"Hang watch" is not a familiar term to me and Google does not seem to find anything useful about it either.
Do you mean the hangcheck timer?
It's a kernel feature. It can be either compiled-in to the kernel, or as a kernel module (named "hangcheck-timer").
If the hangcheck timer is enabled, you should see a message similar to this among the boot messages:
Hangcheck: starting hangcheck timer
(tick is 60 seconds, margin is 180 seconds).
The hangcheck-timer was developed for Linux by Oracle. Here's some documentation on its use:
http://www.rampant-books.com/art_hunter_rac_oracle%20linux_hangcheck_kernel_module.htm
MK
MK
