prompt script exiting

[William Cohen]

When running the testsuite with the recent version of systemtap 
(snapshot from this morning, 2005-12-02) I found that syscalls2.exp 
would consistently fail. The the tests uses an exit() in the script when 
a probe fires 100 times. The syscalls2.exp allows a little slop and the 
probe to fire after the exit but before being removed. However, the 
changes in how exit operates makes create a longer wait before scripts 
actually exits. On the test runs I saw the probe fire 232, 200, 267, and 
420 times on various machines, much more than the 150 times allowed in 
the test.

Do we expect the script to exit promptly when the exit() is encountered 
in the script? People taking measurements will want to know about this 
because it could significantly affect the data their scripts collect. 
For the time being we can just document this as how it behaves. It 
should be fairly easy for users to have a predicate in their 
instrumentation, so it is a pretty minor issue.

-Will