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How is CPU % in Performance tab of Task Manager determined

Priya Jagyasi 21 Reputation points
2024-11-12T16:50:38.8733333+00:00

I am looking to understand how is CPU% determined in Task Manager. I am observing a difference between CPU% in perfmon tool using % Processor Time counter. Please see attached snapshot.

Which one is correct? What is causing the difference? Screenshot (7).png

Windows development Windows Performance Toolkit
Windows for business Windows Client for IT Pros User experience Other
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  1. Castorix31 90,681 Reputation points
    2024-11-13T07:58:09.5766667+00:00

    I'm not 100% sure, but, from my tests on Windows 10, Task Manager seems to concatenate times from each process

    (NtQuerySystemInformation with SystemProcessInformation with SYSTEM_PROCESS_INFORMATION structure)

    Perfmon uses Performance Counters

    Task Manager uses them for GPU ("\GPU Engine()\Utilization Percentage"* and others, but apparently not for CPU (but to be confirmed..))

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