System Idle Process
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Windows Task Manager in Windows XP showing System Idle Process usage at 99%, indicating that no other process is using significant CPU time. | |
Operating system | Microsoft Windows |
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Type | Kernel |
In
The primary purpose of the idle process and its threads is to eliminate what would otherwise be a special case in the scheduler. Without the idle threads, there could be cases when no threads were runnable (or "Ready" in terms of Windows scheduling states). Since the idle threads are always in a Ready state (if not already Running), this can never happen. Thus whenever the scheduler is called due to the current thread leaving its CPU, another thread can always be found to run on that CPU, even if it is only the CPU's idle thread. The CPU time attributed to the idle process is therefore indicative of the amount of CPU time that is not needed or wanted by any other threads in the system.
The scheduler treats the idle threads as special cases in terms of thread scheduling priority. The idle threads are scheduled as if they each had a priority lower than can be set for any ordinary thread.
Because of the idle process's function, its CPU time measurement (visible through, for example,
In Windows 2000 and later the threads in the System Idle Process are also used to implement
There are more detailed sources of such information available through Windows' performance monitoring system (accessible with the perfmon program), which includes more finely grained categorization of CPU usage. A limited
See also
- List of Microsoft Windows components
- Idle (CPU)
- Microsoft Windows
- HLT (x86 instruction)
- Process Explorer
References
- ISBN 0-7356-1917-4.
- "What Is "System Idle Process," and Why Is It Using So Much CPU?". How-To Geek. Retrieved 2022-01-13.
- "system idle process - What is system idle process?". www.processlibrary.com. Retrieved 2022-01-13.