When Kworkers Don't

I recently had the problem where kworker threads were taking up 100% on my Ubuntu box.

Various threads seem to suggest the problem lies with interrupts around PCI or power saving features. The thread with the answer that worked for me, "HELP !!! Zombie attack ... (kworker)"

To turn both of them off use:
noapic acpi=off

I found I only needed to turn off acpi though:
acpi=off

Put that in your grub configuration (sudo vi /etc/default/grub) and restart.

I hate not knowing why though.