably want to post-process the output of mpstat. – Oliver Salzburg Jul 29 '12 at 14:17
+1 for helpful images! – BrianAdkins Jul 29 '12 at 14:30

Personally I think looking at the average load of a period is best. Otherwise you might get quite different values depending on the timing. (e.g. enter a command and press [Enter] might yield a different result than if you pressed [Enter] a fraction of a second later.)

Some ways of checking the load average are:

  1. cat /proc/loadavg

    beetle:/proc>cat loadavg
    0.45 0.19 0.13 1/263 17588

  2. uptime also shows the load.

    4:03PM  up 155 days, 19:12, 38 users, load averages: 0.16, 0.17, 0.12

  3. Via top. Look at he line load averages: in the upper right corner.

  4. htop

  5. mpstat

  6. systat (e.g. systat -vmstat)

Most of these programs give you three numbers:

  • The load average during the last minute.
  • The load average during the last five minutes
  • The load average during the last fifteen minutes.

If you have one core then a load of 1 more or less indicates that core is busy 100% of the time. This number can exceed 1 (or 100%). If that happens there is on average more then one process in the run queue.

If you have multiple CPU's then 100% (or 1.00) means that one average one core is busy all the time. E.g. with 4 core this could mean 1 core running flat out and 3 cores being idle. Or 4 cores running ¼ of the time.

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Thanks, load average 0.45 means: 45% of CPU power is used? – alwbtc Jul 30 '12 at 9:57
0.45 means that 45 of a single CPU core is used. 45% used, 55% idle. ---- If you have two core and get a load of 0.45 then 45% of a core is used and 155% is idle ; or both core are used 22.5% of the time and both core are idle 77.5% of the time. – Hennes Jul 30 '12 at 12:19

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