On Wed, Nov 12, 1997 at 07:28:17PM -0800, James Graham - Systems Mangler wrote:
>  * > >So something's blocking interrupts for too long.
>  * > >
>  * > Is there a way to profile this, or log interrupts to see what it might be?
>  * 
>  * Maybe one could write the interrupt level into a parallel port every time
>  * the system enters an interrupt routine and then monitor the parallel port
>  * pins to see what is going on..  (An oscilloscope or logic analyzer
>  * required.)
> 
> Great idea.
> 
> Problem:  Sun4c has no parallel port.

I know that all too well.  Someone just suggested that the interrupt latency
problem affects all ports (which I think is true) and many platforms _do_
have parallel ports..

I guess you could also set the serial port to the maximum speed and write
information (single bytes) to it at the beginning and end of interrupt
processing.

  -jm