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

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

[dsmith at redhat dot com]

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: systemtap@sourceware.org
        ReportedBy: dsmith@redhat.com
    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

[dsmith at redhat dot com]

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

[fche at redhat dot com]

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

[fche at redhat dot com]

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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