Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I want to make cpu0 offline. I have dual core laptop. I can make cpu1 offline ( using offline file ) but can't make cpu0 offline. How to do this ?

share|improve this question
Are you trying to take cpu0 offline after taking cpu1 offline, or are you trying to do this separately? – Jeremy Kerr Nov 13 '12 at 5:20
No. I want to make cpu0 offline only. ( while keeping cpu1 online ) – Viraj Nov 13 '12 at 6:00

to enable a cpu0

you can use this

echo 1 | sudo tee /sys/devices/system/cpu/cpu0/online

and to disable

echo 0 | sudo tee /sys/devices/system/cpu/cpu0/online
share|improve this answer

I've also found, certain systems cannot disable CPU0. I think usually this happens because the interrupt line is wired to CPU0, so the APIC cannot signal CPU1 on up (turning off CPU0 would cut off all interrupts and the system would lock up.)

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.