Comment 14 for bug 665796

Kalidarn: the "timer" interrupt must ALWAYS increment. It is produced continuously by the hardware, hundreds or thousands of them per second. watch keeps running that command every 2 seconds, so, the number is always changing. The kernel uses this interrupt mainly for process scheduling. If for some reason the interrupt stops, the kernel won't be able to do proper scheduling, and the system becomes sluggish.

There are other sources of hardware interrupts. Every time a hardware device causes an interrupt, the kernel awakens to process that interrupt. If the timer interrupt is not working, then all wakeups are to process hardware events, and this causes monitors to report very high System CPU usage.

I'm using the CFQ I/O scheduler. It seems that Core i7 and nVidia proprietary drivers are the common characteristics of all people reporting this issue, I'll update the title.