Getting rid of "Interrupt storm detected on "vec2024: puc0 puc1"

John Baldwin jhb at
Mon Jan 9 10:31:56 PST 2006

On Monday 09 January 2006 10:19 am, Bruce O'Neel wrote:
> Hi,
> I get the following message:
> Interrupt storm detected on "vec2024: puc0 puc1";
>  throttling interrupt source
> and then, suprise suprise, the mouse quits working in X.  Sadly X is
> less functional without a mouse.
> I think the problem is the null modem cable to a sparc20 console.
> Is there:
> - an easy way to say "ok, I think I've fixed the problem, can we
> start over" short of rebooting?

If the interrupt stops storming the ithread code will notice and stop 
throttling it.  It only throttles the source to hz interrupts per second 
while the storm is active.

> - an easy way to know what might be wrong?  Is there some way to see
> the interrupt rate so that I could know if unplugging the console cable
> fixes it?

vmstat -i will show you the interrupt counts.  systat -vmstat can give a 
better since of the current rates.  Probably there's a bug in a driver in 
that the device is signalling a condition the driver doesn't handle, so the 
interrupt is never handled from the device's perspective.

John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve"  =

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