This morning monitoring sent an alarm: the server's load average is above three. The machine has a single CPU, yet commands in the terminal answer at once. Look at the load yourself.
Look at the load
Look at the load average in the uptime output, the number of CPUs on the machine and the %Cpu(s) line in top.
First, predict
The load average is above three, and the machine has one CPU. What will top show in the id field of the %Cpu(s) line — the share of time the CPU is idle?
Now start the exercise, run the command and compare your prediction with the output.
The load average is above three on a single CPU, while top shows the CPU almost free. Is the CPU overloaded?
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An overloaded CPU is never idle: top would show an id near zero, and commands would answer with a delay.
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Run
top -bn1 | head -3a few times: id is about 90% or more every time.
The CPU is free while the load average is high: the load average counts more than work on the CPU.