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<== Date ==> <== Thread ==>

Subject: Re: base max thread priority
From: Till Straumann <strauman@SLAC.Stanford.EDU>
To: Jeff Hill <johill@lanl.gov>
Cc: 'Eric Norum' <eric.norum@usask.ca>, 'Marty Kraimer' <mrk@aps.anl.gov>, "'Johnson, Andrew N.'" <anj@aps.anl.gov>
Date: 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


Replies:
Re: base max thread priority Eric Norum
References:
RE: base max thread priority Jeff Hill

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