7.0-BETA3 (amd64): interrupt storm on atapci0

[Martin Matuska]

I have done some more investigation and have found out the following:

- after doing a fresh restart, the "rate" reported in "vmstat -i" does
not decrease. It keeps increasing slowly, when there is larger interrupt
activity on atapci0 (irq22)

- "systat -vmstat" reports zero interrupts, and "vmstat -i" reports this
increasing rate

- when utilizing the disks at 100% (copying large files) the interrupt
rate is about 2300, which is truly high, but this correct number is
shown only in "systat -vmstat"