how to fix "interrupt storm"

[perryh at pluto.rain.com]

"Paul B. Mahol" <onemda at gmail.com> wrote:
> On 5/9/09, perryh at pluto.rain.com <perryh at pluto.rain.com> wrote:
> > "Paul B. Mahol" <onemda at gmail.com> wrote:
> >> On 5/8/09, perryh at pluto.rain.com <perryh at pluto.rain.com> wrote:
> >> > What, exactly, is an "interrupt storm", and how do I fix it?
> > ...
> >> >   interrupt storm detected on "irq9:"; throttling interrupt source
> >> >   interrupt storm detected on "irq9:"; throttling interrupt source
> >> >   interrupt storm detected on "irq9:"; throttling interrupt source
> >> >   interrupt storm detected on "irq9:"; throttling interrupt source
> >> >   interrupt storm detected on "irq9:"; throttling interrupt source
> >> >   ad6: FAILURE - SET_MULTI status=51<READY,DSC,ERROR> error=4<ABORTED>
> >> >   ad6: TIMEOUT - READ_DMA retrying (1 retry left) LBA=136936
> >> >
> >> > etc. etc. until I killed it with ^C.  (Just entering "q", to cause
> >> > more(1) to exit and presumably stop od(1) with a SIGPIPE, did not
> >> > stop the spew of messages.)
> >> >
> >> > What does this indicate?  Hardware problems?  Bad configuration?
> >> > Something else?
> >>
> >> Output of "vmstat -i"?
> >
> > $ vmstat -i
> > interrupt                          total       rate
> > irq0: clk                      497386851       1004
> > irq1: atkbd0                        2491          0
> > irq3: xl0                           2030          0
> > irq6: fdc0                            11          0
> > irq7: ppbus0 ppc0                      1          0
> > irq8: rtc                       63654324        128
> > irq9: uhci0+                      166216          0
>
> uhci0 is doing strange things, what usb device are connected?

There are no USB devices connected.  I think those must actually
be atapci1 interrupts, since irq9 is where dmesg reported it.

> It could be bad configuration, bug or hardware problem.