ercan

#!/bin/bash

# NOTE: bc math library must be installed!

# Generates load with an empty loop
# Input parameter: Duration in seconds (Float)
full_load()
{
        duration=$1  # Input parameter
        st=`date +%s.%N`  # Start time of the loop <epoch seconds>.<nanoseconds>
        while true; do
                true
                # check if we should finish
                now=`date +%s.%N`
                is_end=`echo "($st + $duration) <= $now" | bc`
                if [ "$is_end" = "1" ]; then
                        return 1
                fi
        done
}

# This is the main loop that generates sinusoidal cpu load (for 1 cpu)
start=`date +%s`  # Record the script start time
while true; do
        # As seconds pass by, the amount of sleep changes according to cosine function
        # Start with cos(0) = 1
        diff_seconds=$((`date +%s` - $start))
        i=`echo "scale=4; c($diff_seconds / 20) + 1" | bc -l`  # c() is the cosine function

        # Full load for 1 second, sleep i seconds
        full_load 1
        sleep $i
        echo "$diff_seconds: Worked 1.0 s., slept $i s., expected load (%): "`echo "scale=4; (1/(1+$i)) * 100" | bc`
        echo "$diff_seconds "`echo "scale=4; (1/(1+$i)) * 100" | bc` >> data.txt
done