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Subject: Re: base max thread priority
From: Eric Norum <eric.norum@usask.ca>
To: Till Straumann <strauman@SLAC.Stanford.EDU>
Cc: Jeff Hill <johill@lanl.gov>, 'Marty Kraimer' <mrk@aps.anl.gov>, "'Johnson, Andrew N.'" <anj@aps.anl.gov>
Date: 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 <eric.norum@usask.ca>
Department of Electrical Engineering
University of Saskatchewan
Saskatoon, Canada.
Phone: (306) 966-5394   FAX:   (306) 966-5407


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Re: base max thread priority Till Straumann
References:
Re: base max thread priority Till Straumann

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