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I've just started using atop to try to get to the bottom of some system bottlenecks.

I've found https://linux.die.net/man/1/atop which is very useful and explains most of what it does just fine.

What I'm curious about is what data atop shows when you very first launch it.

I ask because every time I launch it I have a red line that tells me swout 311826, and a cyan line telling me disk usage is at 67%.

After 10 seconds they both clear and go back to low levels (or in the case of the PAG line disappears).

Is it telling me the worst statistic from the past hour? Day? Ever? Or something else?

Codemonkey
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1 Answers1

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The initial display of atop contains metrics accumulated/averaged since the last reboot.

In particular swout is a sum of all swapouts since the last reboot. The disk busy 67% is an average (ouch!).

If you have historical data, the initial display of atop -r /var/log/atop/atop_20180613 contains metrics accumulated/averaged since the boot until 2018-06-13 00:00:00.

kubanczyk
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  • I only just installed it so I'm assuming those numbers are since installed rather than since the last reboot? – Codemonkey Jun 14 '18 at 08:40
  • These counters are maintained even when `atop` is not installed. It's only a reporting tool. @Codemonkey – kubanczyk Jun 14 '18 at 08:44