How to Create a CPU Spike with a Bash Command

How to create a CPU spike with a bash command

You can also do

dd if=/dev/zero of=/dev/null

To run more of those to put load on more cores, try to fork it:

fulload() { dd if=/dev/zero of=/dev/null | dd if=/dev/zero of=/dev/null | dd if=/dev/zero of=/dev/null | dd if=/dev/zero of=/dev/null & }; fulload; read; killall dd

Repeat the command in the curly brackets as many times as the number of threads you want to produce (here 4 threads).
Simple enter hit will stop it (just make sure no other dd is running on this user or you kill it too).

Bash: wait until CPU usage gets below a threshold

wait_for_cpu_usage()
{
    current=$(mpstat 1 1 | awk '$12 ~ /[0-9.]+/ { print int(100 - $12 + 0.5) }')
    while [[ "$current" -ge "$1" ]]; do
        current=$(mpstat 1 1 | awk '$12 ~ /[0-9.]+/ { print int(100 - $12 + 0.5) }')
        sleep 1
    done
}

Notice it requires sysstat package installed.

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