0

I noticed a discrepancy in Task Manager between the performance tab and the details tab. Performance tab shows 14% utilization, while the numbers in the details tab add up to about 5%. I know there are small rounding errors in the details tab, but this question is not about that. One process osd.exe shows 4% in the details tab, while it shows 10.2% in Process Explorer. This screenshot shows both open simultaneously. Also at the same time, the Task Manager processes tab shows 9.2% for this process.

The total utilization shown at the bottom of Process Explorer matches the performance tab of Task Manager.

Also, Python's psutil.cpu_percent() shows 6.6% which is pretty close to the sum of the Task Manager details tab since the details tab rounds to the nearest integer.

Apparently these different views are using 3 different methods to calculate CPU consumption. I would love to find some documentation showing the differences. This is on Windows 10.

I also checked it with high CPU utilization by running Prime95 torture test:
Task Manager details tab 90%
Task Manager processes tab 83%
Python psutil 100%
Process Explorer 83%

I believe Python and Task Manager details tab are accurate because Prime95 is supposed to push the CPU to its limit, but I'm not sure.

enter image description here

Elliott B
  • 1,103
  • 4
  • 13
  • 35
  • The CPU usage changes rapidly. You need to be looking at at 3 screens **at the same time** – DavidPostill Sep 02 '20 at 20:06
  • Click on the first process explorer graph at the top left and you will see it change over time (sometimes quite rapidly depending on what else you have running). – DavidPostill Sep 02 '20 at 20:09
  • There's also the fact that the performance tab is doing a lot more querying of various system performance metrics such as disk utilisation and usage for multiple disks, GPU utilisation and other things such as the processing and construction of multiple graphs over "just" task details. – Mokubai Sep 02 '20 at 20:10
  • The fluctuation is only +/- 0.5%. That does not explain this 6% discrepancy between TaskMan and ProcExp – Elliott B Sep 02 '20 at 20:11
  • One diff between Process Explorer + Performance tab is they include System Interrupts and Deffered Procedure calls that are not associated with any given process and are thus not visible in the processes tab. see here: https://superuser.com/questions/852656/what-is-the-system-interrupts-process-in-windows/852659#852659 – Frank Thomas Sep 02 '20 at 20:27
  • @FrankThomas I am talking about one specific process `osd.exe` in this example. – Elliott B Sep 02 '20 at 20:45

0 Answers0