CPU load & CPU stat

     user    nice   system  idle      iowait irq   softirq  steal  guest  guest_nice

cpu  74608   2520   24433   1117073   6176   4054  0        0      0      0

Algorithmically, we can calculate the CPU usage percentage like:

PrevIdle = previdle + previowait
Idle = idle + iowait

PrevNonIdle = prevuser + prevnice + prevsystem + previrq + prevsoftirq + prevsteal
NonIdle = user + nice + system + irq + softirq + steal

PrevTotal = PrevIdle + PrevNonIdle
Total = Idle + NonIdle

# differentiate: actual value minus the previous one
totald = Total - PrevTotal
idled = Idle - PrevIdle

CPU_Percentage = (totald - idled)/totald




cpu  114466 58760 208131 183612 1490 18 5178 0 0 0
cpu0 20966 6912 72976 161278 1200 3 3263 0 0 0
cpu1 18880 6959 39092 4213 20 5 112 0 0 0
cpu2 18665 6782 29917 4321 21 2 50 0 0 0
cpu3 18134 6434 27657 4442 21 2 62 0 0 0
cpu4 10008 8231 10491 2308 63 0 1003 0 0 0
cpu5 9338 8080 9868 2382 64 0 240 0 0 0
cpu6 9210 7570 9186 2392 40 2 226 0 0 0
cpu7 9265 7792 8944 2276 61 4 222 0 0 0



http://stackoverflow.com/questions/23367857/accurate-calculation-of-cpu-usage-given-in-percentage-in-linux