Measuring Actual CPU Speed & Frequency

As a good administrator, of course, you know at what speed your machines run because you have an eye on your CPU usage at any time – but do you? Modern CPUs do not make things easy.

Let me go back in time a little bit. Several years ago, I was overclocking my computer’s CPU. I played a lot with different cooling fans and thermal greases to get the most out of my old Intel Pentium workhorse. I think two or more CPUs ended up as very expensive bricks because I did not manage the heat correctly.

However, those were simple times. A CPU with 400 MHz continually delivered 400 MHz.

Modern CPU Functionalities

Then, along came Intel Turbo Boost. It adjusts each core’s frequency dynamically according to load and thermal budget. If the CPU gets too warm, overclocking stops automatically. Thus, the risk of overheating the processor is mitigated. With Turbo Boost, overclocking was suddenly possible in the server area – where the consequences of hardware failure are even more grave.

To reduce power consumption, further functionalities found their way into modern CPUs. One of them was C-states. It lets you save energy by cutting the clock signals used inside the CPU as well as by reducing the CPU voltage.

Frequencies And Utilization

As a result of all these functionalities, one has to deal with different CPU frequencies:

  • Maximum frequency
  • Base frequency
  • Actual frequency

Your first stop to review them is Windows Task Manager (note, it uses the term “speed” instead of “frequency”). But, Task Manager is lying to you. The screenshot below displays a maximum speed of 3.50 GHz. That is wrong. The label Maximum speed should read Base speed. In fact, the maximum speed is 3.80 GHz, for this CPU model.

Here is another thing. One might assume that the 20 percent utilization refers to the base speed. It does not. The utilization always refers to the actual CPU speed, which was 2.07 GHz at the time the screenshot was taken.

Make Use of The Data With uberAgent

But don’t worry, even if you are a little confused by the different kinds of frequencies. With version 5.0, we have enhanced our Machine Performance dashboard. It now shows you the average actual CPU frequency as a percentage of the base frequency. This enables you to compare the energy efficiency of different platforms.

In addition, we have added the CPU’s base speed and the average actual speed to the Single Machine Detail dashboard, which allows you to analyze your machine’s efficiency even further.

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