2

I would like to know why I have a process being able to report a usage line like:

PID   COMMAND  %CPU
248   Xcode    983.5

… in top on a quad core CPU?

I understand it's wrong, but how come? I'm not interested by Xcode going this high, but why top reports so high usage?

On OS X 10.7 with a Intel i7 quad core.

bwDraco
  • 46,683
jibay
  • 23

1 Answers1

1

It's just an extreme case of sampling error. Say your factory can generate one widget per hour and outputs them precisely on the hour. If someone were trying to measure your factory's output, they might sample from, say 8:50 to 10:10, and find that you output two widgets in 80 minutes. Converting to widgets per hour, they'd get 1.5, or 150% of capacity.

It could also be caused by turbo boost, thermal throttling, or power saving. But given the fact that your system was under near maximum load, I doubt it.

David Schwartz
  • 62,365