Re: [9fans] Question regarding interrupt handlers

[Sape Mullender <sape@plan9.bell-labs.com>]

> How do interrupt handlers in Plan 9 cope with large amounts of work
> having to be done in order to handle an interrupt?
> Is there a way to split the task in two parts, one to be handled
> immediately and the other to be executed at a more convenient time?
>
> Are there standard approaches for this problem in Plan 9, similar to the
> approach of tasklets and bottom half processing in Linux?

You can create a kernel process (look at the implementation of --
and calls to -- kproc in the kernel) that deals with the bulk of the work
of the handler.  Alternatively, you can let a user process dod the bulk
of the work in the device driver.  The interrupt could be used to set
the driver in motion.  The driver would do a sleep() and the interrupt
routine a wakeup().  You can use ilock() for mutual exclusion between
driver and interrupt routine (but you're not supposed to hold an ilock
for more than a handful of instructions).

	Sape