# QuestionHow to to calculate the equivalent utilization to each CPU speed clock. (for modeling purpose)

#### kingofdark

I am working on modeling to investigate the power consumption. I have no programme running on real machine to obtain the utilisation or power usage. I am using a modeling language and assuming the server CPU is AMD with following info:

 pstate Power Clock speed Voltage 0 95 2600 140 1 90 2400 135 2 76 2200 130 3 65 2000 125 4 55 1800 120 5 32 1000 110 Idle 15 ---- ----

I want anyone to help me to calculate the utilization that is related to each clock speed.
is there any formula can be used ?

is it correct for example to say the utilization at a (clock speed x) =x/maxclockspeed?

for example: what is might be the utilization when CPU clock speed = 2000?

#### Aeacus

##### Glorious
CPU frequency has nothing to do with CPU utilization since CPU frequency doesn't scale with CPU utilization. E.g at 2 GHz (2000 Mhz), CPU can be utilized 10%, 50% or even 100% depending on the task given to CPU.
Higher CPU frequency can shorten the time needed to complete the task at hand but that isn't always true. Efficiency is another critical part getting the task done. Efficiency is measured in terms of instructions per cycle (IPC). A CPU with a very high clock frequency, but low IPC, may not perform as well as a CPU with a lower clock frequency and high IPC.

It's like when you try to calculate car's speed based on it's engine RPM alone. It doesn't work like that. You have to consider transmission (gear amount and gear ratios), drivetrain, rim and tire size, friction and wind resistance as well. Gravity too if going up/down hill.

To calculate CPU utilization, here's further reading with formulas,