private fun getPercentCpuUsage(pid: Int): Double {
    return (getCpuUsage(pid) / getTotalCpu()) * 100
}

private fun getCpuUsage(pid: Int): Double {
    val reader = BufferedReader(FileReader("/proc/$pid/stat"));
    val sa = reader.readLine().split("[ ]+".toRegex(), 18);
    val usage = sa[13].toDouble() + sa[14].toDouble() + sa[15].toDouble() + sa[16].toDouble();
    reader.close();
    return usage
}

private fun getTotalCpu(): Double {
    val reader = BufferedReader(FileReader("/proc/stat"));
    val sa = reader.readLine().split("[ ]+".toRegex(), 9);
    val work = sa[1].toDouble() + sa[2].toDouble() + sa[3].toDouble();
    val total =
        work + sa[4].toDouble() + sa[5].toDouble() + sa[6].toDouble() + sa[7].toDouble();
    reader.close();
    return total;
}