stap early exit

[Frank Ch. Eigler]

Jim Keniston <jkenisto@us.ibm.com> writes:

> A SystemTap user at IBM is seeing his stap script terminate after a few
> minutes, for no reason that he or I can figure out.  The final message
> is:
> stapio:cleanup_and_exit:229 closing control channel
>[...]
> dvhltc@us.ibm.... stapio:cleanup_and_exit:229 closing control channel
> Pass 5: run completed in 50usr/120sys/213446real ms.

Indeed odd.  A few things to try to help narrow it down:

- check if the phenomenon reoccurs
- check if it's a regular time interval
- change the "flag[tid()] = 0" to "delete flag[tid()]"
- try removing the print_backtrace() calls
- run with "stap -t"
- check whether any probes were skipped
- see whether the stap* processes may have operated under some 
  resource limit like cpu time
- try bumping up buffer size


- FChE