Watchdog, is just a quickly thrown together watchdog daemon for the Linux 
Watchdog interface in which a watchdog /dev entry is "patted" every couple 
of seconds.  If the device is not patted within a given time the machine 
is rebooted.  

This code goes further than just patting the device, it test 
disk io and memory allocate (crudly) to make sure the box is abit more 
than just alive.