CPU Utilization is Wrong (2017)

brendangregg.com

40 pointsadityaathalye5 comments

Related recent discussion: "%CPU utilization is a lie".

Thanks! I was just coming here to mention that. Macroexpanded:

%CPU utilization is a lie - https://news.ycombinator.com/item?id=45110688 - Sept 2025 (162 comments)

Also these past discussions of the OP:

CPU Utilization Is Wrong (2017) - https://news.ycombinator.com/item?id=36580006 - July 2023 (57 comments)

CPU Utilization Is Wrong - https://news.ycombinator.com/item?id=23827032 - July 2020 (1 comment)

CPU Utilization is Wrong - https://news.ycombinator.com/item?id=14301739 - May 2017 (91 comments)

I always understood it "how many CPU cores would I need so that they all run at 100%"

E.g. if I have 1 core and utilization is 3 then if I had 3 cores they would run exactly at 100%

The problem (or really, nuance) comes when you try to define what "run exactly at 100%" means.

Yeah, I love the expression the "Flaw of the Averages".

Depends on what you're counting, among other things. (Not to mention when you took the samples being averaged).