Experimental Physics and
Industrial Control System

Till Straumann <[email protected]> · Tue, 26 Nov 2002 16:09:42 -0800

Here's yet another idea how the runaway-task problem could be solved.

AFAIK, most OS provide a hook into the system timer ISR but not

into the console ISR [which makes what we discussed at JLAB less

portable] - these hooks are vxWorks' watchdog timers, RTEMS' rtems_timers.

1) The shell task periodically resets (pets) a 'watchdog' counter.

2) A timer ISR increments 'watchdog'. Should 'watchdog' reach a critical
   'limit', this implies that the shell had no chance to pet.
   In this case, the ISR increments the task's priority and resets
   'watchdog'.

If a task with a priority > shell runs away, 2) will eventually raise

the shell's priority above the runaway task's and the user will regain

control.

-- Till

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System