I'm working on an application for part of a school project that simulates an operating system and which I launch using the Terminal. By nature it will consume all possible resources to loop over and over. Is there a command or flag I can enter in Terminal to limit the amount of CPU it can utilize while it is running? I tried using the following command:

$ nice -n 20 ./a.out

to set the priority as low as possible, but it still took up 100% CPU to run. It's a rather simple program and hardly needs any resources to work properly so any limits imposed on it should be fine.

1 Answer 1


As nice only gives priority over over applications it won't stop 100% CPU usage.

Cputhrottle has worked for me in the past, though haven't checked it for 10.11 : http://www.willnolan.com/cputhrottle/cputhrottle.html

  • Will cputhrottle work if I often start and stop the process? I'll be debugging it so the process number will change often when it gets restarted.
    – intcreator
    Commented Jan 28, 2016 at 22:27

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