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Puzzled by the sar command output

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the_bro
the_bro Posts: 20
in LFS201 Class Forum - Discontinued

In the System Monitoring section, the command sudo sar 3 3 is run; the resulting report shows the system is idle twice for 100% of the time.
How can that be? Surely if a system is not doing anything it must be hung or stopped and if it's in either of these states, how can it run again 3 seconds later?
I've run the command many times and have failed to duplicate this!

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  • coop
    coop Posts: 915
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    There is nothing wrong with the output. It is just rounding up to 100 percent I guess--the system was really really idle. For example on a system I am running right now (RHEL 8):

    c8:/home/coop>sudo sar 3 3
Linux 5.16.0 (c8)   01/15/2022  _x86_64_    (8 CPU)

09:08:30 AM     CPU     %user     %nice   %system   %iowait    %steal     %idle
09:08:33 AM     all      0.21      0.00      0.13      0.00      0.00     99.67
09:08:36 AM     all      0.25      0.00      0.04      0.00      0.00     99.71
09:08:39 AM     all      0.17      0.00      0.08      0.04      0.00     99.71
Average:        all      0.21      0.00      0.08      0.01      0.00     99.69

    Pretty close to 100 percent, which I agree is a little unexpected but not wrong.

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