Glossary
kernel_task
The macOS kernel, shown as a process. High CPU usually means it is managing heat.
What it is
kernel_task represents the core of macOS in Activity Monitor. Its CPU figure includes work the kernel does for the whole system.
Apple explains that one of kernel_task's jobs is managing CPU temperature: when the CPU gets too hot, kernel_task makes the CPU less available to the processes using it heavily. It doesn't cause the heat, and its activity falls as temperatures fall.
Why it matters
You can't quit kernel_task, and you shouldn't try. When it is busy, look for what is generating heat.
In Activity Monitor
A process named kernel_task in the CPU tab, usually near the top when the Mac is hot.
In iKnowMyMac
System processes are grouped under a macOS row. The thermal state and throttling alerts show when heat is the real issue, and diagnosis names the apps using the most energy.
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