[Bug testsuite/16493] New: Improve bkl.stp to add backtrace and timeout

[Bug testsuite/16493] New: Improve bkl.stp to add backtrace and timeout

[jcastillo at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16493

            Bug ID: 16493
           Summary: Improve bkl.stp to add backtrace and timeout
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: testsuite
          Assignee: systemtap at sourceware dot org
          Reporter: jcastillo at redhat dot com

Created attachment 7366
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7366&action=edit
Proposed patch

Hello, 

Most of the times, when we use bkl.stp to investigate BKL issues, we've found
useful to have the backtrace of the function that holds the BKL.
The patch attached adds a new command line option, "backtrace=N", that when
used enables the use of print_backtrace(). The value of <N>, if present, is
taken as useconds, and it is the limit of time the task or tasks have been
waiting to acquire the lock i.e.:

  # stap blk.stp backtrace=100

That would enable printing of backtrace on all tasks holding the kernel
big lock for more than 100us.

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[Bug testsuite/16493] Improve bkl.stp to add backtrace

[jcastillo at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16493

Jose Castillo <jcastillo at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Improve bkl.stp to add      |Improve bkl.stp to add
                   |backtrace and timeout       |backtrace

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[Bug testsuite/16493] Improve bkl.stp to add backtrace

[dsmith at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16493

David Smith <dsmith at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dsmith at redhat dot com

--- Comment #1 from David Smith <dsmith at redhat dot com> ---
Sorry for taking so long to look at this. I like the idea of your patch, but we
can simplify it a bit.

We can remove all the command line processing, and just use stap command line
processing with the ability to set global variables from the command line using
'-G'. Here's an example of how it works:

====
# stap -e 'global backtrace=-1; probe begin { printf("%d\n", backtrace); exit()
}' -G backtrace=100
100
====

Thanks again for the patch.

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[Bug testsuite/16493] Improve bkl.stp to add backtrace

[flu at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16493

Felix Lu <flu at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |flu at redhat dot com
         Resolution|---                         |FIXED

--- Comment #2 from Felix Lu <flu at redhat dot com> ---
Merged and removed command line processing in favour for -G

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