[Tinyos-devel] Nested interrupts

[David Gay]

On 8/12/07, John Regehr <regehr at cs.utah.edu> wrote:
> Small puzzle problem: Is there ever a legitimate (i.e., correct and
> appropriate) use of a reentrant interrupt handler?

That's easy ;-) Temporary overcommitting of the "CPU cycles" resource.
I.e., with nested interrupts you can possibly:
- process two identical interrupts which occur in very close
succession which you couldn't handle w/o allowing reentrancy.
- tolerate more jitter in the execution time of an interrupt handler
(example: every 50th interrupt takes twice as long as usual, such that
the 51st interrupt overlaps with the execution of the 50th - but the
processor "catches" up before the 100th)

In both cases, you do have to be extremely careful in your interrupt handler ;-)

David Gay