Server Fault is a question and answer site for system and network administrators. 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

Ubuntu 10.04 kernel 2.6.36

some of our VPS's were crashing the last few days due to cpu load with Java (cpu_hung for 120 seconds errors on console) installing irqbalance seems to have resolved the issue.

But, it did not require a reboot after installing. Is this normal? I am asking because this is something I need to install on all my servers and I need to be 100% sure irqbalance does not require a reboot.

share|improve this question

Typically, Ubuntu and other Debian-based distros will start a service as soon as it's installed; Red Hat based distros do not.

In either case it's not necessary to reboot; if the service hadn't been started automatically as part of the installation, you could have started it yourself.

share|improve this answer
Thanks.I was wondering how the process/service (irqbalance) could actually take control of CPU requests and "balance" them accordingly without a reboot after the service is installed. – Tom G Jul 10 '12 at 18:06
irqbalance (and any other service) starts working as soon as the service is started. Since Ubuntu starts services automatically when you install them, you should be set. – Michael Hampton Jul 10 '12 at 18:07
@TomG: It begins monitoring IRQs being received and updating the CPU IRQ masks. Any process (with suitable permissions) can do either thing at any time. For example, cat /proc/interrupts (show interrupts by CPU) or echo 1 | /proc/irq/9/smp_affinity (set IRQ 9 to be handled only by CPU 0). You can even run irqbalance in one shot mode to just set the IRQ-to-CPU mapping once and then terminate. – David Schwartz Jul 10 '12 at 19:22
thanks David - got it. – Tom G Jul 10 '12 at 19:35

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.