interrupt storm on irq 10

David Kelly dkelly at
Wed May 27 19:14:02 UTC 2009

On Wed, May 27, 2009 at 12:51:45PM -0500, Andrew Gould wrote:

> Are interrupt storms a problem?  Do I need to worry about them?  If
> so, is there anything I can do about them?

Have run across interrupt storms for the first time myself last night.
Am thinking they are from interrupt sources that interrupt handlers do
not fully support. So the interrupt is not being serviced and is
repeatedly being invoked.

Probably PCI doesn't behave the same as much simpler embedded hardware
that I am used to, but the above is what an interrupt storm looks like
on simple embedded hardware.

My source of interrupt storms was caused by a bad SATA cable. Installed
a new VIA 6421-based SATA card (selected because it was only $15) and
two new hard drives for the purpose of copying files off two older
drives. New drives were detected but ad4 did not work when ad6 did.
Swapped drives and the other drive on ad6 worked. Thought the card was
bad but decided to try swapping cables which fixed ad4 and broke ad6.
Ergo, bad cable.

David Kelly N4HHE, dkelly at
Whom computers would destroy, they must first drive mad.

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