Why is 'CPU usage' unavailable in diagnostic tools?

I'm using Visual Studio 2015. When I use diagnostic tools, 'cpu usage' is always greyed out. Why?

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What are the causes of high CPU usage?

You can expect high CPU utilization when playing some games, running a video-editing or streaming application, performing an antivirus scan, or juggling many browser tabs.

Is it good If the CPU usage is 100?

CPUs are designed to run safely at 100% CPU utilization. However, you'll want to avoid these situations whenever they cause perceptible slowness in games.

If Performance Wizard is enabled other tools will be disabled because Performance Wizard uses a different collection approach. Please uncheck "Performance Wizard" to enable "CPU Usage". After you collected data using "CPU Usage" tool you can invoke "Create detailed report..." and you will get exactly the data provided by Performance Wizard in CPU Sampling mode.