[Bug translator/14689] New: missing 'syscalls' tracepoints

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[Bug translator/14689] New: missing 'syscalls' tracepoints

albert.aribaud at 3adev dot fr


http://sourceware.org/bugzilla/show_bug.cgi?id=14689



             Bug #: 14689

           Summary: missing 'syscalls' tracepoints

           Product: systemtap

           Version: unspecified

            Status: NEW

          Severity: normal

          Priority: P2

         Component: translator

        AssignedTo: [hidden email]

        ReportedBy: [hidden email]

    Classification: Unclassified





Systemtap can only find less than half of the tracepoints perf knows about:



----

# perf list tracepoint | wc -l

924

# stap -l 'kernel.trace("*")' | wc -l

409

----



The majority of these missing tracepoints are the 'syscalls' family of

tracepoints:



----

# perf list tracepoint | grep ' syscalls:' | wc -l

556

# perf list tracepoint | grep ' syscalls:' | head

  syscalls:sys_enter_socket                          [Tracepoint event]

  syscalls:sys_exit_socket                           [Tracepoint event]

  syscalls:sys_enter_socketpair                      [Tracepoint event]

  syscalls:sys_exit_socketpair                       [Tracepoint event]

  syscalls:sys_enter_bind                            [Tracepoint event]

  syscalls:sys_exit_bind                             [Tracepoint event]

  syscalls:sys_enter_listen                          [Tracepoint event]

  syscalls:sys_exit_listen                           [Tracepoint event]

  syscalls:sys_enter_accept4                         [Tracepoint event]

  syscalls:sys_exit_accept4                          [Tracepoint event]

----



Systemtap can't find those tracepoints:



----

# stap -l 'kernel.trace("sys_enter_")'

# stap -l 'kernel.trace("sys_exit_")'

----



These tracepoints only exist if CONFIG_FTRACE_SYSCALLS is enabled. If

CONFIG_FTRACE_SYSCALLS is enabled, some macro magic automatically creates these

tracepoints in the SYSCALL_DEFINEn macros.



(Note that this problem might be related to bug #10745)



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[Bug translator/14689] missing 'syscalls' tracepoints

albert.aribaud at 3adev dot fr


http://sourceware.org/bugzilla/show_bug.cgi?id=14689



David Smith <dsmith at redhat dot com> changed:



           What    |Removed                     |Added

----------------------------------------------------------------------------

             Blocks|                            |14690



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[Bug translator/14689] missing 'syscalls' tracepoints

albert.aribaud at 3adev dot fr
In reply to this post by albert.aribaud at 3adev dot fr


http://sourceware.org/bugzilla/show_bug.cgi?id=14689



--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> 2012-10-09 19:44:50 UTC ---

Note that stap does give access to the master tracepoints sys_enter and

sys_exit.  At one point, the demultiplexing done by the kernel for perf/ftrace

was such that there weren't really N low-level tracepoints that may be

individually turned on/off.  If any was turned on, the process incurred a

penalty for *every* syscall.  Demultiplexing was just a conditional

postprocessing phase, by which time the damage was already done.  It roughly

equivalent to



probe kernel.trace.sys_five = kernel.trace("sys_enter")

      { if ($syscall != 5) next; }



If this is still the case, then there is little point trying to connect to the

same demultiplexing widget.



See also bug #12748.



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[Bug translator/14689] missing 'syscalls' tracepoints

albert.aribaud at 3adev dot fr
In reply to this post by albert.aribaud at 3adev dot fr
https://sourceware.org/bugzilla/show_bug.cgi?id=14689

Frank Ch. Eigler <fche at redhat dot com> changed:

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

--- Comment #2 from Frank Ch. Eigler <fche at redhat dot com> ---
tp_syscalls.* present

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