mpt, interrupt storm detected, different IRQ

[venom]

Hello

problem
interrupt storm detected

FreeBSD 8.1-RELEASE amd64

-- from /var/log/messages
interrupt storm detected on "irq16:"; throttling interrupt source

|# vmstat -i | awk "/rate|mpt|uhci/"
interrupt                          total       rate
irq16: uhci3 uhci4*               430408        786
irq19: uhci0 uhci1*                   26          0
irq24: mpt0                       375534        686|

# mptutil show adapter
mpt0 Adapter:
        Board Name: SAS3801E
    Board Assembly: L3-01123-04E
         Chip Name: C1068E
     Chip Revision: UNUSED
       RAID Levels: none

interrupt storm detected on mpt activity, usb devices is not connected

problem in mpt driver ?

/Vladimir Ermakov