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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.

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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.

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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
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