Experimental Physics and
Industrial Control System

Eric Norum <[email protected]> · Tue, 26 Nov 2002 20:52:46 -0600

On Tuesday, November 26, 2002, at 06:09  PM, Till Straumann wrote:

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.

How would this mesh with libtecla/libreadline? The shell task spends

most of its time blocked in these libraries waiting for input. How

could it reset the watchdog timer? (First person that says 'select'

gets a big raspberry from me!!!!)

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.

--
Eric Norum <[email protected]>
Department of Electrical Engineering
University of Saskatchewan
Saskatoon, Canada.
Phone: (306) 966-5394   FAX:   (306) 966-5407

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System